Is it possible to fire in oxidation for shino glaze?

[leopold]

Hi  everyone,

I have an electric kiln for my works. I have a shino glaze recipe on the below:

Nepheline Syenite 50%

Spodumene 15%

Kaolin 20%

Soda Ash 10%

Redart 5%

If I try on the atmosphere of oxidation, is that possible? I think that would be weird, or someone can help to improve this recipe.

Thanks

 

[JohnnyK]

Your best bet would be to make up some test tiles and about 100 grams of your glaze and run some tests. The test tiles should have some contours so that you can see how the glaze breaks over the ridges and in the valleys. If you have success there, then move on to the rest of your works...

JohnnyK

[Callie Beller Diesel]

It's possible, yes. They will not have the same warm toasty colours, and there will be no carbon trapping though. As Johnny says, make some test tiles to see what they do. 

[neilestrick]

To develop the warm orange/red tones of a classic shino, reduction is required. In oxidation it will be a pasty white color. You could experiment with localized reduction, though, using silicon carbide in the glaze to create reduction within the glaze itself, rather than in the atmosphere of the kiln.

[leopold]

13 hours ago, neilestrick said:

To develop the warm orange/red tones of a classic shino, reduction is required. In oxidation it will be a pasty white color. You could experiment with localized reduction, though, using silicon carbide in the glaze to create reduction within the glaze itself, rather than in the atmosphere of the kiln.

Well noted, I will make up some test tiles to test based on the original recipe to see what they do in the oxidation atmosphere.

In the other side, I would also test your suggestion. If I using silicon carbide, which material in the original recipe should be reduced?

Thanks for your help?

[liambesaw]

There's an old ceramics art daily post about visual arts center shino, which is a cone 6 shino that you can mix and spray with different concentrations of iron to get a toasted look.  I wasnt too impressed but it did look cool.

[neilestrick]

10 hours ago, leopold said:

Well noted, I will make up some test tiles to test based on the original recipe to see what they do in the oxidation atmosphere.

In the other side, I would also test your suggestion. If I using silicon carbide, which material in the original recipe should be reduced?

Thanks for your help?

No need to reduce any other materials. Silicon carbide is added in a very small amount, like 0.2%, and a very fine mesh, like 600-1000 mesh. It'll take a lot of testing, if it works at all.

[Joseph Fireborn]

From my testing with SiC. I found that the best results required glazes with good melts. Shino is a stiffer glaze usually, at least all the shino's that I liked. Usually, the SiC just made it bubble and didn't produce any visible reduction that I could see. I was using a 1200 mesh SiC. 

However this doesn't mean it isn't possible, it just might take a lot of testing to get some results, so be prepared to go down a rabbit hole.

If I was going to approach this again, I would use a currie grid for the shino recipe you wanted to try, then I would add a tiny amount of SiC to each cup and do another grid, and repeat this process 2-3 times. Then I would fire those tiles and look for any signs of reduction and try to figure out which combination of flux, clay, silica starts to get the best results. Then proceed from there.

Anywho! Good luck and please post any positive results you get!

[oldlady]

what about firing in a saggar lined with combustibles?

[neilestrick]

17 minutes ago, oldlady said:

what about firing in a saggar lined with combustibles?

That could work, but all that carbon will leak out and impact the kiln elements. It's fine if you don't mind shortening your element life. Might be a worthwhile trade-off if the pots are amazing. The benefit of doing it in an electric kiln is that you can do a slow, controlled cooling cycle, which Shino love.

[Magnolia Mud Research]

Musings on using shino recipes in oxidization kiln.

One can always fire any glaze (commercial or home brewed) on any clay body to any temperature (within the energy capability of the kiln) in any kiln; The major question is will the result be a "mess" or will the result be something interesting.  The only way to be sure of the answer is to "TRY IT & SEE"!  Comments from colleagues, forum posts, magazine articles, or your favorite barista may provide support for or against the experiment, but only the experiment in your kiln, using your materials and techniques  will answer  the "What happens if I do such and such" question.  If the experiment is new to you, a wise thing to do is to conduct the first suite of experiments with caution to avoid any "mess" becoming a catastrophe by using catch bowls for runny glaze or clay melt down. 

The shino glaze developed in Japan was a stiff white glaze with orange to red edges where the glaze stopped and the raw clay began.  The color, I my opinion, is due to the optical properties of the very thin edges of the fired glaze.  I see that effect along the edges of thick application of shino on all stoneware and also on white porcelains and b-mix type clay bodies. The glaze does respond to additions of iron oxides from the clay bodies and from added iron containing ingredients.  My advice is "TRY IT & SEE"!  

My current glaze assignment (this afternoon actually) is to add additional ingredients as colorants to a shino recipe similar to  leopold's recipe  for the just the "TRY IT & SEE" reasoning.  Red iron oxide up to 16% and Rutile up to 16%.  Why 16? Because I am starting at 1 % and doubling to 2, then 4, then ... . (100 gram batch, add iron and mix, dip, add more, dip, etc.)  The experiment is a scouting experiment.  If something interesting appears, then follow that lead; not interesting, then make notes and move on.  

LT
 

[neilestrick]

The mechanism by which shino glazes develop their orange color is similar to flashing- small amounts of iron reducing and then re-oxidizing during cooling. The color is only at the surface. If you scratch it, it's white underneath. You do not need to have high iron clay bodies in order to develop color in a shino. Some may develop deeper colors on a dark body, but it's not a requirement, and it depends on the glaze. For example, Malcom Davis Shino has only 0.78% iron in it, and develops the best color on porcelain bodies; Gustin Shino has no added iron, just what's present in the ball clay, and develops beautiful deep orange colors on grey stoneware bodies.

[Cline Campbell Pottery]

Here is a recipe for a glaze with the word 'shino' in it's name.  I've found it doesn't have the orange peel texture of the ^9-10 glazes or the orangey colors of reduction shinos.  It could meet some of your needs.  Try 100 grams and see how you like it.

Cynthia

 

Falls Creek Shino ^5-6

Gerstley Borate                 18.7

Lithium Carbonate           6.5

Soda Feldspar                    9.4         (Minspar 200)

Alberta Slip                         56.1       (Albany Slip Substitute)

Silica                                    9.3

Superpax                            9.4         (Zircopax)

Tin Oxide                            4.7

[neilestrick]

There are a lot of cone 6 'Shino' glazes out there. Most are not a true shino, but have some of the characteristics of a shino, such as a warm orange-ish color. If you are a lover of true Shino glazes, they tend to fall short.