Quote Originally Posted by holmburgers View Post
Methyl cellulose, aka carboxy methyl cellulose or CMC gum is a commonplace ingredient for ceramicists and is used in glazes. It'd be fantastic if DAS and CMC gum could potentially used in a gum-bichromate like process. I'm curious to know more about Kees' synthetic colloid as well.

Also, does anyone know if PVA refers to polyvinyl acetate or polyvinyl alcohol?? I would assume PV-alcohol (Elmer's glue), but I'd like to be sure.

Hi, I could not resist to do some quick tests with DAS and methyl cellulose. A fairly thick 2,5% methylcellulose solution was 1:1 mixed with standard 3% DAS. Mixed in some lampblack watercolorpigment. This mix was applied on a gelatin sized and hardened watercolor paper. It was difficult to apply an even coating, much more difficult than with gum. After some testing I found out that a 15 sec (!) exposure under a bank of UV TL was sufficient. The methylcellulose shows a very heavy stain after exposure. The print can not be developed in cold water, nothing happens there. I found out that a rather warm bath or even a stream of warm water (▒40░C) like with carbon worked well. So, yes it works!

When speaking of PVA I allways refer to PolyVinyl Alcohol, available under various brand names. I'm using Mowiol. Polyvinylacetate (PVAc) is very different and not suitable for pigment/collo´d printing because when dry, as far as I know, it is not water soluble anymore. It can be used as a sizing for paper. PVA works with DAS but not that good in my testing. I have found very good hardening and extemely high sensitivity with some polyvinylpyrolidones (PVP).

Kees