Oil Paint

It has been more than eight  hundred  years since the introduction  of oil into the technology of painting, and there have been four major factors that have contributed to the development of oil paint and oil painting as they are known today. The first was in 1390 when it was discovered that zinc and lead pigments added to the oil paint sped drying time. This made oil painting feasible in damp or humid cli­ mates, such as in Italy and the Netherlands, where oil painting as a viable medium was first introduced.

In the sixteenth century, such natural resins as damar and mastic were introduced to the oil, allowing for the later development of the thicker alla prima style of painting. This oil-resin paint produced a paint film of great durability and was preferred by many of the Old Masters for use in glazing with successive layers of paint, but most of their specific recipes for making resin-oils and information regarding drying times are now lost. Many artists have since tried to duplicate the technology wherein glazes interlock to give that unsurpassed beauty and clarity so evident in the Masters' work, but, alas, have failed.

The period of industrialization during the nineteenth century  brought  with  it not only a great new spectrum of pigments for artistic use, but also the collapsi­ ble tin tube, without which the Impressionist and Luminist painting movements could not have happened. 

Pigments such as cobalt blue, chromium  oxide  green,  cadmium  yellow, chrome yellow, barium yellow, zinc yellow, cerulean blue, ultramarine blue (synthetic), zinc white, viridian, and cobalt violet were all introduced to oil  painting for the first time in the nineteenth century. Such brilliant blues, yellows, and greens had not, and could  not have,  been seen  in painting  until  this time,  but it was the invention of the collapsible tin  tube in 1841 that  made it practical for the artist to leave the confines of the studio to paint outdoors. Before the development of the tin tube, colors had to be ground fresh or, where available, bought fresh in either perishable animal-skin bladders  or expensive  metal syringes from colormen, as the first manufacturers of artists' paints were called. The development of prepackaged oil paints was a great advance, though not without some sacrifices in quality, which  might seem  minor  by comparison  to the convenience but are nevertheless significant and noteworthy. Resin-oil paints were far more brilliant than resin-free oil paints, and each color could be formu­ lated to dry at a similar rate to allow for proper interlocking of paint films. But, because of packaging and shelf life, resin-oil paint had to give way to resin-free oil paint. Resin-free oil paints have a high oil content with irregular drying times

and poorer aging characteristics.

Attempts are still being made to deal with the problems of handling char­ acteristics, packaging, and shelf  life.  Some  manufacturers  are  experimenting with different methods of grinding and aging  paint and  are trying  new  drying  oils or synthetic resins like alkyds, or are even attempting to reconstruct the old resin-oil paint with modern technology.

Oil paint, despite even the advent of acrylic, is still the most versatile, rich­ looking, and time-tested painting medium of all time.

The Manufacture of Oil Paints

 With the Excepton, of a few  pigments  that  are too delicate  to be  made other  than by hand, oil paints are generally made by machine. The  machine  process is far more effective than the techniques used in making paints by hand,  and the range of available colors is much greater.

 

MACHINE-MADE PAINTS

Most commercial artist-grade oil paints are made with some variation, or abbre­ viation, of the following description supplied by the Holbein Company.

The first stage is the preparation of a mill-base, a mixture of pigment, oil, and resins  in   ratios   prescribed   by   the   natural   characteristics   of   each   pigment,   which is then placed in an agitator to disperse the ingredients evenly. Some pigments require a vacuum agitator to remove water and gas. If the mill-base is not prop­erly prepared, the next stage of grinding will not be effective.

Additional medium and pigment are mixed with the mill-base and fed into the first series of rollers to grind the mixture and produce a  base-paint.  The purpose of grinding is to coat each particle of pigment completely with the medium, or vehicle. This isolates and protects the pigment from reacting chemically  with other uncoated pigments, and is what gives oil paint its brilliant quality. That quality is determined during this stage of processing. The rollers that grind the paint are made from iron, stone, and ceramic, and are used individually or in combination with varying ratios of revolutions depending on the nature of the pigment (most pigments at this stage are ground three or four times starting with the iron, then the stone, and finally the ceramic rollers to make an artist-grade paint). If there is too much grinding, the pigment will be pulverized and its brilliance lost, and if there is too little grinding, the paint will be oily and gritty. The third stage is the adjustment process  where  the  base-paint  is mixed with   an antiseptic, an antifungal agent, driers (if  needed),  and  stabilizers  (such  as wax, if needed),  and  is  ground  two  to three  times more. At this time, the color is also adjusted to match a previous company standard. The finished product is then tested for tinting strength,  covering  power,  handling properties, resistance to putrefaction, and stability under exposure to light and variations in tempera­ ture. After quality control standards have been met, the mixture is aged. This

allows any excess oil to separate naturally from the pigment so that it can be removed before the final process of filling the tubes.

The manufacturing process described here is for an extra-fine quality, or artist­ grade paint. Lesser grades are manufactured with substantially less grinding and quality control, as well as less expensive ingredients.

 

HANDMADE PAINTS

With the exception of a few delicate pigments such as genuine carmine, madder, and lapis lazuli (genuine ultramarine), the unromantic truth is that handmade oil paint is rarely as good as the best machine-made paint. The main reason is that machine grinding, or ball grinding, coats the individual particles  more  thor­ oughly with far less oil (less oil means a lower risk of  yellowing  and cracking) than could possibly be done by hand. Other drawbacks  to  hand  grinding  your own paint are storage problems, spoilage, and considerable health hazards, also assuming you know the proper ratios of vehicle to pigment and how to combine them and that you possess the proper tools.  As  for  saving  money  by  making your own paint, most people who have tried it have found that, for the average painter, it is not worth it.

The only reasons for an artist to make his or her own paint, in spite of all the obstacles, is either for the learning experience or to make a paint that cannot be bought, such as a resin-oil paint or restoration  paint; however,  even  these types  of paint are becoming commercially available in the United States. Blockx paint is the last commercially available, extra-fine, handmade paint. Because it is handmade, it is not only very expensive, but the range of colors is small by comparision to other lines of extra-fine paints and the supply of those colors is extremely limited.

 

Characteristics of Oil Paint

THE MOST IMPORTANT and  unique characteristic of oil paint is the thin coating of  oil on each particle of pigment. This coating usually  consists  of  a "drying" oil such as linseed or poppy oil. The oil dries  through  oxidation,  a chemical  reac­ tion between the oxygen in the air and the oil, and not through evaporation. This oxidation process creates a remarkably durable and flexible  paint  film.  Since  each particle is separated by a clear film, light can pass between some of the particles of pigment, as well reflect off others. It is these characteristics that give this painting medium its great depth and luminosity, when used correctly.

The two most common errors in oil painting are caused by varnishing  a paint­ ing before complete oxidation has occurred (a painting may appear dry  to  the touch in several weeks, but it is often a year before the  process  is  complete enough for a final varnish), and by using too much thinner, which strips off the protective oil coating, often resulting in unpredictable, and sometimes even disastrous effects. Painters will often buy the finest oil paints and then saturate them, using no medium, with the cheapest paint thinner, only to complain about how bad the paint looks and handles.

Without a thorough understanding of the role of drying oils, solvents,  var­ nishes, and pigments, no painter is equipped to take advantage of what oil paints can do.

 

DURABILITY

Over a long period of time, oil paintings will  tend  to  darken,  yellow,  and develop fine cracks in the surface. Yet the overall beauty and richness has sur­ vived centuries, a testament to the durability of oil painting.

 

PURITY AND LABELING

The term "pure" has been as overemployed in reference to paint as it has in reference to food. It is difficult to derive any  practical  information  from  the use of the term. For example, in the making of the finest artist-grade oil paint, only C.P., or chemically pure, cadmium  sulfo-selenide (PR 108, C.I.  77196)  is used  to make a cadmium red color. Yet roughly half the contents of the paint tube consists of oil, with a small percentage of wax stabilizers, and usually a touch of drier. Consequently, it is difficult to understand what  the  resulting  chemical purity is or means after a pigment has been blended  with stabilizers  and  driers, and in lesser grades of paint, fillers are added, too.

There have been attempts in the recent past to establish some form of stand­ardization in the United States. These efforts have resulted in Commercial Stand­ ard CS98-62, published by the United States Department of Commerce  (a copy can be had by writing to the Superintendent of Documents, Washington D.C., 20025). It is a voluntary standard allowing those who conform to it  to say so in their labeling. The standard seems to have been  written  with  a  manufacturer's bias, rather than a consumer's bias, as well as a bias toward middle quality, and would seem to eliminate those manufacturers who produce the worst  paint and those manufacturers that produce some of the best paint (primarily in the area of resin-oil) from using the approved label. Few manufacturers ever  fully  comply with this standard.

Another important outgrowth of the standardization efforts is the use of color indexing for artists' paints. Color indexing is a fairly specific method of identify­ ing a pigment and establishing purity. (For information about this seven-volume index, write to the American Association of Textile Chemists and Colorists,

P. O. Box 12215, Research Triangle Park, NC 27709. A reference copy can often  be found in a university chemistry library or a public library that has a science reference section.) This information is particularly important to restorers, deco­ rators, and paint manufacturers. The indexing numbers can be helpful to artists when these numbers are accompanied by the traditional names and  chemical names for the pigments and, in cases where more than one pigment is used, their ratios. At this time, no manufacturer is supplying  such  ratios  when  more  than one pigment is used. Some have even eliminated the traditional name in favor of only the index number, which is most discouraging because it makes valuable information inaccessible to all but the most scientific of painters.

A set of voluntary standards is now being established by the American Society for Testing and Materials (ASTM). This will be an improvement on the Commer­ cial Standard CS98-62, as well as on labeling. Voluntary standards concerning health hazards and the labeling of hazardous materials are set down in ASTM D 4236, Standard Practice for Art  Materials  for Chronic  Health  Hazards.  ASTM D 4302, Standard Specifications for Artists' Oil and Acrylic  Emulsion  Paints, deals with improved labeling, while ASTM D 4303, Test Methods for Relative Lightfastness of Pigments Used in Artists' Paints, attempts to standardize light­ fastness test procedures. A copy of each of these documents is available, for $8.00 each, from ASTM Sales  Services  Dept.,  1916  Race Street,  Philadelphia, PA 19103. Manufacturers that conform to these  standards  will  be  permitted  to say that their product "Conforms to ASTM D 4302." The ASTM recommends guidelines for proper testing and labeling, but does no testing. The supplying of accurate and meaningful labeling,  as  well  as supplemental  product  information, is still almost entirely up to the good will of the manufacturers of artists'  mate­ rials. Compliance with these guidelines should be higher than it has been with Commercial Standard CS98-62.

Winsor & Newton makes a point of advertising the compliance of its London Oil Colour and London Alkyd Colour with  these  new  standards.  (These  two  lines of Winsor & Newton paint are, however,  its lesser grade; it has,  curiously, not involved its artist-grade oils.) It boldly labels its compliance on these paint tubes. But this information is no more meaningful to the average consumer of artists' materials than was the Commercial Standard CS98-62. The company has added such information as the chemical name of the  pigment  used,  a  perma­ nency rating, a lightfastness rating, and the vehicle used. At  first  glance  this  would appear to be a vast improvement, yet most of this information has been commonly supplied on paint labels by most manufacturers for several years. The remaining information, as with virtually all current labeling, is in a form that, recurrently, is not truly meaningful.

Complete labeling, backed up with easily accessible, in-depth technical infor­ mation, is needed. The labeling on artists' paints should  be at least  as good  as  what we have now come to expect on the food we buy. This is easier said than done, especially in an industry with such a variety of products. It is obvious that new labeling is continually developing, and it would  be a great  service  to the artist if labels supplied meaningful information. The subject of purity and stand­ ards is already controversial, but it is nevertheless necessary  to  point  out  how little practical information, especailly in regard to purity, is accessible to the average painter, who is often left with little alternative but  to accept  the reputa tion of the manufacturer. 

 

PERMANENCE

Permanence, in regard to the lightfastness and compatibility of the pigments, is discussed extensively in the chapter on pigments,  pages 154  to 156.  It is impor­ tant to understand, however, that the general permanence of colors in oil paint is dependent on the protective coating that each particle of pigment possesses. Although the protective coating allows the use of many pigments that might otherwise interact chemically if combined in their dry unprotected form, it also reduces the permanency of the color that is produced by the pigment. As the protective coating ages, it tends to darken and yellow,  particularly  if that coating is comprised primarily of linseed oil, which changes the color.

The permanence of oil paint is also affected by atmospheric pollution, such as the sulfur dioxide and hydrogen sulfide present in city air. Unprotected (unvar­ nished) metal-based paints like the chrome colors, such as chrome yellow, and chrome green, white lead, cremnitz white, cinnabar green, as well as colors like ultramarine blue and permanent blue, can discolor  when  they  come in  contact with these pollutants.

Such colors as alizarin crimson, brown madder alizarin, indigo,  permanent green, and purple madder alizarin are not as  permanent  when  used  in  thin glazes. Scarlet lake (BON arylamide) and Winsor orange (BON arylamide and arylamide yellow) oil colors by Winsor & Newton  are particularly  sensitive  to pale tints with white. Mixing white, or any color of greater pem1anency,  with colors of lesser permanency does not improve the permanency of the latter and often reduces it.

TINTING STRENGTH

The ability of an oil color to maintain its strength when mixed with  white  is  known as tinting  strength.  This is a common  test  for pigment  concentration  and a valid method of comparison between brands of paint if the  pigment  used  by each is the same. The name of the color on  the tube does  not  necessarily  indi­ cate what is in the tube. For example, a well-advertised tinting test shows two different brands of raw sienna. The advertiser's brand show greater strength of color. However, the pigments tested are similar, but not the same. The weaker­ appearing brand of raw sienna is said to contain iron oxide mined from the traditional sites in Italy, which is high in silica and produces a more transparent color. The advertiser's brand is said to be a manufactured iron oxide,  which contains no silica and thereby produces a stronger tinting  strength.  The  point is not which is the more desirable characteristic and thereby which  is  the  better paint, but rather that this is not a fair comparison.

Tinting tests can be made fair and can be performed by anyone once two identical pigments from two different brands have been identified. Within two brands of paint, about 25 percent will cross match using the same single pigment for a particular color. It is important to avoid testing colors that contain several pigments, even if they are identical, because the proportions for each pigment may be different. You can make a test mixing half zinc white with half color, and then take half of that mixture and mix it with half zinc white again, and repeat this procedure several times for each brand. This will give you a serial dilution, which can then be compared.

Small differences between brands in tinting strength  are best ignored  because the most concentrated use of a pigment to make a color is not always desirable. Some pigments become literally unworkable above certain concentrations. Paints made with too high a concentration of metal pigments such as cadmium or lead become so thick and cakey that they cannot be easily expelled from the tube or manipulated on the palette. Paints made with some of the newer synthetic pig­ ments, such as phthalocyanine, have such high tinting strength that if they were used in high concentrations, they would totally overpower any color mixed with them. Because of these factors, manufacturers balance the level of concentration with the working consistency. Any home-done tint test comparison needs to be judged against your preferences for the particular paint consistency that a manu­ facturer offers.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The Manufacture of Oil Paints

Wth the excepton of a few pigmentsthat  are too delicate  to be  made other  than by hand, oil paints are generally made by machine. The  machine  process is far more effective than the  techniques used in making paints by hand,  and the range of available colors is much greater.

 

MACHINE-MADE PAINTS

Most commercial artist-grade oil paints are made with some variation, or abbre­ viation, of the following description supplied by the Holbein Company.

The first stage is the preparation of a mill-base, a mixture of pigment, oil, and resins  in   ratios   prescribed   by   the   natural   characteristics   of   each   pigment,   which is then placed in an agitator to disperse the ingredients evenly. Some pigments require a vacuum agitator to remove water and gas. If the mill-base is not prop­ erly prepared, the next stage of grinding will not be effective.

Additional medium and pigment are mixed with the mill-base and fed into the first series of rollers to grind the mixture and produce a  base-paint.  The purpose of grinding is to coat each particle of pigment completely with the medium, or vehicle. This isolates and protects the pigment from reacting chemically  with other uncoated pigments, and is what gives oil paint its brilliant quality. That quality is determined during this stage of processing. The rollers that grind the paint are made from iron, stone, and ceramic, and are used individually or in combination with varying ratios of revolutions depending on the nature of the pigment (most pigments at this stage are ground three or four times starting with the iron, then the stone, and finally the ceramic rollers to make an artist-grade paint). If there is too much grinding, the pigment will be pulverized and its brilliance lost, and if there is too little grinding, the paint will be oily and gritty. The third stage is the adjustment process  where  the  base-paint  is mixed with   an antiseptic, an antifungal agent, driers (if  needed),  and  stabilizers  (such  as wax, if needed),  and  is  ground  two  to three  times more. At this time, the color is also adjusted to match a previous company standard. The finished product is then tested for tinting strength,  covering  power,  handling properties, resistance to putrefaction, and stability under exposure to light and variations in tempera­ ture. After quality control standards have been met, the mixture is aged. This allows any excess oil to separate naturally from the pigment so that it can be removed before the final process of filling the tubes.

The manufacturing process described here is for an extra-fine quality, or artist­ grade paint. Lesser grades are manufactured with substantially less grinding and quality control, as well as less expensive ingredients.

 

HANDMADE PAINTS

With the exception of a few delicate pigments such as genuine carmine, madder, and lapis lazuli (genuine ultramarine), the unromantic truth is that handmade oil paint is rarely as good as the best machine-made paint. The main reason is that machine grinding, or ball grinding, coats the individual particles  more  thor­ oughly with far less oil (less oil means a lower risk of  yellowing  and cracking) than could possibly be done by hand. Other drawbacks  to  hand  grinding  your own paint are storage problems, spoilage, and considerable health hazards, also assuming you know the proper ratios of vehicle to pigment and how to combine them and that you possess the proper tools.  As for saving  money  by  making your own paint, most people who have tried it have found that, for the average painter, it is not worth it.

The only reasons for an artist to make his or her own paint, in spite of all the obstacles, is either for the learning experience or to make a paint that cannot be bought, such as a resin-oil paint or restoration  paint; however,  even  these types  of paint are becoming commercially available in the United States. Blockx paint is the last commercially available, extra-fine, handmade paint. Because it is handmade, it is not only very expensive, but the range of colors is small by comparision to other lines of extra-fine paints and the supply of those colors is extremely limited.

Characteristics of Oil Paint

The most Important and  unique characteristic of oil paint is the thin coating of  oil on each particle of pigment. This coating usually  consists  of  a "drying" oil such as linseed or poppy oil. The oil dries  through  oxidation,  a chemical  reac­ tion between the oxygen in the air and the oil, and not through evaporation. This oxidation process creates a remarkably durable and flexible  paint  film.  Since  each particle is separated by a clear film, light can pass between some of the particles of pigment, as well reflect off others. It is these characteristics that give this painting medium its great depth and luminosity, when used correctly.

The two most common errors in oil painting are caused by varnishing  a paint­ ing before complete oxidation has occurred (a painting may appear dry  to  the touch in several weeks, but it is often a year before the  process  is  complete enough for a final varnish), and by using too much thinner, which strips off the protective oil coating, often resulting in unpredictable, and sometimes even disastrous effects. Painters will often buy the finest oil paints and then saturate them, using no medium, with the cheapest paint thinner, only to complain about how bad the paint looks and handles.

Without a thorough understanding of the role of drying oils, solvents,  var­ nishes, and pigments, no painter is equipped to take advantage of what oil paints can do.

 

DURABILITY

Over a long period of time, oil paintings will  tend  to  darken,  yellow,  and develop fine cracks in the surface. Yet the overall beauty and richness has sur­ vived centuries, a testament to the durability of oil painting.

 

PURITY AND LABELING

The term "pure" has been as overemployed in reference to paint as it has in reference to food. It is difficult to derive any  practical  information  from  the use of the term. For example, in the making of the finest artist-grade oil paint, only C.P., or chemically pure, cadmium  sulfo-selenide (PR 108, C.I.  77196)  is used  to make a cadmium red color. Yet roughly half the contents of the paint tube consists of oil, with a small percentage of wax stabilizers, and usually a touch of drier. Consequently, it is difficult to understand what  the  resulting  chemical purity is or means after a pigment has been blended  with stabilizers  and  driers, and in lesser grades of paint, fillers are added, too.

There have been attempts in the recent past to establish some form of stand­ ardization in the United States. These efforts have resulted in Commercial Stand­ard CS98-62, published by the United States Department of Commerce  (a copy can be had by writing to the Superintendent of Documents, Washington D.C., 20025). It is a voluntary standard allowing those who conform to it  to say so in their labeling. The standard seems to have been  written  with  a  manufacturer's bias, rather than a consumer's bias, as well as a bias toward middle quality, and would seem to eliminate those manufacturers who produce the worst  paint and those manufacturers that produce some of the best paint (primarily in the area of resin-oil) from using the approved label. Few manufacturers ever  fully  comply with this standard.

Another important outgrowth of the standardization efforts is the use of color indexing for artists' paints. Color indexing is a fairly specific method of identify­ ing a pigment and establishing purity. (For information about this seven-volume index, write to the American Association of Textile Chemists and Colorists, P. O. Box 12215, Research Triangle Park, NC 27709. A reference copy can often  be found in a university chemistry library or a public library that has a science reference section.) This information is particularly important to restorers, deco­ rators, and paint manufacturers. The indexing numbers can be helpful to artists when these numbers are accompanied by the traditional names and  chemical names for the pigments and, in cases where more than one pigment is used, their ratios. At this time, no manufacturer is supplying  such  ratios  when  more  than one pigment is used. Some have even eliminated the traditional name in favor of only the index number, which is most discouraging because it makes valuable information inaccessible to all but the most scientific of painters.

A set of voluntary standards is now being established by the American Society for Testing and Materials (ASTM). This will be an improvement on the Commer­ cial Standard CS98-62, as well as on labeling. Voluntary standards concerning health hazards and the labeling of hazardous materials are set down in ASTM D 4236, Standard Practice for Art  Materials  for Chronic  Health  Hazards.  ASTM D 4302, Standard Specifications for Artists' Oil and Acrylic  Emulsion  Paints, deals with improved labeling, while ASTM D 4303, Test Methods for Relative Lightfastness of Pigments Used in Artists' Paints, attempts to standardize light­ fastness test procedures. A copy of each of these documents is available, for $8.00 each, from ASTM Sales  Services  Dept.,  1916  Race Street,  Philadelphia, PA 19103. Manufacturers that conform to these  standards  will  be  permitted  to say that their product "Conforms to ASTM D 4302." The ASTM recommends guidelines for proper testing and labeling, but does no testing. The supplying of accurate and meaningful labeling,  as  well  as supplemental  product  information, is still almost entirely up to the good will of the manufacturers of artists'  mate­rials. Compliance with these guidelines should be higher than it has been with Commercial Standard CS98-62.

Winsor & Newton makes a point of advertising the compliance of its London Oil Colour and London Alkyd Colour with  these  new  standards.  (These  two  lines of Winsor & Newton paint are, however,  its lesser grade; it has,  curiously, not involved its artist-grade oils.) It boldly labels its compliance on these paint tubes. But this information is no more meaningful to the average consumer of artists' materials than was the Commercial Standard CS98-62. The company has added such information as the chemical name of the  pigment  used,  a  perma­ nency rating, a lightfastness rating, and the vehicle used. At  first  glance  this  would appear to be a vast improvement, yet most of this information has been commonly supplied on paint labels by most manufacturers for several years. The remaining information, as with virtually all current labeling, is in a form that, recurrently, is not truly meaningful.

Complete labeling, backed up with easily accessible, in-depth technical infor­ mation, is needed. The labeling on artists' paints should  be at least  as good  as  what we have now come to expect on the food we buy. This is easier said than done, especially in an industry with such a variety of products. It is obvious that new labeling is continually developing, and it would  be a great  service  to the artist if labels supplied meaningful information. The subject of purity and stand­ ards is already controversial, but it is nevertheless necessary  to  point  out  how little practical information, especailly in regard to purity, is accessible to the average painter, who is often left with little alternative but  to accept  the reputa­ tion of the manufacturer.

 

PERMANENCE

Permanence, in regard to the lightfastness and compatibility of the pigments, is discussed extensively in the chapter on pigments,  pages 154  to 156.  It is impor­ tant to understand, however, that the general permanence of colors in oil paint is dependent on the protective coating that each particle of pigment possesses. Although the protective coating allows the use of many pigments that might otherwise interact chemically if combined in their dry unprotected form, it also reduces the permanency of the color that is produced by the pigment. As the protective coating ages, it tends to darken and yellow,  particularly  if that coating is comprised primarily of linseed oil, which changes the color.

The permanence of oil paint is also affected by atmospheric pollution, such as the sulfur dioxide and hydrogen sulfide present in city air. Unprotected (unvarnished) metal-based paints like the chrome colors, such as chrome yellow, and chrome green, white lead, cremnitz white, cinnabar green, as well as colors like ultramarine blue and permanent blue, can discolor when they come in contact with these pollutants.

Such colors as alizarin crimson, brown madder alizarin, indigo,  permanent green, and purple madder alizarin are not as  permanent  when  used  in  thin glazes. Scarlet lake (BON arylamide) and Winsor orange (BON arylamide and arylamide yellow) oil colors by Winsor & Newton  are particularly  sensitive  to pale tints with white. Mixing white, or any color of greater pem1anency,  with colors of lesser permanency does not improve the permanency of the latter and often reduces it.

TINTING STRENGTH

The ability of an oil color to maintain its strength when mixed with  white  is  known as tinting  strength.  This is a common  test  for pigment  concentration  and a valid method of comparison between brands of paint if the  pigment  used  by each is the same. The name of the color on  the tube does  not  necessarily  indi­ cate what is in the tube. For example, a well-advertised tinting test shows two different brands of raw sienna. The advertiser's brand show greater strength of color. However, the pigments tested are similar, but not the same. The weaker­ appearing brand of raw sienna is said to contain iron oxide mined from the traditional sites in Italy, which is high in silica and produces a more transparent color. The advertiser's brand is said to be a manufactured iron oxide,  which contains no silica and thereby produces a stronger tinting  strength.  The  point is not which is the more desirable characteristic and thereby which  is  the  better paint, but rather that this is not a fair comparison.

Tinting tests can be made fair and can be performed by anyone once two identical pigments from two different brands have been identified. Within two brands of paint, about 25 percent will cross match using the same single pigment for a particular color. It is important to avoid testing colors that contain several pigments, even if they are identical, because the proportions for each pigment may be different. You can make a test mixing half zinc white with half color, and then take half of that mixture and mix it with half zinc white again, and repeat this procedure several times for each brand. This will give you a serial dilution, which can then be compared.

Small differences between brands in tinting strength  are best ignored  because the most concentrated use of a pigment to make a color is not always desirable. Some pigments become literally unworkable above certain concentrations. Paints made with too high a concentration of metal pigments such as cadmium or lead become so thick and cakey that they cannot be easily expelled from the tube or manipulated on the palette. Paints made with some of the newer synthetic pig­ ments, such as phthalocyanine, have such high tinting strength that if they were used in high concentrations, they would totally overpower any color mixed with them. Because of these factors, manufacturers balance the level of concentration with the working consistency. Any home-done tint test comparison needs to be judged against your preferences for the particular paint consistency that a manu­ facturer offers.

TRANSPARENCY OR OPACITY

In oil paint each pigment, by its own chemical nature, will tend to be either transparent, semitransparent, or opaque. Most blacks, blues, violets, and  purples are transparent, as are colors where the pigment is a like a dye-pigment, such as alizarin crimson and madder. Earth colors range from semitransparent to opaque, depending on their source. All cudmium und chrome colors, all whites, or colors that are made with white (such as Naples yellow and flesh tint), and genuine vermilion are opaque.

Of all the whites, zinc white is most transparent, followed  by lead  white and then titanium white, the most opaque. You can make a transparent color semi­ transparent or opaque by the addition of white. Many colors will take up to 10 percent white without any appreciable change in the surface appearance. Opaque colors can often be made semitransparent by thinning them with  a  painting medium and applying in thin glazes.

Virtually all manufacturers' color charts are encoded with information  regard­ ing the transparency and opacity of the colors in their unmixed state. Some companies, such as Schmincke, even label their paint tubes.  It  is  important  to note that in lesser grades of paint, it is more common to have expensive colors replaced with blends of other less costly colors, which in turn can affect the transparency and opacity. A mixture of white and phthalocyanine blue,  for example, is sometimes sold as cobalt blue, or cobalt blue hue.  This  blend  is opaque and does not produce the same kinds of tints when mixed  with  other colors. Genuine cobalt blue is prized for  its  transparency  as  well  the  delicate tints it can produce. Another example is  cadmium  red,  the  better  grades  of which are made from C.P. cadmium sulfo-selenide, and which is prized for its opacity and brilliance. It is sometimes replaced with  lesser  grades,  which  are often mixed with barium sulfate, and are therefore less opaque and  not as bril­ liant.

It  used  to  be  common  practice  simply  to  paint  over  undesirable  areas  with opaque colors until it was discovered, after  many  years  of  aging, that  areas which were hidden began to show through the increasingly transparent surface. This phenomenon is called pentimento. Therefore, if an  area  needs to  be repainted, the area should first  be  prepared  with a  new  ground  of white paint. To an artist who paints very large,  these  differences  may seem insignificant for, if one has to stand twenty to thirty feet back from  the surface  of the painting to see it, it is unlikely that small details will be noticed. However, if you are a master  at the craft of  painting,  or paint in a style where details  must  and  will  be seen, these differences are very important.

BINDERS

The nature of oil paint is such that particles of pigment are coated  and suspended in a liquid, which, in turn, will bind  those  particles  together  when  exposed  to air. That liquid may be a drying oil, a resin-oil blend, or an oil-modified alkyd resin.

Drying Oils. These oils are used in grinding pigment  to form  an oil  paint,  as  well as to make media for oil painting. It is the  linolenic  and  linoleic  acids present in a drying oil (commonly linseed oil) that, when in contact with air, oxidize to form a film that binds the particles of pigments together.

Some manufacturers substitute a refined poppy  oil or safflower  oil for linseed oil in preparing  certain  pale oil colors and  whites.  These drying  oils have little  or no linolenic acid, a binder that gives a yellow  tint  to  oil  paint.  The  only binder in these oils is the linoleic acid, which is not only less yellow, but also yellows less over time. However, linoleic acid by itself is a weaker binder and should not be used as a replacement for linseed oil in all cases.

Using a "pure oil" system of making paint is the least  costly  method  and, unless driers and wax stabilizers are added to certain colors, there will be wide variations in consistency and drying times between many  colors.  This  type of paint is referred to as "fat" paint because of the high oil content. The fatter the paint, the more yellowing and the greater the  possibility  for future  cracking. Some manufacturers have attempted to reduce the "fat" either by an elaborate grinding system, such as that used by the Holbein Company, or by aging the

paint  before  packaging,  a method  employed  by Grumbacher

.

Resin-Oil. The Schmincke Company has developed the use of a resin-oil binder, which is stable in tube paints and similar to that  used  by  the  Old  Masters.  Its line of oil paint has been named Mussini in honor of Cesare Mussini, a nine­ teenth-century painter and teacher who was one of the few remaining repositories of some of the Old Masters' paint-making recipes, and who passed this knowl­  edge on to the colormen of Schmincke. Mussini oil paint is  made  with  such drying oils as cold-pressed and refined linseed oils, poppy oil, and sunflower oil, which are blended with natural resins like damar and mastic, as well as with polycyclohexanone, a modem nonyellowing damarlike resin.

This elaborate formulation allows for four important effects:  more even drying of paint films, which reduces the possibilities of future cracking;  greater clarity  and less yellowing because of the lower oil content; narrowing the  range  of  drying times between different pigments; and smooth and even consistency with little or no separation of oil and pigments.

The mixing of such ingredients as mastic and damar  into a paint after it has  been ground with only linseed oil, will help to improve the paint's performance. However, it is not the same as when the pigment is ground into the same com­ bination of ingredients to start with, where less oil and more resin can be used. When the ingredients are added  later to a high-oil-content paint,  the  original  oil in the tube is only diluted,  not replaced,  and the increase in  performance  is not  as dramatic.

Oil-Modified Alkyd Resin. Alkyd resin is the category of resins that are made from mixtures of dibasic acids and polyhydric alcohols.  One  particular  alkyd resin (kept a trade secret) is chemically  combined  with a nonyellowing  oil, such as safflower oil, to produce a workable, fast-drying  binder for oil paints.  Driers  are often included to speed drying and silica is occasionally added to give extra body.

Alkyd resins often exhibit a thixotropic effect. Thixotropy is an unusual phe­ nomenon in which a gel, or paste, suddenly loses its plasticity when disturbed or moved mechanically, resulting in a liquid. The opposite may also occur where a liquid, left undisturbed, forms into a gel. There is a certain advantage to this thixotropic property in the glazing technique, for a  glaze  will  resist  running  down the canvas after it has been applied and left undisturbed. However, the tendency of alkyds to liquify rapidly would be a disadvantage in the impasto technique.

 

 

Alkyd resins, originally developed for use in making industrial paints,  have  been applied to make a variety of fast-drying media for artists' paints. Winsor & Newton has produced two lines of paint (an artist-grade and an amateur-grade) where the pigments have been ground into an oil-modified alkyd  resin.  The  range of colors is limited to its "selected list" (SL), which consists of colors that may be mixed with one another without loss of permanence. At this time it is not clear if pigments other than those currently  used in nonalkyd paint are safe to be stored in tubes after being ground into this acidic resin. It does seem to be all right, however, to intermix nonalkyd paint with alkyd paint, and nonalkyd medium with alkyd medium for immediate use.

Alkyd paints and alkyd media should not be overthinned. No more than 25 percent by volume of thinner to paint  or  medium  is recommended;  more  than this will break down the consistency and quality of the paint or medium.

 

DRYING RATES

Each pigment affects the  drying  rate  of  its oil  vehicle differently.  Some speed the oxidation process, some slow it down, and some have no effect at all. To compensate for this, most manufacturers add a small amount of drier, such  as cobalt or manganese, to the slowest-drying colors. This narrows the  range  of drying times within a line of paint, but, even with  these  driers,  some  colors' drying times may differ from others by several days to several weeks.

Natural and synthetic resins are also used to narrow the range of drying times further. Winsor & Newton has accomplished this in its alkyd paints by using an oil-modified alkyd in which it grinds its pigments. The Schmincke Company has narrowed the range of drying times by using a resin-oil formulation specific for each pigment in its Mussini paint. However, these two paints are unique. Most  other brands of oil paint have a large gap in drying  time between  certain  colors and caution in their combined use may be necessary.

In general, a faster-drying  paint should  never be applied over a slower-drying paint; otherwise cracking may result. Some of the slowest-drying colors not rec­ ommended for underpainting are all carbon-based blacks  (ivory,  lamp,  carbon, and charcoal black), all cadmium-based paints (cadmium red, cadmium yellow, cadmium green), vermilion, alizarin crimson, zinc white, and Vandyke brown. These colors, unless modified by the artist or the manufacturer, can take between three and five days in a thin paint film to dry.

Among the faster-drying colors are the cobalt-based colors (such as cobalt yellow, cobalt blue, and aureolin), manganese-based colors (manganese blue, manganese violet, and manganese black), raw and burnt  umber  (both  contain large amounts of manganese), prussian blue, and lead-based whites and colors (including flake white, cremnitz white, Naples yellow, chrome red, and chrome yellow). Some colors, such as the manganese-based colors, have a strong  cata­  lytic effect upon drying oils and are often ground into poppy oil in order  to slow the drying time.

Each manufacturer does or does not adjust the drying rates of its colors according to its own idiosyncrasies, and  most do not  supply  information  about the drying times or the film characteristic of their colors. Because of the varia­ tions, generalization will often not be discovered until after use. An understand­  ing of the nature of pigments,  combined  with knowledge  of  the  pigments  used by a manufacturer to produce a particular color, will help you to infer a drying rate. In addition to modifying  drying times through  the use of  media, a painter  can accomplish the same goal by mixing slow-drying colors with  fast-drying colors. 

 

FILM CHARACTERISTICS

In addition to varying drying times among pigments, there are also varying film characteristics, which can range from tough and flexible to hard and  brittle.  It is the brittle film characteristics that are of greatest concern, particularly  when  used in underpainting. If a brittle paint is used underneath, it may cause the over­ painting to crack.

Zinc-based paints, such as zinc white, are the most brittle and are not recom­ mended for use in underpainting. Cobalt-based colors, barium yellow, strontium yellow, and red oxides, although not as brittle as zinc paints, are also not recom­ mended for use in underpainting. Lead-based paints,  raw  umber,  and  burnt  umber are among the most flexible paints and are perfect not only for under­ painting, but also for mixing with more brittle paints to stabilize them.

 

STABILIZERS

Ideally, little or no stabilizer should be used in an artist-grade paint. There are certain pigments, when ground into linseed or poppy oil, that could either have a stringy consistency or a tendency to separate from the oil. Such  stabilizers  as waxes (beeswax or aluminum stearate), water, and  alumina  hydrate  (added  to give bulk) are currently utilized to regulate consistency. Although there are defi­ nitely cases where it is more helpful  than  harmful  to  have  these additives,  the use of these materials has been abused.  Consistency  is  often  mistaken  for quality, and it is certainly more profitable for a manufacturer to use stabilizers rather than pigment to meet the artist's expectations

.

Stabilizers easily cross over into use as fillers. It is considered acceptable  by most manufacturers to use, for example, as much as I to 2 percent aluminum stearate, by weight, to improve the consistency of some colors. However, alumi­ num stearate weighs very little compared to the volume it can  occupy.  Alumi­num stearate does to oil paint what goose down does to a comforter; it is easily possible for this wax to take two to four times its weight in volume. If  an  "average" tube oil paint consists of 50 percent oil to 50 percent pigment  by  volume, the adding of 2 percent aluminum stearate, by weight, could reduce the amount of pigment by volume by 8 percent to 42 percent. Although certainly significant, this is not serious. It becomes serious when more than 2 percent by weight is used, not only because it replaces more  pigment,  but  because  it becomes necessary to increase the proportion of oil to offset the increased effects  of the aluminum stearate. If  5  percent aluminum  stearate,  by  weight,  is used,  it is quite possible to end up with volumes of 70 percent oil, 20 percent aluminum stearate, and only JO percent pigment.

It is rare to see this kind of abuse in artist-grade  paints  because  most  of  the cost of making these paints is for labor and  not for materials.  Most  manufactur­ ers of such paints find it pointless to scrimp on raw materials. In lesser grades, however, where competitive pricing is so important, the quantity and quality of labor and raw materials are reduced and one of the most effective ways to accomplish both is to increase the use of a stabilizer like aluminum stearate. The artist can sometimes detect the excessive use of stabilizers by doing a tinting strength test. 

OIL SEPARATION FROM PIGMENT

The separation of oil and pigment in an artist-grade paint does not necessarily indicate poor quality; it often means that little or no stabilizer was used.  How­ ever, it can also indicate the lack of aging, lack of resin (natural or synthetic), or lack of modem grinding techniques, none of which would necessarily be serious drawbacks.

Separation commonly occurs in pigments containing cobalt, manganese, cad­ mium, and lead and appears to be due to an aging process whereby the surface tension of certain pigments is reduced  with age, which results in a lesser amount  of oil being needed to coat a particle. The excess oil is naturally expressed and causes the .apparent separation. It is not uncommon to find an "old time" painter looking for old tubes of paint, rather than "fresh"  tubes,  because  the  aging process improves the quality of oil paint (as long as  the  container  is closed). Some of the finer quality paints are aged up to six months  to allow  this separa­ tion to occur before packaging.

The separation of oil and pigment in lesser quality  oil  paints  often indicates that too much oil was used in the manufacture. This would be especially true of paints in which stabilizers are commonly used to compensate for excessive oil.

 
DIFFERENT GRADES OF PAINTS

Three grades of paint seem to have developed in the United States: artist (finest, extra-fine, super-fine), amateur (fine, professional), and student. The European products that are available in the United States are often of two grades: artist and student. Many of the European student-grade paints are equivalent in quality to American amateur-grade paint.

In general, artist-grade paints are supposed to be made with only the purest, highest-quality ingredients, without regard to cost. The paint is manufactured according to the tradition that each company has established for itself and upon which it rests its reputation. Amateur-grade paints are made from the best ingre­ dients that can be found at a reasonable price. The level  of  craftsmanship,  although not as fine as in artist-grade paint, is sufficient to produce a consistently good-quality paint that is still safe for professional use. Student-grade  paint made in the United States is designed to be used for studies or learning exercises  that  will most likely be discarded. Therefore, this paint is made with  the least costly raw materials and with the most cost-effective methods. Within each of these grades there are also varying levels of quality.

To complicate matters, some companies have recently begun to call their ama­ teur grade "Professional," a term that seems to imply some equivalence with artist-grade paint. The best way to avoid being confused by  all  this is to learn about the pigments that are used to make paint. For example, the finest cadmium red paint is made only from the purest cadmium sulfo-selenide (PR 108, C.I. 77196),  and  not  from  such  cadmium-barium sulfo-selenide mixtures  as PR 108, C.I.  77202,  which  contains  less  than  15  percent  barium  sulfate,  or  PR 108:1, C.I. 77202, which contains more than 15 percent barium sulfate. Such cadmium­ barium mixtures fit into the amateur grade because they tend to be weaker in intensity and  the paint  is more  transparent  depending  on the amount  of barium sulfate filler. Cadmium red hue, which is mostly found in student-grade, and occasionally in amateur-grade, paints is made with azo red pigments. It is a less expensive alternative to the cadmium pigments, but has a slightly unnatural appearance and, when mixed with azo yellow pigments, produces a dull orange. When you have this information, you can make an educated  choice.  You may even choose the azo-pigmented color over the cadmium-barium color for  a esthetic reasons. Price may be a factor in making your decision as well,  because the finest cadmium red paint is expensive. If  you  paint  large  pictures,  which have to be viewed twenty to thirty feet away, the difference in the quality of the paint you select may not be seen.

In amateur and student grades of paint, the hue of expensive pigments may be imitated by using mixtures of less costly pigments. Cobalt blue, for example, is often simulated using mixtures of phthalocyanine blue and white. This kind of mixture looks similar in surface hue to the actual pigment, but it is opaque and duller than genuine cobalt blue. When mixed with other  colors,  the  imitation tends to muddy the appearance.

Student-grade paints are not, and should not be, used for professional work. Making a choice between amateur-grade and artist-grade can simply be based on whether you can or cannot see the difference. The difference in quality is most obvious in such colors as manganese blue, cobalt violet, cadmium red, and Van­ dyke brown. A comparison of one or more of these colors can be made by spreading some of each color on a sheet of  glass  with  your  fingertips.  (Wash your hands thoroughly afterward.) If you cannot see, feel, or care about the difference, then it is pointless to buy the more expensive paint.

 

LARGE TUBES AND CANS OF OIL PAINTS

The renewal of interest in oil painting, particularly large oil paintings,  has fos­ tered interest in larger and more economical volumes of paint. A few companies have offered larger volumes of paint for some time. LeFranc & Bourgeois, for example, markets 250 ml tubes of the more popular colors of its 104 series (its second-grade, or amateur-grade, paint). In the past few  years,  small manufactur­ ers have begun to produce cans or jars of oil paint. Recently, larger  manufactur­ ers, including Grumbacher, Martin/Weber, Maimeri,  and  Winsor  &  Newton, have entered this market, too.

The range in quality from brand to brand is great, and the lure of  large  vol­ umes and low prices has led many artists to buy paints for expediency without checking the label or comparing quality. Most major oil paint manufacturers produce several grades of paint to cover  the  potential  marketplace.  At this time, no company is packaging its finest paints in large volume because even with the savings such paints in large quantities would still not be affordable  for the aver­  age artist. What is being offered is either a second  grade,  also  called  profes­ sional grade, or the manufacturer's student grade. In some cases.  a  new.  even lower quality than student grade is made to fill these large tubes.

These new large tubes, jars, and cans have to be looked  at and  tested  carefully. Some of these paints are labeled Cadmium Red (Hue) when actually three separate pigments are used to make a simulated color, none of them cadmium and one of them white. Even if you ignore the potential permanency of tertiary colors such as these, the mixing properties would be absurd. I particularly rec­ ommend that any paint that is a student grade or less should not be used profes­ sionally. Student-grade paints are for exercises and experiments where the final work is not sold. There is good quality, large-volume paint available at a sub­ stantial savings, but you must become an educated consumer to find it.

MIXING BRANDS AND GRADES

There are no precautions necessary when mixing different brands or levels of the same quality of oil paint. However, mixing an artist-grade paint with a student­ grade paint does not give birth to an amateur-grade paint.  In fact, few  painters  mix levels of quality. It is most common to underpaint  with  an  amateur-grade paint and save the more expensive, better-quality, artist-grade paint for the final stages. This is a safe method of economizing.

The mixing of different brands of paint within the same level of  quality, although perfectly safe, is not as common as might be imagined. Most painters develop a brand loyalty, and behave as if they were cheating on a lover when an interesting or unusual color is found in another brand. To put such attitudes in perspective it would be helpful to understand that although there are definite distinctions among brands, such distinctions are not so great that they  should inhibit selections.

 

COLOR RANGE

In an artist-grade paint it is not  uncommon  to find  as many  as a  hundred  and fifty different colors. Approximately one-third of the colors is made using indi­ vidual pigments in their natural state. Another one-third of the colors is the same pigments chemically or mechanically (grinding) modified to  change  the  color. The remaining one-third is colors produced through mixing two or  more  pig­ ments together. In lesser grades of oil paint,  the color  range  often  consists  of only thirty-five to fifty colors, which rely heavily on mixtures of  pigments  to obtain much of the range.

It is a common misunderstanding among inexperienced painters that most  of these colors can be duplicated with the use of a "good red, yellow, and blue." Although the final one-third of a color line can often be duplicated easily with a palette of colors consisting of one warm and one cool of each  of  blue,  red,·  yellow, and violet with some additional help of white and  black,  the qualities of  the other colors cannot be duplicated by  mixing.  Surface color, or hue, can  often be made similar to the other two-thirds of a color line, but depth and brilliance cannot. Secondary (two colors mixed) and tertiary  (three colors mixed) colors do not function well as tinting colors, often muddying  the appearance  of other col­ ors. One example of this is cobalt blue hue, manufactured by some paint com­ panies to simulate the more expensive cobalt blue.  While  the hue resembles  the real thing in surface appearance, it is duller and is opaque, not transparent.

Experienced painters usually try to buy a needed color rather than mix it, and they try to use it in its purest form whenever possible. Consequently, large color lines exist primarily because of the demands of  the  painter rather  than  because the manufacturers are looking for something else to sell.

WHITES

In most painting techniques one-half the amount  of paint used is white. The type  of white, or the combination of  whites,  used  plays  a large  role in  determining the appearance of a work. There are three basic kinds of white-lead, zinc, and titanium.

Flake White is lead  carbonate that has been ground  into poppy or safflower oil  (to slow the drying time and reduce yellowing) and to which a small amount  of zinc is often added to improve consistency.  Flake  white  has  the  greatest durability and is the most flexible of all the  whites.  It is not as  white  as zinc  white nor as opaque as titanium, but is excellent  for  making  tints  of  cooler colors, and can safely be used in underpainting.  It is poisonous  if  ingested  or if the powdered form is inhaled, but not through skin contact. Flake white  can blacken if it is left unprotected against hydrogen sulfide, an atmospheric  pollu­ tant, so varnishing is a must.

Cremnitz White is the same as flake white but without the zinc additive. Its consistency is a bit drier and stiffer, and  it  is  preferred  by  purists.  Cremnitz white and flake white used to be known for yellowing because of linseed oil, but linseed oil is rare!y used in making this paint today.

Foundation White, which is produced by a few manufacturers, is also lead carbonate, but this is ground into linseed rather than poppy or safflower oil. The paint films formed by poppy and  safflower  oils are not  as strong or flexible  as  the film formed by linseed oil, and would not be as safe to use as a  painting ground. Foundation white is specifically designed as a painting ground.

Zinc White, which was originally developed as a  nonpoisonous  alternative  to lead carbonate, is effective but not as versatile. Zinc  white is zinc oxide ground  into poppy or safflower oil. It is the least opaque  of  all  the  whites and  is ideal  for tinting and glazing. It is not darkened by hydrogen sulfide. The major draw­ back of zinc white is its brittleness and, because of this, it cannot be used as a ground or in underpainting.

Titanium White is titanium dioxide ground into poppy or safflower oil (some­ times a portion of linseed  oil is used).  It is the most opaque and  the whitest  of  the whites and, in its pure state,  it can reflect  more  than  97  percent  of  all light. It is also the newest and now the most popular of all whites. The permanency  rating is among the highest given to a pigment.

Blends of Whites are produced by several manufacturers. The most popular is a blend of zinc and titanium. Permalba white, produced by the Weber Company, is among the most popular of the available blends.

 

OIL PAINTS VERSUS OTHER PAINTING MEDIA

It is easier to learn how to paint with oils than with  most other  media.  At the same time, it is the most difficult of media to master, primarily because it is so versatile. There are so many styles of painting, formulas for media, pigments, and tools in oil painting that many find they do not have the patience necessary to master this medium. There are many quicker, less complicated media of expression, but, with the exception of egg tempera, none is as rich or as time­ tested as oils.

Oils are most often compared with acrylics. Although acrylics were developed for artist use only forty years ago,  this  medium  has taken  over a large share of  the artists' materials market. Many painters  have begun  in, or switched  to, acry­ lic because of the lower costs, availability in larger volumes, fast drying, easy clean-up, absence of hazardous thinners, and nonyellowing characteristics. Nevertheless, I have yet to hear anyone say that  he  or she  uses acrylics  rather than oils because they look better. In general, acrylics are primarily used as an alternative to oil.

The nature of acrylics prevents them from being as concentrated with pigments as oil paints, or as brilliant in appearance.  Some  pigments  traditionally  used  in oil paint are not  used  in acrylics  because their unique qualities cannot  be seen in a polymer medium. The available color range of acrylics is  narrower  because many pigments cannot survive the alkalinity or cannot stay in suspension. Acry­ lics have only a narrow range of available media, and  are  therefore  less  ver­ satile. They also dry with a much darker appearance  than  the  wet color,  which can be deceiving for the beginner. If acrylics  were compared  to the classification of grade levels used for oils, they would fit the amateur grade.

The only other medium that has often been compared with oil painting is egg tempera. When used properly, it can be more brilliant, luminous,  nonyellowing, and permanent than oils. However,  the  techniques  for  egg  tempera  are  even  more difficult to master, and it is a more fragile medium.

OIL PAINTS AND OTHER PAINTING MEDIA

Although water-based paints, such as acrylics and vinyls, should not be painted over any oil-based paint, oil-based paints can safely be painted over water-based polymer emulsion paints. This has been verified  by manufacturers  of  both types of paint. Because of reasons involving economy and drying time, it has become common to underpaint with acrylic and finish with oil paint.

The use of wax in encaustic painting is a  long-established,  safe  painting method. However, there have been some problems in the use of encaustic paints and oil paints within the same painting. Paintings in which oil paint has been applied over areas consisting of high proportions of wax have cracked and some­ times the paint has fallen off the surface. Wax appears to dry quickly, but,  in reality, it only sets up quickly, for it  takes  years  to  cure,  certainly  far  longer than the oil paint applied over it. This would violate the rule of never applying a faster-drying paint over a slower-drying paint.

 

The  use  of  encaustic  should  not be a start-and-stop operation. Once wax is used,  it is  safer  to  finish  with  wax and not with oil.

 

The  mixing  of  such  drawing  materials  as  pastels,  paint  sticks,  and  crayons with oil painting has become popular. Materials such as these should be reserved for the final stages of a painting. Oil  pastels,  crayons,  and paint sticks are made  of wax and pigment and should be treated as an encaustic  paint.  There  is one  paint stick  made by Edding Company  that is an acrylic,  lacquer-based  paint stick that behaves more like a paint than a  wax.  This quality  would  make it safer  to use in underpainting. Soft pastels are more difficult to use safely because of their chalky nature, which can give unpredictable results. However, charcoal has tra­ ditionally been used for preliminary, light sketching on the canvas before the painting is started, and can be used safely in moderation if the charcoal is fixed before the application of oil paint.

Although the use of mixed media can be a powerful method  of  expression, many an art conservator has had to repair works in which materials were thrown together carelessIy.

 

THE ROLE OF MEDIA IN OIL PAINTING

A medium is a recipe that includes, in specific proportions,  two  or  more  of: drying oil(s), resin(s), drier(s),  wax(es),  and  thinner(s).  A  medium,  in  addition to regulating the consistency of the paint, thinning or thickening it, will also regulate the drying time, transparency,  gloss,  and  leveling  characteristics,  as well as improve the overall aesthetic appearance.

If you are glazing without a thickener, such as Venice turpentine, for example, the thinned paint will simply run down the canvas. If the various drying times between differing pigments are a problem, this can  often  be  resolved  with  the use of a medium formulated to narrow the drying time. Sometimes the impres­ sions left by brushstrokes are undesirable, and can be made to disappear by substituting stand oil for refined linseed  oil.  Depth,  brilliance,  and subtlety  are all controlled by such resins as darnar, mastic, and venice turpentine.  More than one medium may be used in the course of a painting's development, and each  would be used at different stages. (This  is discussed further  in Media,  Solvents,  and Varnishes, pages 251 to 273.)

Oil painting without media, or with only linseed oil and turpentine, is  like placing  an order at a French  restaurant  for  boiled duck,  no sauce,  no salt, and no butter. An appropriate medium does for oils what a French chef does to an otherwise  bland  and greasy  dead  bird,  and the results, like Duck a !'Orange,  are exquisite.

 

HAZARDS

Although hazards are discussed in depth in the chapter on hazards, it is important to stress here that the primary danger in working with  oil paints lies with the use of thinners and the seemingly miraculous ways  that  painters seem to ingest and inhale paint without "eating" it.

Turpentine, until recently, had been thought to  be  one  of  the  safer  thinners that an artist could use, but now it has  been  rediscovered  that  turpentine  can enter the body not only by inhalation, but through the skin. I say rediscovered because during the nineteenth century turpentine was used  as liniment  to carry herb and other remedies into and through the skin. Today, it seems to be a big surprise to everyone in the artists' materials  trade  that  turpentine  can  pass through the skin. There have been reports of kidney damage and changes in the bone marrow in a very small percentage of painters  who  were said  to be using this thinner as any average painter would. Even worse is the physical damage to painters who use industrial thinners, which often contain far more hazardous chemicals.

It has been common to see painters having lunch, smoking, and  biting  their nails, with paint on their hands, in the folds of their skin, and caught under their nails. There are also artists who airbrush in their living space or in their studio without adequate ventilation, protective clothing, or breathing apparatus. An all­ too-common response to the hazards of oil paints, from many of these same individuals, is "I'm not stupid, I don't eat my paints!"

Common sense, good work habits, and some basic knowledge  about the haz­ ards concerning the materials you use could save your  life  or,  at  least,  the quality of your life.

Palettes

Techologcal and chemical advances over the past few centuries have enabled the manufacture of an increasing variety of colors in oil paints. The following lists give some indication of how the spectrum of colors has expanded, and also suggest a basic selection for the contemporary artist.

 

COLORS AVAILABLE DURING REMBRANDT'S LIFETIME

Vemillion

Red Lead (replaced by Cadmium Red) Madder

Umber (although available, it was more often mixed) Sienna.

Ochre

Green Earth

Realgar (an arsenic orange, not used since the Renaissance)

Orpiment (an arsenic yellow, not used since the Renaissance)

Malachite Green (fell into disuse after the eighteenth century) Ultramarine

Azurite (replaced by Cobalt Blue in the eighteenth century) Indigo

Ivory Black Lead White  

 

COLORS AVAILABLE TO THE IMPRESSIONISTS

Alizarin Crimson       Zinc Yellow            Emerald Green Vermilion     Aureolin (Cobalt Yellow)         

Chrome Red             Sienna, Burnt and Raw     Artificial Ultramarine Madder  and Rose Madder       

Umber,  Burnt and Raw       Cobalt Blue        Indian  Red           Vandyck Brown     Cerulean        Cadmium Yellow            

Prussian Blue (pale,  middle,  and  deep)               Malachite Green        Cobalt Violet Chrome Yellow       

Yellow Ochre           Permanent  Green  Deep       Lead White           Viridian Ivory Black

Naples Yellow         Chromium  Oxide  Green       Zinc White          Chrome Green        Green  Earth

Barium Yellow         Cobalt Green

 

A SUGGESTED CONTEMPORARY PALETTE

Lemon Yellow                         Cobalt Blue          Indian Red     Cadmium  Red  Light               

 Ultramarine  Blue                  Burnt Sienna        Burnt Umber

Cadmium Yellow                    Phthalocyanine Blue              Cadmium Yellow Light

Alizarin Crimson                      Phthalocyanine Green           Mars Black

Chromium Oxide Green         Lead White                   Viridian Ivory Black Cadmium Red

Cobalt Violet                            Yellow Ochre              Titanium White

 
A SUGGESTED BEGINNER'S, OR ABBREVIATED, PALETTE

 

Lemon Yellow

Cadmium Yellow

Alizarin Crimson

Cadmium Red

Cobalt Blue

Ultramarine Blue

Viridian Yellow Ochre Burnt Sienna Burnt Umber Ivory Black

Titanium White

The contents of this site were previously published in "ART HARDWARE" by Steven Saitzyk 1987, © COPYRIGHT