Re: gum preservatves
I am not sure what the "correct" amount of sod benzoate per weight of (dry) gum is. I just asked the importer advice on preserving the gum mixture. I also read somewhere about "sour" gum being faster (Kuhn?) but never tried it. If I need a faster reacting mix (as when using RC photo paper as negative) I use casein instead of gum: a speed gain of approx 2 stops for me. I also use PVA (Mowiol), a mixture of mowiol with paint and pot bichromate can, even after 2 weeks storage, be used for printing without loss of speed or quality. Mowiol however prints slower than gum - approx. 2 stops slower in my set-up. I mainly use both casein and mowiol when printing with Acrylic paints.
2008/9/4, Loris Medici <firstname.lastname@example.org>:
FDA allows E211 in food unless concentration doesn't get over 0.1%. That's