On Fri, 17 Dec 2004 16:06:12 -0400, "Bob Kiss" <bobkiss@caribsurf.com>
said:
> DEAR RYUJI,
> I STILL haven't unpacked my books after moving homes/darkrooms. Do most
> standard photo formulas call for Sodium Carbonate monohydrate or for
> anhydrous Sodium Carbonate?
Sodium carbonate monohydrate is much more often specified in
photographic formulae.
Anhydrous version tends to absorb moisture from air and it is more
variable unless
it is very fresh. Monohydrate has much less of this problem.
These can be used interchangeably by correcting for the formula weight.
124 parts
of monohydrate is equivalent to 106 parts anhydrous.
If you have sodium carbonate of questionable freshness, you can heat it
in an enameled
pot or crucible furnace just like I said to make carbonate from baking
soda. This ensures
moisture and carbon dioxide absorbed from air is removed. (The result is
sodium carbonate
anhydrous.)
Received on Fri Dec 17 15:02:53 2004
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