Anne Hunt on wed 13 sep 00
To Joyce and all following the recent thread on gold raku glazes:
here's one more -- it took a while to dig it up; just as well I did, as I'm
going back to it.
Talked to Perry at Clay Art Center, Tacoma, today, and asked him about the
pro's/ cons of silver carbonate and silver nitrate. He said that the silver
carbonate is a bit less light-sensitive than the nitrate, but you have to
use @ 25% more to achieve the same glaze effect, so there's not much
cost-savings. He's personally never had a problem with service/shelf-life
of the silver nitrate-based raku glazes. Neither have I; I take the lidded
5-gal. bucket with the glaze, put it in a black plastic garbage bag, and
knot it. Have used it almost two months later; much darker and kinda
foul-looking, but just as effective.
cheers!
anne & the cats, in Sequim
----
Subject raku glaze (^06) is in ClayTimes, Vol 3, No. 1, Jan/Feb '97, pg.43,
under Great Glaze Recipes:
Iridescent Blue-Green Raku [Boy, I musta bin doing sumthin' wrong!]
Gerstley 240
Neph Sy 36
Mason Black Stain 8
Silver Nitrate 6
[And no, it doesn't add up to 100%]
No notes, per se. A "regular" consistency gives a pale gold; thicker
consistency or heavier application gives silver; and downright slurpy gives
a deeper silver going opalescent where it's rilly, rilly thick. I've
been trying other "golds" just for S & G, but am going back to the
above...very reliable, no downside in terms of too thin/too thick in mix or
application.
Tom Buck on thu 14 sep 00
AH:
The problem with AgNO3 vs Ag2CO3 is not cost per se, although on
an availablilty of Ag2O, the two come close, approx $1 per gram. The
nitrate is a very difficult material for potters to handle; it is a very
aggressive oxidizing agent and will do permanent harm if you mishandle the
crystals. agreed though once it is in a glaze mix (water etc.) it is much
less dangerous (bit stull the mis should behandled with care).
If one can find a source of Ag2CO3 (carbonate) at $25 per ounce
($0.88 per gram), then I strongly suggest you use it rather than AgNO3 at
approx $1/g.
we have enough hazards in pottery. why add more?
til later. Peace. Tom B.
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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