FRAMING AND STORAGE
For the artist, and collector the primary purpose of picture framing is to protect artwork, which is often an expensive proposition. In the past, mostly for economic reasons, protecting the artwork was often given a low priority and, in some cases, even ignored. Recent lawsuits, however, involving the deterioration of artwork through improper framing and storage have helped put things back into perspective.
Artwork, if it is to have a reasonable chance of surviving decades or even generations, needs to be protected from acid air pollution, acid migration, mold, excessive humidity, ultraviolet light, infrared light, dramatic changes in temperature, insects, and metals such as iron and copper. Attempting to protect artwork from all these things is difficult, even for a museum with unlimited funds. Deciding what is reasonable protection for a particular piece of artwork that you have created or collected involves balancing various levels of protection against economic necessities. Complete protection can cost more than the current as well as the future value of the artwork. The level and type of protection selected should, therefore, be based on the type of damage that is most likely to occur. For example, framing an oil painting executed on canvas with a sheet of ultraviolet-light-filtering acrylic when the artwork will be exposed only to normal room lighting seems extreme. Since more artwork is seriously damaged by being framed or stored in contact with nonarchival materials, it would seem this area should have the highest priority. Conservation framing, particularly with artwork executed on paper, can create an almost self-contained environment that provides reasonable protection against the most common hazards like acid pollutants, acid migration, mold, and insects. I have compiled several rules, as well as reasons for the rules, which relate to the proper protection of paintings and drawings. If these guidelines are followed or modified, with common sense, to your own needs, your artwork should be reasonably protected. I have also supplied the latest technical information about the materials used for framing.
It is important to understand that the whole area of conservation framing, particularly of paper, has developed only recently. New materials for framing and conservation are being invented all the time, and guidelines for their use are constantly redefined. Until the nineteenth century, when papermaking machinery was invented, paper was not a material commonly available to artists. This invention made paper easily affordable and profitable for the first time. What followed was a great conversion of papermaking materials from primarily rag and linen to ground-wood pulp, which was sized with an alum-rosin combination. This conversion to less permanent and highly acidic materials peaked during the 1860s and its significance did not become clear until the turn of the century. Prevention and cures for the problems associated with the use of these materials were slow to develop, and it was not until the late 1960s that information on conservation framing began to appear in trade magazines for framers and artists. Unfortunately, most framers, as well as most artists, have not kept up to date and continue to use materials improperly or to use the wrong materials altogether. It is therefore entirely possible to find a frame shop that has been owned for generations by the same family producing fine-looking framing, yet using materials that not only do not protect the artwork but accelerate the aging process.
If you are not already a picture framer, this chapter is not designed to turn you into one. However, if you are an artist who wishes to protect your artwork properly, or a collector wishing to protect your collection, this chapter will help you understand the logic behind why and how certain materials and procedures are used in framing and storage.
Rules Concerning Paper Art
Matting was originally developed as a method of protecting artwork by isolating the surface of the artwork from the surface of the glass, as well as away from the edge of the wood frame.
This is important because the glass tends to condense moisture and provide an ideal environment for mold to grow on the surface of the artwork. Also, wood becomes increasingly acidic over a period of time and acid migration can occur to the artwork. It was some time after its functional invention that the decorative qualities of matting seemed to overcome the original purpose. If a mat is considered undesirable for whatever reason, some means of separating the surface of the artwork from the surface of the glass is still necessary. Setting he artwork back away from the glass can be accomplished by using a wood or plastic spacer of approximately ¼ inch along the frame between the backing and the glass.
In setback framing, I mount the backing board to the support board, because I have seen too many backing boards creep out from the edge of the setback material. This happens because of mishandling or the natural expansion and con traction that these boards may undergo with changes in humidity. Particularly with setback framing, contemporary galleries often frame with wooden support bars built into the back of the picture frame for added strength.
This is often necessary for frames that are large and/or will be handled a great deal. Support bars are a particularly good idea when glazing with clear acrylic sheeting in larger sizes because plastic sheeting tends to bow and can pop out of a picture frame.
The following rules apply to most paper, fabric, and any work that needs to be protected from the atmosphere and mechanical abuse.
1. Never mount permanently any valuable or potentially valuable artwork, unless the artwork requires the support, such as a collage or a piece of artwork that cannot support its own weight. If it cannot be held in two places without risk of tearing or distortion, it should be considered for mounting. If you do choose to mount, you should regard the artwork and the mounting board as one piece permanently.
The definition of conservation mounting seems to be undergoing some revision. The old definition is that the adhesive should be pH neutral, water reversible, and of vegetable origin. The original reason behind the use of vegetable based adhesive was that other pastes were of animal origin and tended to become acidic as they aged as well as less reversible with water. The pH neutrality is important because acidity breaks down cellulose and weakens the paper. If there are lignins (the natural glues that hold plant cells together) still present in the paper, the paper will tum brown. Acidity can also affect many dyes and pigments dramatically by changing their colors. Recent studies show that an adhesive may appear to be pH neutral to start with, but that there are no guaran tees it will remain so over many years. Reversibility with water was important to conservators because the adhesive could easily be washed out without damaging the artwork. Today, however, a large variety of materials may be used to pro duce a piece of artwork. There are many pieces that would be destroyed or seriously altered if washed in water but would not be if washed in other solvents. Finally, there are now chemical adhesives that indicate the possibility of aging characteristics equivalent to vegetable-origin adhesives.
So, you may ask, "What do I do?" If you must mount the picture, decide which will affect your artwork the least-water or organic solvents. Watercolors, for example, would be affected less by organic solvents, while etchings would be less affected by water, if removal of the artwork from the support became necessary in the future. Select an adhesive that has a good record for nonyellowing and for maintaining pH neutrality over time, and that will be least harmful to your artwork if you have to remove it.
2. Never use pressure sensitive tapes, such as masking, drafting, magic, surgical, and packing tapes. All these tapes will self-destruct and severely damage artwork wherever it is touched by the tape. There are currently only two exceptions to this rule-tapes produced under the name Filmoplast by Hans Neschen GmbH & Company in Germany and Archival Aids Document Repair Tape made by Ademco Products in England.
3. Never secure artwork in more than two places. Exceptions to this rule should be made only with extremely wide pieces and with the understanding that for every additional place the artwork is secured you risk having twice the number of ripples. This is because the natural expansion and contraction of paper from variations in temperature and humidity will be restricted. Recommended methods for securing artwork will be discussed later.
4. Never use any ground-wood pulp-board or paper, chipboard, or cardboard as backing or storage for artwork. These boards, especially corrugated card board and chipboard, are highly acidic, contain iron and copper, and have been known to damage artwork, even without direct contact. The acids can even bleed through four-ply museum boards.
5. Never use conventional wood pulp boards for matting or backing of original or valuable artwork. Instead, use museum or conservation boards. Unless the boards are of 100 percent rag or are of lignin-free alpha wood pulp that has been buffered to remain acid-free, they will damage the artwork. Such damage can be seem as soon as six months, and may in some cases be irreversible. Pulp boards may be used only if they are not in direct contact with the artwork and are separated by a four-ply museum or conservation board. With matting, the edge of museum board should extend at least ¼ inch past the edge of the wood-pulp board to prevent any acids in the wood-pulp board from cascading over the edge of the museum board.
6. Never use single-strength glass larger than 36" x 48". If you have not already guessed the reasoning behind this rule, you should first consult an insurance agent regarding the extent of your insurance coverage.
7. Never glaze with acrylic sheeting for artwork done in charcoals and/or pastels. Plastic sheeting can develop a powerful static electrical charge and can lift a significant amount of material off the paper on to the plastic surface. You should also be aware of the fire hazards of plastic sheeting and its ability to give off poisonous gases when burning with insufficient oxygen.
8. Never put original or valuable artwork, especially glossy photographs and acrylic paintings, in direct contact with the glass in a picture frame. Glass tends to collect moisture on its surface, and when it comes in contact with the surface of paper artwork it can provide an ideal environment for the growth of mold. Foxing, which is the appearance of small brown spots on artwork, is most often attributed to mold. However, foxing can also be caused by iron deposits in reprocessed wood-pulp backing boards. Photographs and acrylic paints, primarily due to the nature of their surface films, tend to adhere to glass over a period of time and the surface of the artwork can be damaged if the picture has to be removed.
9. Never allow the edges of a piece of artwork to touch the edge of a wood frame. Wood has lignin, which breaks down and becomes acidic. Moreover, many woods, such as oak, are naturally highly acidic. The artwork should be at least ¼ inch away from the edge of the wood.
10. Never cut, trim, or in any way alter an original piece of artwork without the clear consent of the owner. In California, it is a violation of the law even for the owner to alter a recognized piece of artwork without the consent of the artist! California passed the Art Preservation Act of 1979, which was amended in 1982 and became the model for similar acts in New York and Massachusetts. The law provides for actual and punitive damages as well as attorneys' fees for willful disfigurement or destruction of fine artwork.
11. Leave restoration to a recognized professional restorer. Most professional restorers spend a great deal of their time correcting the work of self-appointed amateurs.
Rules Concerning Art on Canvas and Panels
Artwork done with oil paint or acrylic is usually painted on a support of stretched or mounted canvas. In a small percentage of cases it is painted on wood or metal panels. This type of artwork, if properly varnished, does not have to be framed with glass because the surface is more easily cleaned and is less subject to permanent damage from mechanical disturbances. Nevertheless, a certain amount of additional protection is needed, which can be supplied by the edge of the moulding used to make the picture frame. The moulding covers the edge of the painting and protrudes above the surface of the painting. This helps to protect against the most common form of mechanical abuses and problems in handling.
Paper artwork, from the outset of its development, was framed for protection first and for decoration second. This is not true in the case of early frescoes and paintings done on panels. The earliest picture frames were made to create a focal point or atmosphere in which the artwork could be seen. The oldest known frames were doorways or archways that served as a focal point through which to view a scene or to outline some architecture, as well as serving as an entrance or exit. Today, a carpenter's term for the process of installing a door is still "framing a door." It was not until the late seventeenth century, when painting had developed the technology to be portable, that the notion of protection came to be a major consideration. The following rules apply to art on canvas and panels with oil paints or acrylics.
1. Never attempt a perfect fit; you must leave sufficient breathing space for expansion and contraction of the artwork and the materials used in framing it. The standard allowance for paper art with glass is 1/16 inch and for stretched art it is 1/8 inch if possible. Some commercial mouldings, because of the width of the "rabbet" (the lip of the moulding into which the artwork is installed), do not allow for 1/8 inch and you may have to settle for 3 /32 inch to prevent the edge of the picture from showing. The larger allowance is recommended because stretched artwork is not sealed from atmospheric conditions and is more subject to variations in temperature and humidity. In addition, the wood or metal used as a support for the paint is rarely the same as that used for the frame. Consequently, each will expand and contract differently and will need the allowance so that one does not restrict the other and lead to warping and damage.
2, Never nail, toe nail, staple, or screw into or through a canvas support to secure a picture to a frame. Do not do anything that rigidly locks the two together. After you have given an appropriate allowance, you should not defeat it by locking the picture to the picture frame or weaken the support by drilling or nailing. One desirable method employs flat metal strips that attach to the frame at one end, while the opposite end can be bent over the back of the stretcher bars or the back edge of the panel, as shown in the illustration above. These strips should be strong enough, after being bent into shape, to act like springs to hold the artwork into the frame with pressure.
Another method employs triangular steel spring wire clips (see the illustration right), which if used in a similar manner will accomplish the same results.
There are two advantages to this method of installation. One is that the picture is secured, but still allows for expansion and contraction. The other is that the spring clips or metal strips can be swiveled in or out of place and the picture can be installed or removed easily without damage to it or to the frame.
3. Never put the surface of a valuable piece of artwork directly against wood moulding; use strips of four-ply museum board or felt to isolate the two. It is possible that the finish, gilding, or even bits of wood might adhere to the surface of the painting. Most conservators feel that although the felt or museum board may also adhere to the surface, it is easier to remove from the artwork without damage.
4. Never put screw eyes into the support or the auxiliary support of the painting, but into the frame. It is popular today to use thin mouldings to frame paintings. This makes this rule difficult to comply with. If the painting is very heavy, and the auxiliary support is required to bear the weight of the frame as well as itself, it may warp.
Even if weight is not a serious problem, the installation of screw eyes or brackets may weaken the support. However, if you must screw or nail, drill first carefully before screwing them in so that the auxiliary support does not split.
5. Never attempt to restretch an old canvas or unwarp an old panel. This comes under the heading of restoration. As a painting ages and the paint film becomes more brittle, all mechanical adjustments can produce fine cracks that may not be seen at first. These cracks will inevitably become larger and more serious. A professional restorer knows how to soften the paint film carefully to make the necessary adjustments slowly. If the painting is still in the earlier stages of curing (three months to one year), adjustments may be made with less risk. This may be done by warming the unstretched painting on the back with an iron, set on low, to soften the paint film, but be aware that this will rob the painting of some of its life. Then the painting may be stretched, but not too tightly. Whenever possible I do this part by hand, because pliers may exert too much tension, especially on small canvases.
ADDITIONAL NOTES ABOUT STRETCHED ARTWORK
Should the back of a stretched canvas painting be sealed? A stretched work must breathe, so sealing the back can seal in moisture and dust, which may lead to mildew. Sealing also prevents easy inspection for the many problems that can arise. Nevertheless, the greatest dangers to a stretched artwork are dents, perforations, and tears from accidents and mishandling. If you feel that you need the extra protection of a backing, there is one method you should consider. Select a thin board---<:chipboard, masonite, or plywood, drill holes in it for air circulation, and place gauze over the holes to prevent dust from entering. This backing can be fastened to the frame along with the painting either by using spring clips, or by installing a strainer as shown below.
Stretcher bar keys are little triangular pieces of wood, which are placed into the inside corner spaces of the stretcher bars and are tapped into place to force open the corners. This creates slightly more tension, which will remove sagging and wrinkles. Before hitting the keys, put a piece of cardboard between the canvas and the stretcher bars. If you slip, you will not damage the painting. Remove the protective cardboard pieces after you have adjusted the keys. On older paintings, even small dents may lead to serious cracks over the years. Just because you cannot see damage now does not mean it has not taken place. After
your protective board is in place, give the keys a few gentle taps. If the wrinkles do not come out easily, give up!
Although it is rare that stretcher bar keys can fall out and locate themselves between the inside of the canvas and the stretcher bar, most conservators will take some precaution against this. There are two methods. The first one is to place tiny screw eyes in the keys and support bars and connect them with wire. The other is simply to tape them to the stretcher bars. The tape method is riskier because most pressure-sensitive tape adhesives age poorly, weaken, and fail.
In the following, the properties and proper uses of the primary material used in framing are explained. There are two basic methods of mounting artwork, and various materials are available for each method. Also discussed are the types of glass, plastic, and moulding that can be used in picture framing.
A mounting system is a method of holding a piece of artwork in place. Artwork can either be hinged, which involves attaching it loosely so that it can easily be removed, or glued flat.
Hinge Mounting has the function of securing the artwork either to the backing board or to the mat board without permanently altering the artwork. Hinges should also be removable with either water or a small amount of alcohol. A hinge should be made of a stable material with sufficient strength to hold the artwork in place, yet it should tear free if the picture is dropped. The reasoning behind this is that it is better for the hinge to tear than for the artwork to tear. The most common materials used for hinges are Japanese rice papers, archival pressure-sensitive tapes, and linen tape.
Japanese papers made from the traditional fibers have been known for their pH neutrality, strength, lightness in weight, and excellent aging characteristics. Today, however, most Japanese papers are no longer made from only the bast fiber of kozo, mitsumata, or mulberry. Sulfite pulp is commonly used as a filler in many of the traditional papers and, in some instances, the paper is all sulfite pulp. It is therefore important to establish the content of the Japanese paper when selecting it to use as a hinge for fine artwork.
One reason the Japanese papers are selected for making hinges is that when they are hand tom they give a frayed edge. When attached to the back of art work, this kind of edge tends to show less on the front side. The adhesion of the artwork to the hinge is accomplished with the use of a water-based adhesive, such as the one described below. Careful control of the amount of paste is important or the moisture may deform the paper, which will show up as little bumps on the front side of the artwork.
The following is a recipe for the preparation of a wheat- or rice-starch paste and the making of a Japanese-paper hinge.
WHEAT-OR RICE-STARCH PASTE
1 level teaspoon deglutinated rice or wheat flour.
1/8 cup distilled water, at room temperature.
1. Mix enough distilled water with the flour to form a mixture that has the consistency of heavy cream.
2. Boil the remaining water and add it to the mixture, stirring constantly.
Heat the mixture, in the top of a double boiler, stirring constantly until the mixture clears and thickens.
3. Tear up rice paper made of pure kozo fiber into the shape of small rectangles (the size depends on the weight of the artwork and your level of experience).
4. After the paste has cleared, thickened, and cooled, apply the paste in a thin coat to the hinge. Allow the adhesive to penetrate the hinge and dry out slightly. At this point it may be attached to the artwork, mat, or backing with the aid of a brush or a piece of card stock.
5. Immediately after application, apply pressure or a weight protected by a slip sheet until dry, usually between 30 and 40 minutes.
The illustration above right shows the wrong way to attach artwork to the mat or backing. This procedure will trap the artwork, and will eventually force the artwork to develop ripples and buckles. The illustration below right shows the right way to attach artwork. The figure on the left shows how to attach it to the mat and the other shows the hinges hidden with the artwork floating on the backing. There are two types of hinges. One is the folded hinge and the other is the pendulum hinge. The illustration on below shows both types. The folded hinge has the advantage of allowing the artwork to be lifted more easily to inspect the back. However, folded hinges have the disadvantage of holding the artwork rigidly at the point of attachment. This can result in a small but noticeable ripple between the two hinges. I prefer the pendulum hinge.
Although this hinge may make it more difficult to inspect the back of the artwork (in any case, this is rarely necessary), it does allow the artwork to hang with less restriction. I feel the pendulum hinge results in a more lasting, natural appearance.
Whatever material you choose for your hinges, the hinges should be ½- to ¾- inch wide and in the shape of a T. This T shape, or pendulum hinge, allows the artwork to breath.
The new, archival, pressure-sensitive tapes have the great advantage of easy application. Since it is a dry transfer, requiring no water for application, there is no risk of bumps or ripples showing on the front side of the artwork. The disadvantage is that most of these tapes are not as easily water-reversible as the manufacturers would have you believe. The tapes produced under the name Filmoplast become less reversible as they age, and sometimes require the assist of alcohol for removal. At this time I feel that this is not a serious draw back. Filmoplast comes in three weights. Filmoplast P is the lightest weight, and is intended for document repair and the lightest of hinging jobs. It should be
lightly burnished after application. Its adhesive strength improves a few days after application to allow you to correct any errors in application. Filmoplast P-90 is the medium weight of these tapes and the most commonly used. It should also be burnished lightly after application even though this tape has a much higher tactile strength. (In other words, it is stickier.) Filmoplast SH or SHIRTING is the heaviest. It is composed of a linen carrier and should be used only when you do not wish the tape to tear or break free. This tape should also be burnished to activate it.
A product similar to Filmoplast P is made under the name Archival Aids Document Repair Tape by Ademco Products in England. This product has a high tactile strength (much stickier ftom the outset), and is alcohol-reversible. It is thin and translucent in appearance. Because of its light weight, its tendency to become invisible, and its high tactile strength, it works well with delicate pieces such as artwork on thin rice papers. You should be cautioned, however, that because of the high tactile strength, repositioning is difficult without dissolving the adhesive with alcohol.
Lineco Inc. has recently introduced several new products for archival framing. Among them are an acid-free gummed linen tape, a self-adhesive (all their self adhesive products are based on an inert acrylic adhesive) linen cloth tape, a pressure-sensitive frame-sealing tape, a gummed sealing tape, a self-adhesive mounting/hinging tissue, and archival mounting corners. All of these products look promising and will, it is hoped, deserve and win acceptance.
The illustrations below show two methods of attaching paper artwork to a mat with backing.
The illustration on the left shows the artwork hinged to the backing with the mat folding over the artwork. It is more difficult to keep the mat registered over the artwork using this style, but it is safer if the matted artwork will be handled a great deal. The illustration on the right shows the artwork attached to the mat itself. This method allows precise registration of the artwork, but more care must be taken. Both styles have the backing taped to the mat with a linen tape (this is more commonly done when a piece of artwork is matted but not framed).
The illustration below shows a suggested attachment of a Cibachrome photographic print to a backing before the mat is placed over it.
Cibachromes are notorious for their ability to expand and contract with the slightest change in temperature and humidity. The one hinge with four comer envelopes has given the best results of any method I have used so far. It works especially well on large prints. Lineco Inc. produces an archival mounting corner made from strips of Mylar® that have been prescored for folding. The ends have a nonyellowing, pressure-sensitive adhesive, which fixes the hinge to the backing board.
temperature is used to liquify the tissue. Depending on the type of tissue used, the bonding occurs in the press or after removal.
Dry mounting is primarily used to mount photographs, posters, and any art work that is water-sensitive. This system of mounting flattens the artwork to give a clean look. It is easier, faster, and more versatile than wet mounting. The disadvantages of dry mounting are that it is not reversible in some cases and not easily reversible in other cases. If it is reversible, it is not reversible in water. The high temperatures often attained in dry mounting may cause bubbling and may prematurely age photographs as well as scorch fabrics. Dry mounting is not generally considered an archival method of mounting. (Photographs dry mounted to museum board are considered an exception to the rule by some conservators of photography collections.)
Dry mounting is a rapidly changing field. There are·continual improvements and nothing should be taken for granted. The current leading supplier to the framing industry is Seal Inc. The type of products it offers and the evolution of its products provide us with a ground for comparison. The use of its product names in the following discussion is for convenience and is not a product endorsement.
Fotoflat is a removable, thermoplastic adhesive tissue, which was developed more than thirty-five years ago. It consists of a piece of thin tissue paper, which is used as a carrier for the adhesive which has been sprayed on both sides. The adhesive melts at 180°F to 225°F (82° to 107°C) and has the advantage of not scorching and providing ease of removal with low heat. It bonds as it cools, at because of the high temperatures needed for the mounting process.
MT5 is a nonreversable (cannot be removed) adhesive tissue used for permanent mounting. The bond is activated between 225°F and 275°F (107°C and 135°C) and must be cooled underpressure. This tissue overcomes the problem of accidental separation in exposure to heat. It may, however, injure the artwork because the high tempratures needed for the mounting process.
ColorMount was developed to work with resin-coated photography papers that came on the market in the 1970s. This tissue must be used within a narrow temperature range, 195°F to 205°F (91°C to 96°C). If the temperature rises to 212°F (100°C) the moisture in the photograph will begin to boil and the resin coating will prevent its evaporation, thus creating blisters and bubbles. Tempera ture-indicator strips can help check the temperature settings.
Fusion 4000 is a newly developed thermoplastic without a tissue carrier. It is designed to resolve the problems inherent in the other products, which it does, but it also has some working difficulties of its own. The adhesive tends to be a bit runny in the press when it melts. This means that the artwork could shift position slightly, and/or some of the adhesive could be transferred to the face of the artwork if the instructions for use of cover sheets are not followed precisely. Bonding takes place while cooling under pressure.
To prevent bubbling in the use of any of the products mentioned, it has been suggested that the mounting board and artwork be predried in the dry mount press for best results.
The attempt by 3M to deal with the multitude of problems presented by dry mounting has resulted in a product it calls ProMount. This product was intro duced in 1979 for general-purpose mounting and for the mounting of resin coated photographs and Cibachromes. The manufacturer makes many claims: that it may be used on a large variety of surfaces; that no hot tacking iron is needed; that predrying is not necessary; that the adhesive is pH neutral; that removal can be accomplished by reheating; that cooling weights and pretrimming are not needed; and, best of all, that there is a five-minute "open time" to reposition the artwork before cooling. It sounds marvelous, and I hope time will confirm all these claims.
Products such as these require the reading of all technical literature and instructions on handling. Unfortunately, most visual artists rarely do this before proceeding. Materials like these do not lend themselves to impulsive creativity. Small errors will probably end in large disasters.
Vacuum Mounting utilizes an adhesive in combination with pressure to mount and flatten the artwork. The adhesive is usually applied to the back of the art work, which is then placed on the mounting board and both are put into a vacuum mount press. The vacuum mount press removes the air to create a vac uum, which in turn presses the mounting board up against the top glass cover with tremendous pressure, flattening the artwork and forcing the adhesive into the two surfaces. This creates a strong bond. There are a number of special advantages to this system. Heat, for example, which might accelerate the aging process, is not used. In addition this system can be used for wet as well as dry mounting with a spray, not with tissue.
In wet mounting, blotter papers are used in the vacuum mounting press to keep the work flat and to accelerate the drying time. The vacuum forces some of the moisture into the blotter paper covering the artwork in the press, and, if the blotters are changed frequently, the drying time is greatly decreased. This is important because if the mounted artwork takes too long to dry, mold may set in and damage the artwork. A wet mount in the vacuum mount press is usually reserved for jobs that require a water-reversible archival mounting.
There are a few companies that make vacuum mount sprays. 3M offers a spray, which is currently the brand of choice. A vacuum mount spray is designed to allow you "open time" of two to eight minutes to reposition the artwork for placement. This means that after the back of the art has been sprayed there are approximately two to three minutes of waiting time until the tack is reduced so that the surface is sticky, but will not bond firmly without pressure. The next two to eight minutes may be used to position the artwork. This unique feature allows precision mounting, and I have used it with a number of contem porary artists to creat artworks that could not have been created in any other way. After ten minutes from first spraying you must place the artwork in the press for permanent bonding. The 3M Vacumount Spray Adhesive is pH 6.8 (which is essentially pH neutral), holds up well under accelerated aging tests, and is only reversible in organic solvents, not in water. It is important to note, however, that the use of sprays such as these require the use of personal protective equipment and proper ventilation.
Vacuum mount presses are available in sizes up to 48" X84", but the most common are those that will handle up to 40" X60" boards. The system allows for the use of almost any type of mounting board, even sealed wood up to ¾-inch thick, but, as with any product such as this, the technical specification and limitation must be read first and followed accurately and completely.
Wet Mounting involves the use of a water-based adhesive to bond the artwork to the mounting board. Although this is the least expensive method of mounting, requiring minimal investment, it is the most difficult to master. The moisture in the paste that is used can also affect artwork in such unpredictable ways as temporarily changing the size, shape, and character of the paper or board to be mounted. It can permanently affect watercolors, inks, dyes, and the sizing in the paper or board, and will definitely ruin artwork done with charcoal and/or pastel. Sometimes, however, wet mounting is the only system that will work for a particular job, such as in the classical form of water-reversible archival mounting.
A brief description of the technique involved will give you a perspective on this kind of mounting. One of the greatest difficulties is in learning what consistency of paste is most workable for you and will give you the best possible results. Some people like the paste thick so it can be rubbed in with the ball of the hand. Others like the paste thinner so that it can be spread with a scrap of board, and still others like it so thin that it can be brushed on. One thing to remember is that a strong bond can be accomplished with very little paste, if it is applied correctly. I recommend that you first try thinning the paste to a consis tency that is pourable, like a thick maple syrup.
When you have the desired consistency of paste, it may then be applied either to the board or to the back of the artwork. Some artwork that has buckled or is wrinkled may have to be softened by dampening just before it is mounted. Dampening with an airbrush and water or an atomizer and water will allow the paper to return somewhat to its original flat shape. After you have applied the paste, the artwork should be laid over the mount with the center touching first and the sides held in your hands gently released. Cover the artwork with a sheet of Kraft paper and flatten it out in a '·sunburst" pattern, working from the center outward. If the paper is thin, hard, and absorbent, and has not been predam pened, you may introduce new wrinkles at this point in mounting. This is where experience counts the most. The mounted artwork has to be covered with a blotting paper and then weighted down. A thick sheet of glass is usually used for the weight. The mounted artwork should be allowed to dry in this manner (changing the blotter paper several times) over a forty-eight-hour period.
Most wet mountings require countermounting. A countermount involves mounting a piece of paper similar in weight (most people use a 40 to 50 lb. Kraft paper) to the opposite side of the mounted piece. This will reduce the tendency of the mounted piece to warp by the shrinkage of the artwork upon drying.
Spray Mounting, which involves the use of spray adhesives, is not considered a professional form of mounting, nor is it considered archival. However, it can be effective if used, with caution, on a small scale for mock-ups, models, small photographs, and collages where the convenience outweighs the disadvantages. The problem is that when a spray is used, the adhesive tends to collect on the topmost fibers of the surface. Even when the artwork is pressed out by hand during the mounting procedure, the adhesive still does not penetrate as fully as it will with other mounting methods.
Consequently, the mounting is taking place between the top fibers of one surface and the top fibers of the other. As the temperature and humidity change and the artwork and the backing expand and contract at different rates, the artwork may pull away and bubble. Beyond a certain size of artwork, the expansion and contraction would be so strong that, even if the spray were used correctly, lifting and bubbling would inevitably occur. For this reason, many sprays cannot be used with artwork above a certain size. Technical information such as this is usually printed on the spray can. Read the instructions for the brand you are using and follow them completely.
There are many adhesives that may be used in the construction of a piece of artwork, including methylcellulose, epoxy, PVA, and acrylic polymers. The adhesives discussed here are generally accepted as safe and effective for general use in picture framing.
Water-Based Adhesives. There are many water-based adhesives available for the purpose of mounting paper, paper products, canvas, and fabrics with a natu ral fiber content of 50 percent or more. Animal glues, PVA (polyvinyl acetate, wheat or rice paste, and methyl cellulose are among the pastes most commonly used by framers.
Animal Glues are generally made from the gelatinous tissues found in the bones, skins, and intestines. Animal glues are used because they are inexpensive, have a longer shelf life than vegetable adhesives, and are usually comparatively low in water content (less moisture is advantageous because it means the paper tends to buckle less during application). Animal glues are not, how ever, considered archival because they tend to yellow, acidify, and crystallize (become brittle) with age. Increased awareness of these drawbacks has greatly diminished the use of animal glues.
PVA Emulsions, commonly known as "white glues," were the precursor to the development of acrylic polymer emulsions and paints. Their advantages include low cost, a long shelf life of several years, and easy application. Some undesirable characteristics of PVA adhesives are that they are not water-soluble when fully dry, and they contain a larger percentage of water than animal glues. This high degree of moisture contributes to the buckling and wrinkling of paper during mounting. Alcohol can be used to re-dissolve the adhesive within the first few years of application. The lack of water reversibility prevents this adhesive from being classed as archival.
Wheat Paste and Rice Paste are starch pastes, which have to be made fresh each time before use. (A recipe is given on page 288.) These vegetable pastes are water-soluble, archival, and therefore safe for hinging, mounting, and repair ing paper or paper products used in making fine art. Vegetable pastes tend to be more hydroscopic than animal pastes, which means that vegetable pastes tend to retain more water per weight of paste, and when the paste is used it will tend to impart that moisture .to the paper or board being mounted. This may lead to more buckling and difficulty in mounting. Vegetable pastes form a stronger bond with paper products than animal pastes. Some control can be exercised over the moisture by using less paste, thereby reducing the tendency of the paper to buckle. Beware of ready-made wheat or rice pastes, which have a very short shelf life and may become acidic.
Methylcellulose is like a vegetable paste with the vegetable part completely removed. It is pure adhesive. It mixes easily with cold water and the resulting substance looks very much like colorless Jello. It is nonstaining, water reversible, pH neutral, and completely archival. The only drawback is that methylcellulose is very hydroscopic, and this high content of water can easily be imparted to the paper or board used, causing wrinkling and buckling. Most people use far too much of this adhesive during application. Since this material is nothing but adhesive and water, very little is needed. Methylcellulose is new on the market, and although it makes an ideal paste for archival mounting, some experimentation and practice is needed to learn how to keep problems of moisture to a minimum.
Lineco Inc. and Seal Inc. have recently offered waterborne, water-reversible, neutral pH adhesives that are ready to use without special preparations, and that they claim meet archival standards. Lineco's adhesive is made of a modified dextrine base, which is reactivated when wet. If these products gain acceptance they will certainly ease the difficulty of wet mounting.
Spray Adhesives. Always read the instructions on the container of any spray adhesive before use. This cannot be emphasized too strongly.
There are many factors that can affect the quality of the bonding when using a spray adhesive. The most important ones are texture, moisture, temperature, and the flatness of the object(s) to be mounted. Texture can be a problem if insufficient adhesive is used and inadequate pressure is applied. The "valleys" as well as the "hills" in the texture of the surface have to be part of the bonding process if the mounted object is to be held permanently.
The moisture content and temperature of the objects to be mounted together have to be the same or they may expand or contract differently from one another and cause adhesive failure. This simple problem can be avoided by storing the objects to be mounted in the same location for several hours before and after mounting. If you have to soften the object to be mounted by humidifying it, then humidify the mount, too.
Removal of items mounted with either of these sprays may be accomplished with the use of heat or a solvent such as rubber-cement thinner or lighter fluid. You may also find an extra pair of hands necessary to accomplish the recom mended techniques. 3M recommends that you lay the mounted object down on a table and use a commercial heat gun or a hair dryer to heat one of the corners. The heat source should be 4 inches or more away from the object. A thin spatula or knife can be worked carefully under the corner to begin the process of lifting off the mounted piece. Continue to lift the corner while heating the point of removal. The object should be lifted off during this heating process, not peeled off.
As for the solvent method of removal, 3M recommends that you stand the mounted object in a vertical position and drip some solvent onto the corner. After it has soaked into the corner, begin to lift off the object with a thin spatula or knife. Continue to drip solvent into the point of removal and lift at the same time. After removal, you may wish to wash off all traces of the adhesive with the solvent.
Although these methods are effective, it is difficult to accomplish them with out affecting the object. However, this would be true of virtually any removal process; the challenge is to minimize that.
These aerosol spray adhesives and solvents present a serious health hazard if used without proper precautions.
As for the solvent method of removal, 3M recommends that you stand the mounted object in a vertical position and drip some solvent onto the corner. After it has soaked into the corner, begin to lift off the object with a thin spatula or knife. Continue to drip solvent into the point of removal and lift at the same time. After removal, you may wish to wash off all traces of the adhesive with the solvent.
Although these methods are effective, it is difficult to accomplish them with out affecting the object. However, this would be true of virtually any removal process; the challenge is to minimize that. These aerosol spray adhesives and solvents present a serious health hazard if used without proper precautions.
GLASS AND PLASTIC
Glazing means to fit with glass or glasslike material. There are several types of glass and plastic available to glaze pictures, and the following discusses these materials.
Glass. There are two weights of glass commonly used in picture framing, picture glass and single-strength glass. Picture glass is lighter and not as strong as single strength. Picture glass was popular some years ago because it is thinner and therefore occupies less space; the popular mouldings of that time were not as deep and space was a consideration. The lightweight characteristic of picture glass had an advantage in larger frames, but at a certain point, its reduced strength became more important than the weight factor. Today, quality picture glass is expensive and hard to find. All of this has discouraged its use.
Single-strength glass comes in two grades, A and B. B is the same as A except that it is not inspected before it is packed. Single-strength is the glass most commonly used today. Double-strength glass, which is approximate!y 20 percent stronger, is rarely used even for larger pictures because of its heavy weight and slight, but noticeable, green tint. Glass transmits about 80 to 83 percent of light, and the greenish tint varies in degree depending on the thick ness of the glass.
Nonglare glass, which is glass whose surface has been etched to diffuse the reflection, is most effective when the artwork is placed up against the glass (which violates one of the basic rules about paper artwork). The greater the space between the artwork and the nonglare glass, the fuzzier the image becomes. In most cases the space created by a single mat will not make the image sufficiently fuzzy to disturb most people, and there are circumstances where reflection is a serious problem. In these situations nonglare glass may be considered. I prefer a crystal clear image with reflection to paying more and getting a fuzzy image with a diffused reflection.
A new product called Denglas, made by Denton Vacuum, Inc., which has a metalized coating, would be the ideal solution, except for its extremely high price tag. Regular glass has an approximately 8 percent reflection. Denglas has a I percent reflection and can also absorb some ultraviolet light. Each sheet of glass is apparently made with a coating of metallic particles applied in a vacuum chamber and it is this coating of the surface of the glass that produces this effect. Denglas was originally developed for scientific apparatus. Its effec tiveness is particularly startling when used with very dark images. Because the cost of using this glass could double the price of framing, it is primarily reserved for use with very valuable artwork, or where light reflection is an overwhelming problem.
Plastics. There are three types of plastic sheeting used most frequently in the picture framing industry: polystyrene, polycarbonate, and acrylic. (Plexiglas is the trademark of Rohm & Haas for clear acrylic sheeting.) Polystyrene is a rela tively soft plastic used in the making of such mass-produced moulded plastic products as plastic cups, plastic toys, and inexpensive box frames. This product is not ideal for valuable artwork because it yellows as it ages. It is also more brittle than polycarbonate and acrylic.
Polycarbonate, because it is virtually unbreakable, is used in protecting valuable artifacts or artworks that are on public display. It is rarely used in conventional framing because of the high cost and because it must be cut on a table saw using a special blade manufactured for this purpose. A ventilation system is necessary to protect against toxic vapors that may arise in the heat produced during cutting. In general, using polycarbonate in conventional framing is con sidered overkill.
Clear acrylic (polymethyl methacrylate) sheets in 1/8 inch, and 3/16 inches for works over 40" x 60", are the most common replacement for glass in picture framing when the possibility of breakage outweighs other concerns. The advantages of acrylic are that it is lighter weight than glass, it can be scored and broken to size without expensive equipment, it is far less breakable in a picture frame than glass, and it is clearer and transmits more light (90 percent) than glass. The disadvantage is that acrylic cannot be used with chalk, charcoal, or pastel artwork due to the static charge it develops, which can lift a significant amount of material off the surface of the artwork and adhere it to the surface of the acrylic sheet. Exposure to strong ultraviolet light can yellow acrylic, but this is of more serious concern to institutions and industries that are using such special lighting as mercury vapor lamps. Acrylic also scratches easily and is a fire hazard. When plastics such as these are heated or burned without sufficient oxy gen (which would be the case in most ordinary room fires), they give off large quantities of toxic and suffocating vapors.
Regular acrylic sheeting, like glass, provides little protection of artwork from the effects of ultraviolet light, one of the major contributors to the fading or darkening of artists colors. Virtually all artists' colors, in varying degrees, are sensitive to the visual light spectrum and to the invisible ultraviolet spectrum. Ultraviolet light is of greater concern because of its higher energy, which, besides fading or darkening a color, can produce chemical changes that include making artwork more brittle and structurally weaker. These changes can also occur from the higher energy levels of the visible light spectrum such as violet and blue, but not to the same degree as ultraviolet. The major sources of ultra violet light are direct sunlight and fluorescent light.
In most cases, it is not difficult to avoid exposure to direct or even a large amount of reflected sunlight. It is usually just a matter of placement. Exposure to ultraviolet light from fluorescent light fixtures, which is a common form of lighting in institutions, is a problem. To solve this problem, especially for deal ing with artwork or artifacts that are particularly sensitive, ultraviolet-filtering clear acrylics were developed. (The only form of acrylic that will filter both ultraviolet light and visible light comes only in black. So, as long as you wish to see your artwork you will have to accept the effects of most of the visible light spectrum.)
There are two basic types of clear acrylic that will filter ultraviolet light. One type can filter all ultraviolet light as well as part of the visible violet light range. (Visible violet light is part of the visible light spectrum, which can also have a considerable effect.) This type of acrylic can reduce the damage caused by ultra violet light by 95 percent; nevertheless, it has a faint, somewhat distracting, visible yellow tint. The other type of acrylic has no effect on the visible light range and will protect against most, but not all, the ultraviolet light spectrum, thus reducing possible damage from this part of the spectrum by 90 percent. Since ultraviolet light is invisible, so is the protection and therefore there is no objectionable yellow tint.
Ultraviolet filtering acrylic is currently used only in special situations where exposure to this type of light will cause severe or long-term damage. The high cost of this material prevents its indiscriminate use. Rohm & Haas produces the two types of products for filtering ultraviolet light, Plexiglas UF-1, which has the yellow tint and provides the most protection, and Plexiglas UF-3, which provides a reasonable amount of protection without the yellow tint.
Mouldings, which may be either wood or metal, are ornamental contours given to an object. Mouldings for framing do more than decorate-they hold the glazing, picture, and backing together so that the artwork can be properly protected and displayed.
Wood Mouldings have height, width, a back, lip, and rabbet. The illustration below shows what these terms refer to. In the recent past, basswood was one of the most popular woods used in modern framing. But this wood has continued to increase in cost, limiting its use to finer-quality decorative mouldings.
From the linden tree, basswood is a soft wood ranging from white to cream in color, and of the many woods used in framing, it has the least apparent grain. Basswood resists splitting, does not warp easily, and can be sanded to a fine finish. It also accepts gold leaf well. Because of its softness, however, basswood is not considered to be the best choice for gallery-style framing. (Gallery-style framing is that which can be handled a great deal without being damaged easily.) Poplar is used as a substitute for basswood because of its similarities, but it tends to warp more.
Kiln-dried pine (if pine is not dried properly, its natural resins can leak) is used mostly in less expensive mouldings because of its abundance, although its large resin canals make working with it more difficult. Resin canals sometimes deflect nails, which can result in splitting and the nail can also end up in the wrong place. These canals also make it difficult for even sanding and finishing. Fir is often used as a substitute for pine because of the similarity, but it has a wider grain, which adds to the splitting problem during the nailing of the frame. Although most of these woods are not as soft as basswood, they are soft enough to be of concern if they are to be handled in a gallery situation. Their great advantage is that because of their softness they are more easily worked
without expensive equipment. Flaws in cutting the miter are easily covered by compressing the two corners during their joining.
Hardwoods do not compress and small flaws in the cutting of hardwoods will not go away. There are many beautiful hardwoods, including padouk, cherry, walnut, maple, and mahogany, that are used as mouldings for picture framing because of their unique textures and colors. The woods discussed here are those most commonly used for picture framing.
Ash is a hardwood that is easier to work with than most of the woods in this category. Its color ranges from a cool gray-white to a brownish-red. In the lighter tones the grain looks like a darker version of poplar and in the darker tones, the grain resembles that of oak. Ash does not split easily when nailed or otherwise worked with, which is why many people prefer to use this wood whenever possible.
Oak has three color varieties consisting of white, red, and brown. The characteristic coarse grain and pores makes oak one of the most easily recognized woods. It is more popular for decorative artwork than for contemporary artwork because of its strong appearance. It is hard and heavy, has a tendency to split, and is one of the most acidic of woods
Ramin is an evenly grained, light, cream-colored wood. This wood, a recent introduction to the framing industry from southeast Asia, is lighter in weight than most, and does not split as easily as oak. Ramin does not stain well, but can be easily sanded and finished. Because of its soft neutral look, this wood is rapidly becoming popular.
Working with raw woods without expensive equipment is within reason for an artist with some basic knowledge of woodworking. Most artists who get a taste of do-it-yourself picture framing, however, usually proceed to go out and find a good professional framer to do it for them. If you are one of the dedicated few who wish to work with raw woods as opposed to finished mouldings, you will have to seal them to help protect against shrinkage, splitting, dirt, and moisture. After mechanical abuse, shrinkage is the next major cause for corners coming apart. Unsealed wood can shrink as much as 5 percent along its length. Raw wood can easily be sealed with hot paste wax, liquid wax, woodworking oils, or any commercial product made for this purpose. As for gesso, lacquer, gold leaf, staining, and painting of woods for picture framing, unless you wish to have a second career as a picture framer, I recommend that you purchase what you want from a picture framer. There are many picture framers who will sell you mould ing by the length, or moulding cut and mitered, or moulding cut, mitered, and joined, so that you may assemble the rest yourself.
Joining mouldings to make a frame is most easily accomplished by gluing and nailing. It is a common misunderstanding that the nails hold the corners together. The nails only assist in houlding the corners together while the glue dries. It is the glue that will ultimately hold the corners together over time, so using large nails or many nails is not necessary and can even weaken the wood. I recommend yellow carpenter's glue, which is an aliphatic resin. This glue is water-soluble, sets quickly, and is a strong wood glue. Water solubility makes it.
easy to clean up excess glue that might affect the wood's ability to accept stains or finishing oils. Aliphatic resins are more brittle than white glues, which are composed of polyvinyl acetate. I feel that with the exception of very large frames, the brittleness of an aliphatic resin is an advantage because it allows a frame to be taken apart for repairs without being destroyed.
To avoid splitting and nails working their way to the surface of the moulding, hoks should be drilled for the nails before hammering. I recommend, again with the exception of large frames, that you place the nails into the comer in one direction. This will allow you to take the frame apart for repairs. Use the small est and shortest nails that you can work with and still get the job done.
Metal Mouldings are much easier for an amateur framer to work with. They can be purchased precut or cut to order and can be assembled with simple hand tools. If you follow the rules of framing that I have outlined, you can end up with professional results. The major difference between a wood and a metal frame is that you cannot have an airtight seal with a metal frame. This can be a serious consideration if the artwork is sensitive to moisture or air pollutants. In most cases, artwork that is framed with metal, if not placed in a bathroom, on a boat, or in a smoked-filled room at a political convention, should not be greatly affected.
Building a setback into a wood frame can be difficult and, if you are paying to have it done, expensive. There are metal mouldings that are made with a set back built into them. (See the illustration above.) This allows for a relatively inexpensive form of conservation framing where the artwork could be float mounted to museum board and kept away from the glass.
Aesthetics in Framing
The AESTHETICS of framing is a subjective area, but the following guidelines will give you something to follow.
1. Look first, then see. To look first at the artwork and at possible selections for framing means to perceive it without preconception and storylines. To see is to grasp relationships and ideas. If you look and then see, you have perceived what is actually there and then related it to your ideas. If you see first and then look, you often perceive only your ideas and frame them, not the picture.
2. Frame to the picture first. Although most people change their decor several times during a lifetime, few reframe a picture to match those changes. If you frame to the picture, you will always have at least one match.
3. Beware of framing that is too interesting or too beautiful. It is very easy to select framing that overwhelms the picture. If you find youself looking more at the frame than the picture, your selection is out of balance.
4. Remember the original purpose of picture framing, which is to protect the artwork. Avoid creative framing at the expense of common sense. Stay within the rules of good framing.
5. The width of a mat should be clearly larger than the width of the moulding.
6. Double mats and fabric mats, when used conservatively, can create a focal point and a sense of depth. This is particularly true with photographs.
7. If you wish to bring out a particular color, choose a mat of a complementary color, not the same color.
8. A little more space should be given at the bottom of a mat. Artwork such as prints that are signed at the bottom are not usually given this extra space because of the extra space created by the signature.
9. A mat should be the same or one shade darker in appearance than the brightest part of the artwork. Exceptions to this rule may be made if the mat is made extra large (3 ½ inches to 6 inches).
10. Artwork that has a rough or deckled edge should be considered for float mounting to show the edge; artwork with a cut edge should considered for over matting. A proper choice will bring a piece of artwork to life.
BELOW ARE several guidelines for safe picture hanging.
1. Do not hang a picture over a working fireplace. The exposure of artwork to the heat, smoke, and ash of a fireplace can result in serious damage. For artwork that is framed under glass and sealed from the atmosphere, you need only worry about the heat, which causes rapid acceleration of the aging process. Unprotected artwork will collect soot and will also be subject to the alkali of ash and the acids that result from the sulfur dioxide and hydrogen sulfide gases that are produced by the fire.
2. Do not hang a picture over a heater or under an air conditioner. Rapid changes in temperature, which are often accompanied by rapid changes in humidity, will cause premature aging.
3. Do not hang artwork on walls that are prone to dampness or mildew. Out side walls of a house are more prone to dampness and to the development of mildew. When a piece of artwork is placed over a damp wall, the combination of dampness and darkness becomes a fertile ground for mold and mildew. Mildew is like cancer to artwork; once the artwork has it, it is difficult to get rid of it permanently.
4. Do not hang artwork where it will be exposed to direct sunlight. Avoid expo sure to fluorescent lighting and strong indirect lighting. Light is the major cause of fading in artwork. Ultraviolet light, which is most concentrated in sunlight and fluorescent light, causes not only fading but unpredictable photochemical changes in artwork as well.
Over the years I have come across a number of novel methods of storing artwork. One of the more noteworthy was that of a collector who stored his art collection in his wine cellar; after all, the paintings were old and valuable like the wine. Unfortunately, the artwork was not sealed in bottles like the wine, and was subject to mildew, mold, rot, insects, and rodents.
Storage of artwork involves protecting it from excessive humidity and excessive dryness, and from insects, rodents, and acids. In addition to the archival boards and papers, there are materials such as storage boxes and envelopes for Mylar encapsulation, that are specially designed for use by museums and conservators. Such materials are primarily for the storage of collections that are not, for whatever reason, to be left on exhibition. Some of these materials can also be useful to artists who wish to use such ready-made storage containers rather than make their own. These products have yet to work their way into the aver age art supply store, and it is not within the scope of this book to review these products. However, there are several mail-order companies that deal in these materials and a catalogue can be had upon request. The Light Impressions Corporation, 439 Monroe Ave., P.O. Box 940, Rochester, NY 14603, is among the more commonly known mail-order houses from which a catalogue can be had.
Below is a list of suggested remedies for the most common storage situations that the average artist and collector confronts.
1. Framed artwork and stretched artwork should be stored in racks that will allow for the circulation of air and exposure to some light to prevent the growth of fungus.
2, Unframed paper artwork should be stored in fiat file drawers that are lined with museum board and contain packets of boric acid. The flat drawers will protect against mechanical damage. The museum board will protect against any acids present in the drawers, particularly in wooden drawers. The boric acid will prevent silverfish. (The General Pest Service Company produces Dekko Silver fish Paks, which contain boric acid and are easy to use.)
3. Paper artworks may be stacked upon one another if they are separated by pH neutral slip sheets.
4. Unstretched canvas paintings may be stored rolled if they are first allowed to dry thoroughly, then rolled around a thick tube with the painted side out and the surface protected with a glassinelike paper. The painted side is placed on the outside because any cracks that might form from this type of storage will be pushed back together when the canvas is unrolled. If the painted side is rolled inside the tube, the paint film might cure in this compressed state and larger cracks may result when the painting is later unrolled.
5. Metal flat file drawers are best when insects are of primary concern, and wooden flat file drawers are best when humidity is the primary concern.