From: Linas Kudzma (lkudzma@earthlink.net)
Date: 04/24/02-06:21:56 PM Z
Joe,
Are you using potassium carbonate? The solubility of sodium carbonate much
less than potassium carbonate. See the below solubility data:
Potassium carbonate, anhydrous MW 138.21 112g/100ml cold water
Potassium carbonate, dihydrate MW 174.24 146.9g/100ml cold water
Potassium carbonate, trihydrate MW 330.46 129.4g/100ml cold water
Sodium carbonate, anhydrous MW 105.99 7.1g/100ml cold water
Sodium carbonate, decahydrate MW 286.14 21.5g/100ml cold water
The 100 g of anhydrous potassium carbonate in 100ml of water in Sandy's
Pyrocat solution B formula dissolves easily. No doubt Sandy used potassium
carbonate due to it's great solubility.
Incidentally, we should all stop calling this a 100% solution, because this
is incorrect. If we want to express this as a percent weight per weight
solution, then we are saying grams of dissolved compound per 100 grams of
solution. The above is a 50% w/w solution of potassium carbonate in water.
Linas
----- Original Message -----
From: "Joe Portale" <jportale@gci-net.com>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Tuesday, April 23, 2002 10:59 AM
Subject: pyrocat part B question
> Okay folks, I give, how do you keep 100 grams of the carbonate dissolved
in
> 100 mls of water? It has been three days and the best that can be said is
> the "B" is a slurry. For the record, the chemicals are analytical grade
and
> the water is distilled. I have been using the 10% solution B and watching
> the threads on this subject decided to try the 100% solution.
>
> How about this as an alternative, since the formula is calling for 1:1:100
> (or 2:2:100 depending what one is doing), and the 100% shows B actually
> being 1 gram of pot carbonate per 100 mls of water, why not add the
> appropriate amount of dry carbonate to the working solution. If my logic
> works out right, that would be 10 grams per 1000 mls of working solution.
> Just mix the appropriate amount of carbonate to the water then add the A.
> OTOH, why not mix up a big batch of 1% carbonate and add the part A as
> needed? Does the carbonate keep? in solution? Does this sound feasible?
>
>
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