Norman van der Sluys on sat 27 may 00
Copper matt usually requires a THIN coating, best accomplished by spraying. I get
good results from a garden sprayer ($15 at Walmart) but some are better for this
than others. I bought a second sprayer which did not give me even enough results.
I used that one on the garden now :o)
Norman van der Sluys
TheClosetPotter@AOL.COM wrote:
> Hi.
>
> I attended a Raku firing (my third) and brought along some recipes I mixed up
> to try. Among them was a Copper Matt, or, perhaps, THE Copper Matt:
>
> Frit 3110 10
> Copper Carbonate 90
>
> I added some CMC to help the mixture better adhere to the bisque for
> transport after raw glazing which worked fine.
>
> I used a sample piece on which I applied one, two and three thin coats of the
> mixture. It all came out black as if the mixture completely fired out. I
> was told that perhaps this recipe will only work when sprayed on. I wonder
> if this is so; I hope not as I do not yet have the equipment to spray with.
>
> While I have no idea at what temperature the kiln is fired to as the
> temperature is not measured in any way, I do know that it is the melting or
> maturing of the standard Clear (or White Crackle) glaze (80 gerstley/20
> nepheline) which determines when all the pots are removed for reduction. Can
> someone tell me at what temperature it is that the White Crackle matures?
>
> I wonder if the temperature at which the White Crackle glaze matures is too
> hot for the Copper Matt. I attend the Raku firings as part of a studio
> workshop event and for best results should use Raku glaze recipes that mature
> at the same time as the White Crackle.
>
> Does anyone have any suggestions on how I might still be able to use the
> Copper Matt successfully even at the same temperature as the White Crackle?
> Or, perhaps someone might suggested another method of application?
>
> Thanks in advance for any assistance.
>
> Following are the other three glazes I mixed up and used at this Raku (I
> realize that while they are not new recipes (except for Karen Shapiro's),
> they are new to me and thought other's who are new to Raku might wish to have
> the recipes and comments):
>
> Blue Hawaiian Raku (CM, Sept. '98)
>
> Gerstley Borate 80
> Bone Ash 20
>
> Tin Oxide 1.3
> Copper Carbonate 5
> Cobalt Oxide 2.5
>
> This glaze reliably produced a lightly textured matt lustre capable of blues,
> purples, reds and copper. It worked best for me when 2 thin coats were
> applied (I reduced in newspaper). Everyone seemed to like the results so it
> will likely become a staple for us.
>
> Copper Emerald Green Raku (Steve Forbes-deSoule, Wheel Thrown Ceramics)
>
> Frit 3134 43
> Gerstley Borate 38
> EPK 12
> Flint 7
>
> Copper Carbonate 6
>
> This glaze produced a smooth, satiny lustre capable of a variety of colors.
> Again, 2 thin coats (reduced in newspaper) gave good results but, on the test
> piece, three coats was reflecting more of the Emerald color and I will try
> using three coats next time. It wasn't used much so I don't yet know how
> reliable it is; I'll try it again at my next Raku firing.
>
> Killer Cobalt (Karen Shapiro/Clayart) (Thanks Karen!)
>
> Gerstley Borate 75
> Nepheline Syenite 25
>
> Copper Carbonate 3
> Cobalt Carbonate 6
> Barium Carbonate 5
>
> I used two coats and reduced in newspaper; the glaze went completely glassy
> copper with no trace of blue. I will try using a thicker application next
> time (keeping in mind that Karen described it as a runny glaze), and I will
> try removing it from the reduction container sooner to prevent it from
> completely reducing to copper.
>
> Any suggestions on this glaze? I've never tried reoxidizing sections of a
> pot with a blowtorch; does anyone use that technique, can describe it and
> think it might be useful here?
>
> Thanks again,
>
> Linda Paul
> TheClosetPotter@aol.com
> Kew Gardens, New York
>
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