And which would be considered the least environmentally friendly? A Pyro variant?
Pyro is probably the most environmental of the lot... Gallic acid comes from oak galls - produced by oak trees to fight off parasites. Boiling thegalls gives you pyrogallol. Got an oak tree in the yard?
The other ingredients are in smaller proportion than in any other developer. Per liter: PMK D-76 Metol 0.05 2.00 Pyro/HQ 0.50 5.00 Sulfites 0.10 100.00 Borates 6.00 16.00 Though 1 liter of D-76 will develop more film than a literof PMK, it isn't anywhere in proportion to ingredient quantity.
Pyro's toxicity is really overblown. The LD50 (rat) is around 1200 mg/kg. Compare that to table salt at 3000 mg/kg. Yes it is an irritant - it is supposed to be irritating - that was the oak tree's intent when it made the stuff. Contact with skin? Try this: http://www.henriettesherbal.com/eclectic/bpc1911/acidum-pyro.html Not in current use, but still in the pharmacopoeia. Catechol? Better become a beef eater if you want to avoid it... http://www.ehow.com/about_4619323_catechol-in-bananas.html http://en.wikipedia.org/wiki/Catechol == Nicholas O. Lindan Cleveland Engineering Design, LLC Cleveland, Ohio 44121 ============================================================================================================= To unsubscribe from this list, go to www.freelists.org and logon to your account (the same e-mail address and password you set-up when you subscribed,) and unsubscribe from there.