Cyanotype formula question

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From: Loris Medici (lorism@tnn.net)
Date: 10/21/03-07:35:10 AM Z


I see that unblinkingeye site (very nice site of Ed Buffaloe - thank you
very much) refers to Dick Sullivan's Cyanotype formula. The main
difference is the addition of oxalic acid to both parts A and B plus the
addition of ammonium dichromate to part B.

1) What is the purpose of the addition of oxalic acid? I have citric
acid; can I substitute it with citric acid?

One question about citric acid; does moisture affect citric acid's
chemical properties (I have citric acid that is in form of lumps - not
powder - due to exposure to moisture)? Will moisture-affected citric
acid work the same way as powder citric acid? (I will weight say
....10-20% more due to the H2O present in the lumps)

2) What is the purpose of addition of ammonium dichromate? Can it be
substituted with half the amount potassium dichromate?

Thanks in advance,
Loris.


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