Karen Shapiro on sun 17 jan 99
Hi Clayarters,
I am working with an article by Tom Buck -- "First You See It Then You Don't"
-- about reformulating raku glazes to be more durable. He calls for borax
"decahydrate" -- what's the difference between this and "borax". My supplier
doesn't know what it is. I have been using the "gold lustre" and am having
trouble with it. Not only is it almost impossible to brush on (CMC doesn't
seem to help), but it fades faster than any luster I've evern worked with.
Gold Lustre: Gerstley borate 87
Nepheline sye 13
Tin oxide 2.2
Bismuth subnitrate 4.4
Silver nitrate 4.4
When it works, it's a fabulous rich gold; when it doesn't, I get either grainy
flecks or no flashing.
Any help much appreciated.
Karen in Sonoma
Karen Shapiro on mon 18 jan 99
Hi Clayarters,
I am working with an article by Tom Buck -- "First You See It Then You Don't"
-- about reformulating raku glazes to be more durable. He calls for borax
"decahydrate" -- what's the difference between this and "borax". My supplier
doesn't know what it is. I have been using the "gold lustre" and am having
trouble with it. Not only is it almost impossible to brush on (CMC doesn't
seem to help), but it fades faster than any luster I've evern worked with.
Gold Lustre: Gerstley borate 87
Nepheline sye 13
Tin oxide 2.2
Bismuth subnitrate 4.4
Silver nitrate 4.4
When it works, it's a fabulous rich gold; when it doesn't, I get either grainy
flecks or no flashing.
Any help much appreciated.
Karen in Sonoma
Sheilah Bliss on tue 19 jan 99
In a message dated 1/17/99 5:02:47 PM, Rakukaren@AOL.COM writes:
<trouble with it. Not only is it almost impossible to brush on (CMC doesn't
seem to help), but it fades faster than any luster I've evern worked with.>>
Hello RakuKaren -
Sorry.... Wish I could offer help with the borax decahydrate. I'd like to
hear something about that stuff too. But while we're waiting, here's a
slightly different recipe for raku Gold Luster - from a Robert Piepenburg
book:
Gold Luster - raku
Gerstley Borate 80.
Cornwall Stone 20.
Silver Nitrate 2.
Tin Oxide 1.
It brushes on fairly well, although I'd recommend using an artificial bristle
brush. Tends to be hard on Japenese bamboo brushes...
Makes a nice gold when the firing goes right. If the rest of the glazes come
out with good color, so does this. If overfired, the gold pales to a speckled
yellow... almost a reptilian or fishy look. I've heard that gold luster
fades, but so far, I haven't noticed any change in a piece I fired over a year
ago.
Good luck!
Sheilah Bliss
in Spokane WA where we're getting both snow and rain at once (snain? or rown?)
....so snow flakes and rain drops = snain flocks? or rown drapes? Our
weather's getting complicated....
Tom Buck on tue 19 jan 99
Hi Karen:
As you saw in my article/technical report, my gold revisions
worked ok but I was not entirely happy because I got too much foaming (as
a result of the high level of outgassing). My gold pots still look gold
although the hue faded a bit after summer months in the bright sun.
Borax (sodium borate) can be sold by a chemical supplier as
borax anhydrous, ie, Na2B2O7, or Borax Pentahydrate (farm-grade "borax"),
ie, Na2B2O7.5H2O, or Borax Decahydrate (washing machine "borax", "mule
train"), ie, Na2B2O7.10H2O.
I explain in the article (please reread) that the Decahydrate form
is unreliable if left sitting around for a while because it may lose some
of the water of hydration (which is part of its crystalline form), or it
may gain some moisture from the air. Either event changes its molecular
weight and therefore makes a change in what you weight out to go into a
recipe.
I am surprised that your dealer was unaware that borax could come
in the three forms... my dealer here will supply me with borax anhydrous
or borax decahyrate most times, and occasionally also stocks the
Pentahydrate when he can get it at a reasonable price. The Pentahydrate
(farm borax) is the best buy if you can find it.
Bye for now.
Tom Buck ) tel: 905-389-2339
& snailmail: 373 East 43rd St. Hamilton ON L8T 3E1 Canada
(westend Lake Ontario, province of Ontario, Canada).
Karen Shapiro on tue 19 jan 99
Hi Sheila,
Thanks for the Piepenburg gold formula -- I'll try it.
Tom Buck answered me off-line about the borax decahydrate:
"Borax can be sold by a chemical supplier as borax anhydrous, i.e. Na2B207, or
Borax Pentahydrate (farm-grade "borax"), i.e. Na2B207.5H20, or Borax
Decahydrate (washing machine "borax", "mule train"), i.e. Na2B207.10H20."
So I'll be buying some washing machine borax to try.
Karen in Sonoma
MR WENDELL R RIDENOUR on fri 22 jan 99
My teacher told me to try tsp sold at hardware stores...for Terra
Sig.....Do you have any input on this? Ellen
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