Marcia Selsor on sat 5 sep 98
Dear Tom,
I tried a test using an acrylic medium over a raku luster glaze.
I painted the test over half of a large slab several years ago. I left it
outside in the sun, shade, snow, etc. This summer it still holds the color
where the untreated side shows significant oxidation -prominent green.
I have read your Ceramic Review article which is very informative.
Thanks for all that information!
Marcia Selsor
I am back in Montana after setting up show in New York and giving talks to
groups across the country!
Tom Buck wrote:
>
> ----------------------------Original message----------------------------
> Bob Wicks:
> I did some research on Raku Lustres (because I was intrigued) and
> I learned some things. My original writeup appeared in UK's Ceramic
> Review, issue 159 (Mar/Apr 96), a copy of which Tony Hansen has available
> at his website, digitalfire.com/education/glaze.
> The Tomato and Copper lustres, as usually formulated, will
> always degrade with time. But as you say, using a clear sealant like an
> acrylic will delay the onset of mud. However, if the buyer/owner places
> the piece in a bright room in direct sunlight, the energetic photons will
> penetrate into the glaze and alter the copper/iron reds or copper metal
> and change them into black oxides and thereby the pots will lose their
> orignal colour and sheen. The bright penny copper lustre is especially
> susceptible to this and no amount of reformulating will change its
> mutability. Just keep it in a cool softlit room and it may last for years.
> However, the Tomato Lustre, by reformulating, will become quite
> stable to energetic photons. I placed one test plate outside all summer
> and it survived quite well, just a very slight darkening.
> The gold lustre survived the summer but it did darken somewhat,
> and lost part of its original bright yellow colour. But I judged the
> reformulation to be acceptable.
> As for Copper Sand Lustre, the original recipe was quite
> deficient in silica, and glass made of P2O5 and B2O3 doesn't have the
> stability of bottle glass (soda-lime silicate). The recipe can be adjusted
> but obtaining the textured surface is a separate matter from glass
> stability. The revised recipe gave a glaze stable to bright sunlight but
> its texture and colour are altered to a degree and may not suit some
> potters.
> However, after my efforts with Raku Lustres, I am convinced that
> stable Lustres can be achieved, and some interesting new effects may be
> possible.
> Good tests.
> Tom Buck
> ) tel:
> 905-389-2339 & snailmail: 373 East 43rd St. Hamilton ON L8T 3E1 Canada
> (westend Lake Ontario, province of Ontario, Canada).
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