This is a great trick I use for all sorts of craft stuff! I haven't had it come off anything yet, and it won't damage old paper or discolor over time. I got this from a lady who has kept "town scrapbooks" for a great many years, asnd even the 50 year old books look like they were put together yesterday. I haven't tried it on glass yet, but it's worth a try.
Mix 2 tablespoons of cornstarch with 1 cup ice cold water. Bring it to a boil, stirring constantly, until it thickens and turns almost completely clear. Best stored in the fridge.