R: update on powdered gum

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From: Alberto Novo (alnovo@inwind.it)
Date: 04/19/03-11:18:57 AM Z


> Another thing: in PhotoAquatint Demachy says to mix your
> gum arabic up
> to 30-35%. However, in a talk he gave to the RPS in March 1898
> he counsels
> to mix the gum to a baume of 18 to 20, using 1 part gum to 2
> parts water. I
> assume this is a 50% solution, correct? Or is my scientific
> ratio knowledge
> in need of an update?

Christina,
I regret but I think so... it is about 30-35%!:
1 part + 2 parts = 3 parts; 1/3= 33.3%

What is unclear in some recipes is what a "part" is: if it is a volume,
surely 1 part of powdered gum arabic weights less than 1 part of water, so
the resulting concentration will be below 30%.

Alberto


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