Clay For Shino Glazes - Suggestions?

[Rex Johnson]

To start I've done several iterations of my reduction firings so I don't think that's the problem.

 

I've been experimenting with Tom Coleman and Malcom Davis shinos for a while.

I'm not getting the orange hues I expect, more tan-pink.

 

It's been suggested by a reputable source not to use B-mix and move to something like Soldate 60, possibly a clay with more iron content. That said Soldate 60 doesn't show iron (?), but somethng like LB Blend does.

I'm no clay chemistry expert by and stretch, so I'm grabbing at straws here.

 

B-Mix has been fine for throwing small pieces, and large pieces (sand or grog).

I manage to have a waste/loss rate of about 5%.

Note: I have to buy from Laguna because I can pick up, not ship.

 

I'd like to find a body I can do-all with, forgiving and flexible that would work with the shinos.

 

I'm all ears here...

 

...where's the oranges...

 

 

 

 

[neilestrick]

It all depends on the shino. Malcolm Davis Shino, if it's the same one I used to use, actually looks great on white bodies, even porcelain, but you have to reduce the crap out of it and reduce early (cone 012) to get good color and carbon trapping. Other shinos tend to like darker clay bodies better. I used to use Gustin Shino, and it looked great on dark brown clay bodies but come out too pink on light bodies.

[Rex Johnson]

Neil, what does your reduction firing schedule look like?

 

On this piece any orangey/brown hues you see here are due to a temoku wash sprayed over the MD shino.

(Darker colors are the temoku thicker and RIO.)

Clay body is B-Mix w/grog cone 10 fired to cone 7+. A sooty carbon reduction up to about 900 degrees then a normal yellow flame reduction up to full temperature.

 

[neilestrick]

So you're only firing to cone 7? Have you altered the glazes accordingly? Shino glazes like to get hot, so if you're underfiring them by a couple of cones then you may not get the color you want.

 

Fire in oxidation up to cone 012, then put it into heavy reduction for 45 minutes. Stall it out, don't let it climb during that time. A little free carbon is good to get trapping but you don't necessarily need it to be smoking like a steam engine. After 45 start climbing again in neutral/light reduction until done.

[Rex Johnson]

Got it. I'll try hotter and modify per your suggestions with just shino's next time.

I've been using varying glazes that are variable cone 6-10 like Peter's Black in most firings so I've stuck to in and around the 6-7 temps.

 

The first firing I did with Malcolms I was just shooting in the dark, but I had this one piece on the bottom shelf (hotter) that did go orange.

Been trying to recreate it since. That said it, it was cone 5 clay and began to sag.

 

[rakukuku]

I've found shino does better on a darker clay body like Los Altos. But I've had good results with solvate 60. All cone 10. The main thing is to not get it too thick or it goes white. Best ressults with spraying.  And if you use multiple glazes, we have this saying "Shino first or you are cursed".  Rakuku

[bciskepottery]

I believe Malcom Davis used porcelain . . .

[neilestrick]

I believe Malcom Davis used porcelain . . .

 

Yep.

[Rex Johnson]

 

I believe Malcom Davis used porcelain . . .

 

Yep.

 

Well that's good to know. B-mix is pretty smooth and white, so maybe I should stay on the path I'm on.

 

In reference to the sooty reduction, from what Father Davis quotes (https://studiopotter.org/pdfs/spMD17-33.pdf)...

 

 

Heavy Reduction:

If we want to make soot, the black we see in smoke from a heavy

reduction fire, then we really need to starve the fuel for air.

 

What’s changed? Nothing, except now the kiln is producing carbon! And we can’t get

carbon on our pots, to trap it there later when the glaze melts, unless we starve the kiln for

air so much early in the firing that we make some carbon! We could starve the kiln for air

even more, and have hydrogen leaving the kiln instead of water vapor, but that would be a

waste of good fuel, and the temperature in the kiln would start to fall.

N O T E:

If after our hour or so of heavy reduction to make carbon, we then let the kiln

drift back into oxidation, what happens? The carbon, unless trapped under a coat of melt-

ed glaze, will almost immediately burn away. Maintain reduction until the glaze melts and

traps the carbon!

 

With this updraft Olympic propane kiln I'm using, reduction is pretty much inevitable, or at least very easy to get a reduction firing.

I did manage to get some carbon trapping on a couple pieces by running a pretty high reduction...

[Mark C.]

They make a wood/sagar B -mix as well.

B-mix is a white stoneware

try coating it with porcelain the glazes will pop on porcelain

[Rex Johnson]

They make a wood/sagar B -mix as well.

B-mix is a white stoneware

try coating it with porcelain the glazes will pop on porcelain

 

Problem might be finding a porcelain slip that would handle cone 7-10 methinks...

[Rex Johnson]

Maybe this?

 

"A slip casting porcelain highly translucent from cone 5 to 8. Builds very quickly in the mold and maintains translucent character up to a 1/4" thickness"

S‑3128G Glacier White Liquid Casting Slip  

[Guest JBaymore]

FYI.........

 

Traditional Japanese Shino glaze was/is fired on a body that was very light in color.  Only a trace of iron.  Also the body was/is a very open and non-virtirfied body high in alumina.  The rather dramatic reddish fire color stuff came mainly from iron brushshwork decoration.  The firecolor where the glaze was thin on the body at edges was due to the trace of iron and the high alumina in the glaze rock and the body.... and the mainly soda flux that was present (NOT soluble soda raw material sources like American Shino).  The red firecolor (hi-iro) was often also found around the pinholes (not crawling) that is characteristic of Japanese Shino.

 

Japanese Shino actually was not fired that hot (temperature-wise).  It was heatwork that did the job over a LONG firing cycle.... not absolute temperature.  The stone in japan is traditionally stamper milled... so the tiny particles have sharp thin edges and tend to sinter at the edges well at low temperatures.  American industrial processed materials have rounded milled particles....... and will not work the same.

 

Nezume Shino (mouse gray) requires a slip be applied to the clay body and a more neutral fire atmosphere.  Had a Japanese Shino potter take a bunch of time explaining to me how to get that stuff (mainly due to my poor Japanese language skills).  The slip has a very precise small amount of iron and gosu (impure Japanese cobalt).

 

For the American Shino recipes you are firing,........ you'll typically need more heatwork to get the orange tones.  And also for carbon trap move the really dirty reduction up a tad in start point and hold it a tad longer.  Sooty reduction starting at about Orton cone 012 and maintained up until about cone 08.... then more "clean" normal reduction up til about cone 04 and then neutral up to maturity.  Oxidize at the end... and oxidize the cooling cycle.

 

best,

 

...............john