Alisa Liskin Clausen on sun 8 sep 02
Glaze test for Black, cone 6 radix, fired to cone 6 ox.
Glaze tested on white midrange stoneware fired in electric oxidation to =
1220c.
Source: Clayart
Credited to:
Firing ramp:
100c up/he to 600c (212f - 1112f)
150c up/he to 1100c (330f - 2012f)=20
100c up/he to 1220c (212f - 2228f)
cool down max. per hour to 1100c=20
cool 80c per hour to 800c
shut off kiln
Recipe:
78.81 K200 Feldspar
10.76 Gerstely Borate
5.46 Whiting
4.97 EPK
ADD
4.14 Manganese Diox. HAZARDOUS
3.31 Copper Carb.
1.99 Cobalt Carb.
Note: All raw materials are measured up or down to the nearest whole =
decimal. =20
Colorants or additives to a 100 gram test batch are measured in percent =
to the 100 gram test batch.
Substitutions:
Local feldspar for K200
Borax frit for Gerstley Borate
Results:
Lush, covering, even black semi gloss glaze. Black, black, black and =
slightly gun metal. Totally covering where thinner and thicker.
Regards from Alisa in Denmark
John Hesselberth on sun 8 sep 02
Hi Alisa,
While I know this glaze has appeared on Clayart, the original source is
"Making Pottery without a Wheel" by F. Carlton Ball and Janet Lovoos,
p144. It also sometimes gets attributed to Mary Barringer because she
uses (or at least used to) it and passes out the recipe at her
workshops. They both call it Metallic Black Glossy. The only difference
between your version and the original is that the original has manganese
and copper both at 4.1%.
But my real reason for writing is to note that this glaze is a good
example of one that has plenty of silica and alumina (4.16 and 0.65
respectively) -- in fact too much to melt completely at cone 6 even
though it has some boron. It also carries a pretty heavy loading of
colorants--at least at the original 4.1% copper carbonate. The net
results of this is that it leaches pretty badly. In my hands it won't
pass the vinegar test and, if I remember correctly--I don't have my
notebook at hand--leaches about 40 mg/l of copper.
This glaze is, in my opinion, definitely not a glaze for functional
work. Also, in my hands, it is a "spitter", i.e. it spits little dots of
glaze all over the shelves and neighboring pieces. It might do a lot
better at cone 8 with respect to leaching, but I doubt that would have
any effect on its spitting.
Regards,
John
On Sunday, September 8, 2002, at 05:36 AM, Alisa Liskin Clausen wrote:
> Glaze test for Black, cone 6 radix, fired to cone 6 ox.
>
> Glaze tested on white midrange stoneware fired in electric oxidation to
> 1220c.
>
> Source: Clayart
> Credited to:
>
> Firing ramp:
> 100c up/he to 600c (212f - 1112f)
> 150c up/he to 1100c (330f - 2012f)
> 100c up/he to 1220c (212f - 2228f)
> cool down max. per hour to 1100c
> cool 80c per hour to 800c
> shut off kiln
>
> Recipe:
> 78.81 K200 Feldspar
> 10.76 Gerstely Borate
> 5.46 Whiting
> 4.97 EPK
>
> ADD
> 4.14 Manganese Diox. HAZARDOUS
> 3.31 Copper Carb.
> 1.99 Cobalt Carb.
>
>
> Note: All raw materials are measured up or down to the nearest whole
> decimal.
> Colorants or additives to a 100 gram test batch are measured in percent
> to the 100 gram test batch.
>
> Substitutions:
> Local feldspar for K200
> Borax frit for Gerstley Borate
>
> Results:
> Lush, covering, even black semi gloss glaze. Black, black, black and
> slightly gun metal. Totally covering where thinner and thicker.
>
> Regards from Alisa in Denmark
>
Frog Pond Pottery
PO Box 88
Pocopson, PA 19366
Fax or phone: 610-388-1254
Alisa Liskin Clausen on sun 8 sep 02
Dear John,
Yes, the glaze is almost the same as Mary Barringer's recipe CM last year(?)
I have used it on some decorative pots and it has not spit up to now. Now,
with John's
comments, I am glad that I have not used it on bowls, as I like black bowls.
I will
work further with some of Ron's black glazes for functional ware.
I think and say again, I am really glad for this type of cooperation from
Clayart. I can test and post the results, and the John and Ron
can evaluate the glazes. Great teamwork.
regards from Alisa in Denmark
Marianne Lombardo on sun 8 sep 02
Dear Alisa;
I have used the Licorice from Mastering Glazes on porcelain and it is so
very lovely. Rich, dark, covering, black. Yummy.
In my firing this week I am also going to test it on some other stoneware
and I will post the results.
Marianne Lombardo
Omemee, Ontario, Canada
email: mlombardo@nexicom.net
> I will work further with some of Ron's black glazes for functional ware.
Ron Roy on thu 12 sep 02
Is this the one John commented on? - high expansion, alumina is very high
so it may not be properly melted - I would not use it for anything
functional - another clue is the gunmetal sheen - that means oxides in the
glaze could not be held in suspension and are on the surface - waiting to
dissolve in anything acidic.
RR
>Glaze test for Black, cone 6 radix, fired to cone 6 ox.
>
>Glaze tested on white midrange stoneware fired in electric oxidation to 1220c.
>
>Source: Clayart
>Credited to:
>
>Firing ramp:
>100c up/he to 600c (212f - 1112f)
>150c up/he to 1100c (330f - 2012f)
>100c up/he to 1220c (212f - 2228f)
>cool down max. per hour to 1100c
>cool 80c per hour to 800c
>shut off kiln
>
>Recipe:
>78.81 K200 Feldspar
>10.76 Gerstely Borate
>5.46 Whiting
>4.97 EPK
>
>ADD
>4.14 Manganese Diox. HAZARDOUS
>3.31 Copper Carb.
>1.99 Cobalt Carb.
>
>
>Note: All raw materials are measured up or down to the nearest whole
>decimal.
>Colorants or additives to a 100 gram test batch are measured in percent to
>the 100 gram test batch.
>
>Substitutions:
>Local feldspar for K200
>Borax frit for Gerstley Borate
>
>Results:
>Lush, covering, even black semi gloss glaze. Black, black, black and
>slightly gun metal. Totally covering where thinner and thicker.
>
>Regards from Alisa in Denmark
>
>______________________________________________________________________________
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>
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>
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Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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