Jeremy/Bonnie Hellman on tue 27 nov 01
Weathered Bronze is a glaze that changes appearance and color dramatically
when layered with clear or white.
My first attempt at a clear coating on weathered bronze produced a color
only a biologist would love. My daughter called it "pond scum green".
With several different whites, layered over or under, I get a variety of
appearances, most of them quite interesting, but all of them quite different
and none of them anything like plain weathered bronze.
Bonnie
Bonnie Hellman
Enjoying the second week of vacation in snowy Ouray, CO where we have about
30 inches of fluffy, white snow, all fallen within the last 5 days!
----- Original Message -----
From: "Ruth Ballou"
To:
Sent: Monday, November 26, 2001 8:25 AM
Subject: Re: Glaze Mystery aka Why the heck did this happen???
> Both alumina and silica can have profound effects on color response. This
> is one of the variables that the grid shows off so well. The samples
you've
> chosen are moving up the alumina baseline as well as the silica baseline,
> so the change in both is having an effect.
>
> Pete Pinnell recently wrote in about Weathered Bronze Green. Might
help.Try
> the archives.
>
> One other thought..... have you tried putting a thin coat of clear glaze
> over the WBG. Other glazes have been helped by this.
>
> Ruth Ballou
>
> >I am a tilemaker. I want to use Pete Pinell's Weathered Bronze Green on
the
> >floor of a covered patio, but it scratches too easily. So, I decided to
use
> >Ian Currie's grid method to adjust it towards a harder surface without
> >getting too far away from the satin matte finish.
> >
> >The original recipe falls at position #27 in the grid (unity formulas
> >below), so I fired tests of positions 17, 18, 22, & 23. The glazes at
> >positions 18 & 23 are harder, but only glaze #22 remotely resembles the
> >original color. Here's the chemistry:
> >
> >Original recipe:
> >Na2O .36 Al2O3 .56 SiO2 2.98 Al:SI Ratio 5.28
> >K2O . 11
> >MgO .01
> >CaO .02
> >Li2O .05
> >SrO .46
> >
> >In each of the new recipes, the flux values remains the same. The Al,
Si,
> >and Al:Si Ratio values are:
> >
> >Recipe 22 - Al2O3 .65 SiO2 3.19 Al:Si Ratio 4.90
> >Recipe 23 - Al2O3 .66 SiO2 4.13 Al:Si Ratio 6.28
> >Recipe 17 - Al2O3 .75 SiO2 3.42 Al:Si Ratio 4.56
> >Recipe 18 - Al2O3 .76 SiO2 4.39 Al:Si Ratio 5.79
> >
> >Recipe 22 has a noticeably altered color, but is similar to the original.
> >Recipes 17, 18, & 23 are very different - a dull kakhi color rather than
> >green. I graphed these values and the thing that stands out is that the
> >amount of SiO2 is nearest the original value in recipe #22, the one with
the
> >color nearest the original. I'm pretty new at glaze chemistry. Can the
> >amount of silica have such a profound impact on the color response or am
I
> >overlooking something else?
> >
> >These tests were fired in the same kiln load on the same clay. In fact
the
> >test tiles came out of the same bisque load.
> >
> >Electric kiln with Envirovent on throughout firing and cooling. Cone 6
tip
> >completely down and cone 7 just starting to bend.
> >
> >The firing schedule used was:
> >176 degrees F to 352
> >284 1200
> >212 1832
> >284 2052
> >108 2232 hold for 0.5 hrs.
> >
> >Any insight anyone can offer will be most appreciated.
> >
> >Thanks,
> >Wanda
> >
>
>___________________________________________________________________________
___
> >Send postings to clayart@lsv.ceramics.org
> >
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> >
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> >melpots@pclink.com.
>
>
____________________________________________________________________________
__
> 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.
>
Alisa og Claus Clausen on wed 28 nov 01
I have brushed Desert Wash the Weathered Bronze with it resulting in a
slightly harder but smoother surface.
Weathered Bronze base with the colorant 8 Copper carb, called Graphite,
was overlapped with a white matt. It produced a Weathered Bronze green.
The overlap occurred on a rim of a pot that was glazed Graphite on the
outside and
Wodo White on the inside The Green rim was a nice contrast on the
pot. Same result
with 20 x 5 with 12% Zircopax, just glossier.
Otherwise I paint the Weathered Bronze on so thick I think it is a lie, but
that is the way it
works well for me. Gives a good patina green look, a little dry.
Best regards, Alisa
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