Comment

Comment by Norm Stuart on March 26, 2013 at 9:28pm

Touchstone Red has so much red iron oxide it reminds me of Aventurine Iron Saturation glazes I've tried.

Frit 3195 40.00
F-4 Feldspar 13.00
Talc 18.00
EPK 6.00
Wollastonite 5.00
Silica 18.00

One of these Aventurines splatters while firing which is not nice. I was trying to find a way to duplicate Amaco Jewel Brown which forms Iron Silicate crystals or something on a black or dark brown background.

Linda Arbuckle often states in her hand-out that she hasn't tried this glaze, and no photos, so I consider a lot of her recipes as "a rumour of a glaze" rather than an actual glaze recipe.

65.9%    Aventurine  ^04  John W Conrad
39.7%    Silica
38.8%    Borax
15.2%    Red Iron Oxide
7.0%    China Clay
2.7%    Boric Acid
2.2%    Barium Carboate


105.6%    Aventurine  ^04  John W Conrad
39.7%    Silica
38.8%    Borax
15.2%    Red Iron Oxide
7.0%    China Clay
2.7%    Boric Acid
2.2%    Barium Carboate

http://lindaarbuckle.com/handouts/glz_hg_lowfire.txt       

124.00%    Aventurine (Brown Iron with Coppery Crystals)
75.0%    Gerstley Borate
25.0%    Silica, Imsil A-25 - Si 46.75%
24.0%    Iron Oxide - Red 4284 Ferric Oxide
       
http://lindaarbuckle.com/handouts/glz_hg_lowfire.txt       

121.0%    Aventurine ^04  crackle
70.0%    Frit 3269
15.0%    Boric acid
7.0%    Whiting
3.0%    Lithium carbonate
5.0%    Silica
20.0%    Red iron oxide
1.0%    Bentonite
6.0%    Barium Carbonate - makes glaze reddish
small metallic glitter crystals. Boric acid is soluble - mix glaze fresh
apply thick or glaze will be dull brown.

Comment by Norm Stuart on March 25, 2013 at 10:06pm

I also pulled this "Persimmon" glaze out of the kiln made with Iron Oxide Red Precipitate.

http://cone6pots.ning.com/forum/topics/recipes-for-testing

I'll try refiring this at Cone 06 to bring out more red, as George Lewter relates Lana Wilson suggested.

It's certainly a far cry from the photo below of Persimmon Red fired at Cone 10, probably in reduction, shown on Promethian Pottery.

http://prometheanpottery.wordpress.com/2009/12/

Comment by Norm Stuart on March 25, 2013 at 9:46pm

Others have come to similar conclusions ten years ago  (and likely fifty years ago and five hundred years ago). Because of "trade secrets" I'm certain there's been a lot of reinventing the wheel going on in ceramics since it began.  Just like Europeans creating majolica when attempting to reverse-engineer China's porcelain technology.

It was interesting reading declassified Army research papers, published just after WW-II, which recounted attempts to reverse-engineer the chemistry of gold and other metal lusters because the process was secret to German firms like Meissen and there proved to be military uses for applying thin films of metals on ceramics.

http://www.potters.org/subject61502.htm/

Paul Lewing on tue 11 feb 03
on 2/10/03 7:52 PM, Carol Tripp at cjtripp@HOTMAIL.COM wrote:

> I'm working on Michael Bailey's brilliant iron orange, and it only tuns
> out
> dull brown. Has anyone tried it and have any suggestions?

All of these iron reds are very, very dependent on two variables (at least).

One is the particular kind of iron you use. When I first started testing them, I tested black iron, yellow iron and seven different kinds of red iron.

You want to use the iron that is the brightest color before it's fired to get the brightest color after firing. And the firing cycle makes a huge difference. Slow cooling is probably a must.

Paul Lewing, Seattle

 

Comment by Jeff Poulter on March 25, 2013 at 7:49pm

I also found a couple of variations for a glaze called Touchstone Red that I want to try as well. Jeff

Comment by Jeff Poulter on March 25, 2013 at 7:46pm

Hi Norm
I have been reading in some archives where it says to hold down at 800c for Iron Reds. I had a crocus red that came out more brown over the weekend. It came out perfect on the test but not on the pot. It was bigger so I had to fire it in my L&L instead of the Skutt. I know my L&L fires hotter than my Skutt. One of these days I need to figure an offset so they fire more equally. I have had iron reds fire better at ^5. I think I will try your cool down and hold on my next fire. I didn't have time to mix up the orange street but I will this weekend. Jeff

Comment by Norm Stuart on March 25, 2013 at 6:58pm

I notice you slow cool at 50•c/hr to 962•c.

In centigrade our 50F/hour slow-cool is,  10•c/hr from 982•c to 815•c, which is much slower, but I think the big difference is the clay as seen below on our brown clay.

Comment by Norm Stuart on March 25, 2013 at 6:28pm

Orange Street fires with a shiny surface on brown clay in our kiln as well.

This is the same glaze as above on iron rich brown clay, fired the same way to Cone 6 with an hour hold at the top and a slow-cool of 50F between 1,800F and 1,500F - just as with the white tile above which fired matte.

On brown clay I'd reduce the Red Iron Oxide as there's an equilibrium reaction going on with the iron in the clay, even though only black iron oxide is supposedly a flux. So instead of 12% iron oxide red precipitate I'd try 9% or so.

Comment by Jeff Poulter on March 22, 2013 at 2:01pm

It is thicker on the left side & you can see the surface is more of a solid color.  I will put this in my next bisque to see what that does to it.

Comment by Norm Stuart on March 22, 2013 at 12:47pm

I've noticed there's obviously an equilibrium reaction between the iron level in a clay and the iron in a glaze during the melt.

Iron in a glaze always seems to first find its way to the surface of a white clay, with only the amount of iron unreacted with the clay remaining in the melt. Likewise many glazes on a high iron clay develop spots resulting from iron migrated out of the clay and inti the final glaze.

Your glaze tile resembles "aventurine" iron saturation glazes I've tried using 15.2% iron oxide, where the glass in the glaze crawls away from the refractory iron oxide.  It seems likely I'm losing part of the iron oxide into my white clay to get the result I have. I'll try to find some piece of bisqued high iron clay to try Orange Street on in our kiln.

Comment by Jeff Poulter on March 22, 2013 at 12:01pm

Here is the pic.  Had to take it inside as it is snowing again today.  Will spray a pot tomorrow if the weather cooperates.  Also will do some testing subbing out the Yellow Iron Oxide and also some layering.

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