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Name: Al S.
Status: other
Age: 20s
Location: N/A
Country: N/A
Date: 9/12/2004


Question:
I am currently reviewing old recipes of ink making specifically iron gall ink. I have found a recipe calling for the use of iron dissolved in acetic acid and not the regular ferrous sulfate. It claims it to be more permanent. I have myself experimented with both inks and found the first one to be very water resistant whereas the latter much less so. Can anyone please explain this? and also does this have any bearing on the long term permanence of the ink?


Replies:
The acetate salt of Fe(+2) evolves acetic acid (vinegar) when it dries (especially if it is heated). This results in the formation of (probably) iron oxides and/or iron salts of organic acids present in the paper or canvas. Hence is forms a "faster" color (to use the jargon) than the sulfate salt which remains water soluble because the sulfuric acid is not volatile and forms a permanently soluble residue.

Vince Calder



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