Tom Buck on sat 5 jun 99
Sorry, Linda, but I made the most common Chem 101 error in calculating the
equivalences of Silver Carbonate and Silver Nitrate (see below). And got
one Molecular Weight (MW) slightly wrong.
MW of Ag2CO3 = 276 MW of AgNO3 = 170 (not 176)
No. of Hydrogen equivalents: carbonate = 2; nitrate = 1.
So 276/2 = 138 is the same as 170/1 = 170... or recasting it:
100 grams of Carbonate is equivalent to 123 grams Nitrate;
OR 81 g Carbonate = 100 g Nitrate.
In raku work, though this 19% difference would hardly be noticed.
Again, good tests.
Tom Buck ) tel: 905-389-2339
(westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street,
Hamilton ON L8T 3E1 Canada
---------- Forwarded message ----------
Date: Fri, 4 Jun 1999 10:26:15 -0400 (EDT)
From: Tom Buck
To: HandsInCla@aol.com, clayart forum
Subject: Re: Silver Nitrate/Silver Carbonate
Sure, Linda, Ag2CO3 will work just as well as AgNO3 (nitrate). Handling
it is a bit different though. The nitrate is a strong oxidizing agent, use
rubber gloves, full protection of eyes and skin. Also it is highly soluble
so it goes into the water first, and then the glaze solids, and do not
make the glaze mix thin, keep it close to brushing density (1.65
grams/mL). The AgNO3 will form Ag+ ion when dissolved in water, and it is
the ion that transfers to the pot as adhered material. And when fired and
reduced the Ag+ goes to Ag metal giving the gold sheen.
The carbonate, a yellow powder, is not soluble at all (very
slightly), so it is not as hazardous as the nitrate. You'd likely get best
results by dry blending the powders before adding the water, and screening
the glaze to disperse the solids well. Otherwise you may getting
flecking/spotting of the gold sheen.
The nitrate is generally more freely available than the carbonate
but either will do. And since the Molecular weight of Nitrate is 176 and
the Carbonate is 276, use more carbonate, for every gram of nitrate use
1.6 grams of carbonate, and you'll have the same amount of Silver (as
metal) in the glaze.
Good tests. Tom.
Tom Buck ) tel: 905-389-2339
(westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street,
Hamilton ON L8T 3E1 Canada
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