Re: chemicals: dyeing mordants


Sil Horwitz (silh@iag.net)
Mon, 17 May 1999 21:34:35 -0400


At 99/05/17 04:40 PM -0400, Suzanne Izzo wrote:

> sodium carbonate (listed as both washing soda and Glauber's Salts)

Glauber's Salt is sodium sulfate, not carbonate.

Also, there is a problem with commercial sodium carbonate ("washing soda" or
just "soda") - what they normally furnish is crushed crystals, which have a
variable amount of H20 in the compound. Photographic sodium carbonate is the
monohydrate, which is stable and free flowing. You would have to analyze the
commercial compound to determine how much water is present in the powder, and
then use a formula to figure the amount needed to replace the monohydrate.

Sil Horwitz, FPSA
Technical Editor, PSA Journal
silh@iag.net
Visit http://www.psa-photo.org/
Personal page: http://www.iag.net/~silh/



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