I'm hoping to get some expert input on a tagging question specific to finding aids for photograph collections.  What would be the most appropriate tag to describe the chemical process or materials used to create a photograph?  Examples of descriptions that we would like to include are:
 
-Blue-toned Chlorobromide print
-Chlorobromide print on Opal G. paper
-C.B. toned selenite
 
The definitions of both <genreform> and <phystech> do not seem to offer a perfect match for this kind of description.
 
Additionally, a more general question for those with experience in EAD and photo collections.  Are there resources that you would recommend as EAD guides for those working primarily with photographs?
 
Thank you for any suggestions,
 
Best,
Elizabeth Russell
Visual Materials Assistant
Special Collections
University of Washington Libraries
 
MLIS Candidate
iSchool
University of Washington