Kathy White on sun 19 jun 05
First time question on ClayArt, longtime potter.
I'm having trouble with a copper luster glaze, getting the copper (like a
penny copper) to come out with the first firing. They usually come out a
dark mid-night blue or black. I can usually get quite a bit, if I fire it
2-3 times or use my torch, but I'm sure there must be a better answer which
would save on gas. Here's the Raku glaze formula I'm using:
80 Gerstley
20 Neph.synate
10 Copper Carbonate
10 Red Iron
I've been firing my pieces to between 1790 and 1830 F in my raku kiln. When
I pull my pieces, I immediately place the piece in a garbage can with
shredded paper, some pine needles and I even tried adding a few wood chips
this last time. I flash it once and get a good flash. I've tried it on
Laguna's WSO and Soldate 60.
Any good ideas or new recipes that might work better.
Kathy
Robert Briggs on mon 20 jun 05
William & Susan Schran User wrote:
>On 6/19/05 1:28 PM, "Kathy White" wrote:
>
>
>
>>I'm having trouble with a copper luster glaze, getting the copper (like a
>>penny copper) to come out with the first firing. They usually come out a
>>dark mid-night blue or black.
>>
>>
>
>Perhaps your first firing is not hot enough to sufficiently melt the glaze
>as subsequent firings would.
>I'd suggest when you think the first firing is complete, to let it fire a
>bit longer.
>Bill
>
>
>
Try taking your piece out of the kiln while it's still glowing-hot and
reduce it instantly!
I place some shredded newspaper in a bed of sand - I place the piece
straight out of the
kiln on the media and let it flair up. Then cover it immediately with a
'small' metal container
and cover the edges of the container with the sand to start reduction.
Leave the pottery in
reduction for only 10 - 15 mins. The copper penny should look like
orange chrome and the
raw clay areas will be very, very black. Check out my website for some
examples in the
raku section.
Robert Briggs
www.corvusmoon.com
Patricia Dailey on mon 20 jun 05
Hi,
I read once that you have to get your pot into the container and the lid on before it hits 500
degrees. Luster glazes on pots that stay in the air too long have colors that are not copper penny.
They tend to be turquoise, green, brown (with Iron in the glaze) or blue (with cobalt in the glaze).
I have tried leaving the kiln on very low, while pulling, and that seems to help. So that the first
pots are just about as good as the last ones pulled. I also add bismuth subnitrate to my glazes,
and I think they are brighter for that, as the bismuth is a good melter, and that may be a help as
well.
Hope that helps.
Patricia
William & Susan Schran User on mon 20 jun 05
On 6/19/05 1:28 PM, "Kathy White" wrote:
> I'm having trouble with a copper luster glaze, getting the copper (like a
> penny copper) to come out with the first firing. They usually come out a
> dark mid-night blue or black.
Perhaps your first firing is not hot enough to sufficiently melt the glaze
as subsequent firings would.
I'd suggest when you think the first firing is complete, to let it fire a
bit longer.
Bill
Jane Murray-Smith on tue 21 jun 05
Hi Kathy (is this Kathy from Tofino?)..
I have been watching the answers to your question hoping to find an answer
as well...I sometimes get what you are talking about, but never whole
pieces; just patches on pieces, and with a copper matte glaze as
well...we're talking dark gun metal gray and blue black on mine. I was part
of a raku demo last month and someone else brought their reduction system,
(bed of sand, coloured flyer paper sheets flat on bottom, take the very hot
pots out, cover with tons of shredded copy paper, cover, burp after a while
a bit. Most of their stuff was gorgeous, but they too got some dark
blue/black pieces. It was not dead calm, so perhaps the breeze cooled the
pieces too much..
I use a cedar bed and shredded paper..
I feel your pain!.... My pet peeve is getting the avacado or rusty matte
patches on a otherwise beautiful satin matte rainbow of colour...and I have
no idea what does it...it seems you can hold a theory in raku until the next
firing when it is proved wrong!
Jane
----- Original Message -----
From: "Kathy White"
To:
Sent: Sunday, June 19, 2005 10:28 AM
Subject: Copper Luster Glaze
> First time question on ClayArt, longtime potter.
>
> I'm having trouble with a copper luster glaze, getting the copper (like a
> penny copper) to come out with the first firing. They usually come out a
> dark mid-night blue or black. I can usually get quite a bit, if I fire
> it
> 2-3 times or use my torch, but I'm sure there must be a better answer
> which
> would save on gas. Here's the Raku glaze formula I'm using:
>
> 80 Gerstley
> 20 Neph.synate
> 10 Copper Carbonate
> 10 Red Iron
>
> I've been firing my pieces to between 1790 and 1830 F in my raku kiln.
> When
> I pull my pieces, I immediately place the piece in a garbage can with
> shredded paper, some pine needles and I even tried adding a few wood chips
> this last time. I flash it once and get a good flash. I've tried it on
> Laguna's WSO and Soldate 60.
>
> Any good ideas or new recipes that might work better.
>
> Kathy
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
| |
|
