Re: be careful about description of borax and other borates
Ryuji, thanks for that distinction.
Since as far as I know, I'm the only one who has mentioned borax, I should hasten to emphasize that I wasn't suggesting that people might want to use borax mixed with PVA (or gum, for that matter) as a size for gum prints! For one thing, the product is very slimey and probably wouldn't coat very nicely. For another thing, the links are weak and the product is soluble in water, which would defeat the whole purpose of a size.
If anyone is interested, it's the tetrahydroxyborate ion-- B(OH)4- that is involved in the crosslinking.
On Aug 31, 2007, at 12:55 PM, Ryuji Suzuki wrote:
Borax is sodium tetraborate. It is most commonly available in decahydrate form. The sodium salt of boric acid is called sodium metaborate. Borax, once dissolved in water, is equivalent to a equimolar mixture of boric acid and sodium metaborate dissolved in water. All these borates have mild plant toxicity and are not very desirable to discharge to the environment, especially in sensitive areas. Borates are not removed by usual water treatment, and they are not decomposed by usual bacteria. So about the only way to reduce the harm is massive dilution. (Same goes to EDTA, DTPA, NTA, etc.) -- Ryuji Suzuki http://silvergrain.org