Five Earthenware Base Recipes

Originally written 26 Sept 2016

Testing of five different Cone 04 matte or satin base recipes. All of the recipes have very similar ingredients, but different ratios.

These tests weren't ultimately successful as a week later four of them had crazed.

Retesting Julie's Satin (JMBC) and also testing a variation (JMBC revA), revised using hints from Glaze Simulator.

 A. Jackie's Matte via Priscilla Hollingsworth

38  Gerstley borate
10    Lithium carbonate
5    Nepheline syenite
5  Eckalite 2
42  Silica

5% Zircosil



B. Satin Base (from here)

65.5 Ferro frit (4124) 3124
11    Nepheline syenite
5      Eckalite
42    Silica

C. Julie's Satin (from here)

27  Gerstley borate
7    Lithium carbonate
17  Whiting
4    Nepheline syenite
11  Eckalite 2
34  Silica

 D. Hirsh's Satin Matte

32  Gerstley borate
9    Lithium carbonate
17  Whiting
4    Nepheline Syenite
4    Eckalite 2
35  Silica

2% Bentonite

 E. Julie's Matte revised to fix crazing (JM rev A)

27  Gerstley borate
6    Lithium carbonate
17  Whiting
4    Nepheline syenite
12  Eckalite 2
34  Silica

Lucy Burley's Matte

I found this recipe on Ceramic Arts Daily's article about Green, Blue and Turquoise glazes. I love these colours and I'm looking for matte glazes for cone 04 firings.

 I have substituted Strontium carbonate for Barium carbonate.

I did a rough line blend, rough because I started the test using a teaspoon to measure units in the blend and ran out of glaze mix.

Lucy Burley's Matte Glaze Recipe

10    Strontium carbonate
45    Frit 3134
15    Potash Feldspar
15    Ball Clay FX
15    Eckalite 2

Results

I love the colours in these tests. You can't see in the photo but this glaze bubbled at the edges.

I think this is because I didn't add enough water to the glaze mix and it went on very thick.

It isn't very matte either, a little shiny for a matte glaze. I might try to tweak it if I make it again to tone down the shininess and fix the bubbling.

Julie's Satin Triaxial - Blog Ceramique

This glaze test is for another Blog Céramique triaxial - Julie's Satin Base in green/blue

It's based on a cone 04 satin/matte base glaze recipe, which I think is based on the 

popular Jackie's Base glaze found around the net - the ingredients are similar - but this has added Calcium Carbonate (as an opacifier?) and different ratios. I used it on Keane's Earthenware 37 fired in my home kiln, an old Ward.

I mixed this one at home and fired it with a mixed firing of bisque and glazed pieces. One of the benefits of firing to cone 04 is being able to mix loads.

I had problems with reaching temperature as I had the controller programmed wrong and the kiln turned off too early before the cone had bent. Took another hour of fiddling with the controller to get it melted.

I don't think I did slow cool on this firing but it sort of had a soak due to the mistake.

The only substitution is Eckalite 2 for EPK which is unavailable here.

While I had the base mixed I did some extra experiments with cobalt, light blue stain and rutile.

Julie's Satin Base

17    Calcium carbonate
27    Gerstley borate
7      Lithium carbonate
4      Nepheline syenite
11    Eckalite 2 (my substitute for EPK)
34    Silica

In the Triaxial
A was the base glaze,
B was 3.5% Copper carbonate
C was 1% Chrome Oxide

Results

I think I might have made the colour too strong too, I can't remember if I divided the amounts into thirds or just put the whole amount in each corner.

As it is the chrome seems unmelted and has taken on a rough burnt looking texture where it is most concentrated. The colours certainly look different to the sample tests on the BC blog.

Also the glaze has crazed in its base form and on some of the copper side.

I love the finish of this one though and will try to reformulate it to fix the crazing. Has a lovely thick buttery matte texture.