Film putty
Film putty is the traditional term for adhesive used in film assembly. Actually, it is not about putty , as it is otherwise used for joining, but a mixture of solvents for the film with adhesive additives, such as dissolved film carrier or zapon varnish .
With the global change from flammable to safety film in the early 1950s, new recipes were also tried out for film putty. The cementing components have been omitted. Today film putty is a mixture of solvents.
The main solvent for cellulose nitrate film is isoamyl acetate as found in 1882 by John H. Stevens. The main solvent for cellulose acetate film is methylene chloride ( dichloromethane ). In addition, we know propanone , 2- butanone , dioxane , ethyl acetate and others. For many years the toxicity of the chemicals was not discussed. But even today, kidney-damaging and carcinogenic substances are still used. A film putty that is harmless in this regard has been on the market since 2000.
Film putty or film adhesive should be purchased and used in small quantities. There is no compromise when it comes to assembling valuable originals: the negative has to hold up as it passes through the copier , like undamaged film: flexible, without bubbles, without thickening. There is a fresh film and an older one, which may become horny, brittle, or chemically disintegrate. Accordingly, a film putty should be selected so that durable splices can be made. For this purpose one can use fast and slow setting products; with cold or heated glue press ; work with glue presses with fixed and elastic pressure bars.