From: Richard Knoppow (dickburk@ix.netcom.com)
Date: 05/28/00-06:30:11 PM Z
At 07:17 AM 05/29/2000 -0400, you wrote:
>In a previous message I mentioned my experience substituting
>potassium carbonate for sodium carbonate in several developer at same
>weight and experienced with no change in characteristics of the
>developer.
>
>I have since consulted Haist. He writes that the result of much
>investigation shows that in many developing formulas the two
>carbonates can be substituted at equal weight freely, but that in
>some formulas not! The research in question was all with M-Q
>formulas. The definitive answer is ??????
>
>Sandy King
>
>
Since you are lucky enough to have a copy of Haist (he said with his
tongue hanging out) does he say anything else, like giving a hint about
what sort of formulas the Potassium form is not good with? Since Sodium
Carbonate shows up in three forms in formulas it would be useful to know to
which he is refering. Some very old formulas specify cryataline carbonate,
most later ones specify either anhydrous or monohydrated.
Kodak, in their 1930's book on motion picture laboratory technique
recommends the potassium type _because_ it is delequescent and if spilled
will stick to whatever it falls on and not blow around. The delequescense
is a problem with the crystaline form of the sodium variety. The advantage
of monohydrated sodium carbonate is that is is very stable. Potassium
carbonate evidently does not store well.
---- Richard Knoppow Los Angeles,Ca. dickburk@ix.netcom.com
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