Alicia Claussen glazes with feldspar – C6?

[Lawrence Weathers]

I would like to make up the following Alicia Claussen glaze. But I don't know what she means by feldspar – C6.. Insight doesn't list such a beast and there are lots of kinds of feldspar. What do you think it is?

Recipe Name: Orange glaze with blue crystals

Cone: Color:
Firing: Surface:

Amount Ingredient
5 Kaolin--EPK
15 Silica
24 Zinc Oxide
13 Whiting
7 Lithium Carbonate
36 Feldspar--C6

100 Total

Additives
1 Nickel Oxide

[George Lewter]

I would just do test batches with a potash spar and another with a soda spar. The only thing I can think of that might possibly be referred to as C6 spar is nepheline syenite, which is often given as the first feldspar substitution to try for replacing Custer spar to take a cone 10 glaze down to cone 6.

[Lawrence Weathers]

I was hoping not to have to do that but that may be the alternative.

I hope you're enjoying Florida. I've lived in both Miami and Tampa areas

[Norm Stuart]

Using Alisa Claussen glazes you'll run into MOK-623, a European frit.

http://digitalfire.com/4sight/material/johnson_matthey_frit_623_647...

These Sankey Database glaze recipes called for Ferro Frit 3134, and MOK-623 was her closest substitute.

I used this less than ideal substitution with soluble fluxes and a little too much calcium oxide.

 75.0%  Ferro Frit 3134
  30.0%  Borax
  10.0%  Soda Ash
   5.8%  Zinc Oxide
   5.3%  Strontium Carbonate
-12.8%  Calcium Oxide

Neither Ferro 3134 nor the mix above create the look of her finished glazes, but using Ferro 3134 creates the glaze the way it was originally.

[Norm Stuart]

I am still bewildered by the variety of feldspars I inherited, Minspar-200, Kona, F4, C6, Custer, G200, and G200-HP.  Many feldspars listed in glazes, or those we have at our studio, are no longer available.  It's still confusing, as you can see I deleted an earlier mistaken version of this reply.

As George said, they're generally either Potash (Potassium / K2O) or Soda (Sodium / Na2O).  I wrote either Soda or Potash on each bag.  My experience and texts say potash spar tends to produce brighter colors. 

I needed Digitalfire to decode them. 

As you can see there is very little difference between soda spars like C6, or Minspar-200.  Insight doesn't have a listing for Minspar 200 so I just choose Soda Feldspar.

http://digitalfire.com/4sight/material/c-6_feldspar_157.html

http://digitalfire.com/4sight/material/minspar_200_1031.html

http://digitalfire.com/4sight/material/custer_feldspar_253.html

But these are different to potash feldspars like Custer and G-200.

http://digitalfire.com/4sight/material/custer_feldspar_253.html

https://digitalfire.com/4sight/material/g-200_feldspar_800.html

If you make one small batch with soda spar, like the original recipe, and another with potash spar you'll quickly see what sort of difference this choice of ingredients makes.  The glaze COEs should be little different.

One day I went to mix up a glaze with cobalt and rutile called "Clear Blue".  It's made with the flux Wollastonite (calcium-silicate), which only I would call a "calcium feldspar". 

I wasn't familiar with the look and feel of different raw materials at the time, so when I went to my "feldspar pallet" I reached into the wrong bag and grabbed G-200 Feldspar (potash-spar) instead.  The glaze COEs are nearly identical, but the look of the glaze is quite different.

Clear Blue made with 13% Wollastonite  --  a less fluid glaze at melt and a little less glossy

Clear Blue made with 13% Potash G200 Feldspar

The difference between soda and potash spars is more subtle than the difference between spar and wollastonite.

I am still bewildered by the variety of feldspars I inherited, Minspar-200, Kona, F4, C6, Custer, G200, and G200-HP.  Many feldspars listed in glazes, or those we have at our studio, are no longer available.  It's still confusing, as you can see I deleted an earlier mistaken version of this reply.

As George said, they're generally either Potash (Potassium / K2O) or Soda (Sodium / Na2O).  I wrote either Soda or Potash on each bag.  My experience and texts say potash spar tends to produce brighter colors. 

I needed Digitalfire to decode them. 

As you can see there is very little difference between soda spars like C6, or Minspar-200.  Insight doesn't have a listing for Minspar 200 so I just choose Soda Feldspar.

http://digitalfire.com/4sight/material/c-6_feldspar_157.html

http://digitalfire.com/4sight/material/minspar_200_1031.html

http://digitalfire.com/4sight/material/custer_feldspar_253.html

But these are different to potash feldspars like Custer and G-200.

http://digitalfire.com/4sight/material/custer_feldspar_253.html

https://digitalfire.com/4sight/material/g-200_feldspar_800.html

If you make one small batch with soda spar, like the original recipe, and another with potash spar you'll quickly see what sort of difference this choice of ingredients makes.  The glaze COEs should be little different.

One day I went to mix up a glaze with cobalt and rutile called "Clear Blue".  It's made with the flux Wollastonite (calcium-silicate), which only I would call a "calcium feldspar". 

I wasn't familiar with the look and feel of different raw materials at the time, so when I went to my "feldspar pallet" I reached into the wrong bag and grabbed G-200 Feldspar (potash-spar) instead.  The glaze COEs are nearly identical, but the look of the glaze is quite different.

Clear Blue made with 13% Wollastonite  --  a less fluid glaze at melt and a little less glossy

Clear Blue made with 13% Potash G200 Feldspar

The difference between soda and potash spars is more subtle than the difference between spar and wollastonite.

[Lawrence Weathers]

I really don't understand what you are saying here

Norm Stuart said:

These Sankey Database glaze recipes called for Ferro Frit 3134, and MOK-623 was her closest substitute.

I used this less than ideal substitution with soluble fluxes and a little too much calcium oxide.

 75.0%  Ferro Frit 3134
  30.0%  Borax
  10.0%  Soda Ash
   5.8%  Zinc Oxide
   5.3%  Strontium Carbonate
-12.8%  Calcium Oxide

Below sounds like a contradiction.

Neither Ferro 3134 nor the mix above create the look of her finished glazes, but using Ferro 3134 creates the glaze the way it was originally.

[Norm Stuart]

Alisa Clausen made all of John Sankey's glazes, most of which are on file here on Cone6Pots  http://cone6pots.ning.com/page/the-sankey-glaze-database and has posted the test tiles you see on her Flikr page.  http://www.flickr.com/photos/glazes/sets/

She had no access to Fero Frit 3134 in Denmark so substituted the closest frit available to her, MOK-623  which also contains 9% Barium, 5.85% Zinc, 5.28% more Boron Oxide, almost 9% more Na2O, and almost 1% less calcium.

I've made the Ferro 3134 glazes with Ferri 3134, and many lack the "interest" she developed.  Her tiles with Mok-623 typically have more glass and are more fluid.

Cassie's Marsala  is a typical example:  http://www.flickr.com/photos/glazes/sets/72157601379998613/

http://cone6pots.ning.com/profiles/blogs/cassie-s-marsala

I may look again and try to develop a better MOK-623 substitute not using soluble Borax and Soda Ash -  I've use both barium and strontium carbonate, but that doesn't seem to make much change.

The glaze on the right clearly has less glass and less flow.  Claussen's version with MOK 623 is just beautiful.  It's what I would have wished for in Waterfall glaze from "Mastering Cone 6 Glases". 

Alisa's  Cornwall stone recipes are also different in look, so perhaps she is using the original Cornwall Stone from the UK, which is no longer available. 

Alisa's generosity was one major reason I've made and photographed these glazes myself.  It's this generosity I find most appealing about the art ceramic community.