Dry Mounting is the use of a dry tissue adhesive that is activated by heat from a heat press or an iron to bond artwork or a piece of fabric to a mounting board. The tissue is placed between the object to be mounted and the board. A high temperature is used to liquefy 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 about 150°F (66°C). The disadvantage is that mounted works exposed to the heat of direct sunlight or left in a hot car could separate from the mounting board.
MT5 is a nonreversible (cannot be removed) adhesive tissue used for permanent mounting. The bonding is activated between 225°F and 275°F (107°C and 135°C) and must be cooled under pressure. This tissue overcomes the problem of accidental separation in exposure to heat. It may, however, injure the artwork because of the high temperatures 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. Temperature-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 introduced 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.
(Excerpt from ART HARDWARE: The Definitive Guide to Artists’ Materials, by Steven Saitzyk © 1987)