Albumens are photographs on paper, wherein the emulsion containing silver salts is made with egg albumin. They are usually yellowed and cracked because of the tension caused by the emulsion, albumen, which is only on one side of a very thin paper. To prevent this curling they were mounted on very thick cardboards.
Top, left: Albumen with substantial loss of support. Right : After consolidating the paper and adhere it on a thick conservation board. Gaps have not been treated in order to do so on the digitized image.
Top left: Typical albumen adhered to a board. This one belongs to the Library Delmiro Caralt (Catalonia Film Archive). I’d rather not use microscopy to see the effects of cleaning… but sometimes not much more than that is possible. Right: After surface cleaning of the photographic emulsion.