The other day I spent time with a friend who I met at art college. She is an amazing collage artist. One of these days I'll convince her to have a blog or website but for now you have to take my word that her art is amazing.
Anyway, she introduced me to acid free Yes paste to use when creating collages. I've been using Golden Soft Gel for my collages. Yes paste leaves the hand of the collage paper pretty much as is. Matte medium leaves a film or gloss on the collage paper. Either product is good and I'll probably use both for future collages.
Here is Collage #38 which was made using stained bleeding tissue paper and Yes paste.