From: Paul Martinez (paul_c_martinez@yahoo.com)
Date: 01/24/03-08:00:33 AM Z
I think I remember reading somewhere (book of Pyro?) that pyrogallo is/was derived from gall nuts that had been "cooked"
Monnoyer Philippe <monnoyer@imec.be> wrote:
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|Greetings!
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|Some one know what gall nuts are?
Yes. It is an "illness" for oak trees.
Gallic acid is extracted from these nuts.
In fact, Scheele first produced gallic acid from the gall-nut in 1786. Gallic acid comes from the tannic acid in the nut.
Combined with iron, the gallic and tannic acids give a black dye and is used in ink, and, for example, to tone cyanotypes.
Gallic acid is not pyrogallol tough, but close.
If you need a substitute to the gall-nut, I would suggest you use tanin or gallic acid. You can buy tanin in shops where people buy the equipment to make their own fruit wine. It's very cheap.
Gallic acid, on the other hand, will be a lot more expensive I think.
If you want to be strict and as close as possible to gall-nut, yo should defenitely use tanin (= tannic acid).
Cheers,
Philippe
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