[pure-silver] Re: "Green" Developer
- From: "Nicholas O. Lindan" <nolindan@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Sun, 29 Nov 2009 14:31:29 -0500
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 the
galls 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 liter
of 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
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