Topics in Photographic Preservation 1986, Volume 1, Article 1 (pp. 1)
Occasionally it has been noticed that during the course of treatment a gelatin print that has a tendency to curl will have the degree of curl increase in severity as a result of aqueous treatments. This curling will also become more pronounced at the edges of tears, or at breaks in the emulsion, causing the breaks to become larger and more pronounced (“tenting”) and aggravating the separation of the emulsion layers. Routine flattening attempts do not help the curl, and in fact, appear to make the problem worse.
Various suggestions were made during the meeting in Charleston, including
Splitting of the photograph before mending, then remounting the layers to each other.
Consolidation of the layers with non-aqueous adhesives, or emulsions.
Consolidation of the edges of the breaks and tears with gelatin before aqueous treatment, which does seem to help.
Since the meeting in Charleston, I have found a form of controlled drying which has proven somewhat successful in minimizing the tendency to curl in gelatin prints during aqueous treatments. By allowing evaporation to occur only from the emulsion side, a gelatin print will tend to dry flat.
First lightly spray the emulsion side and, when it relaxes, spray the reverse more heavily. Place the back of the photograph against smooth polyester web, over heavy mylar. Cover the emulsion side with polyester web and several layers of dry blotter. Moderate weight is necessary, and the blotters should be changed frequently until the photograph is dry. Tears and breaks should be mended and consolidated before final flattening, but the object should be dried in this way after every aqueous treatment.