[Clayart] Pinholes in two tenmokus

David Woof woofpots at hotmail.com
Fri Jul 5 21:44:54 EDT 2019

Hi Bob,
Here is a true cone six that works very well for me.  I still give credit to "V's Temmoku" although I've reformulated, tested and settled on a fourth generation away from the original. I remember Ron and John also working with variations as well.

I always sub out "Ghastley" Borate with 3134, and adjust silica as needed, I also drop Lithium to under 3% if used at all. (in this case not at all with no adverse consequences)

I see Ron's advice and he is dead center on about pinholes and slow cooling down fire. I hold at 2130f in Seg 3, ( extra time to off gas and seal pinholes) and when cone 6 points to 8 o'clock during Seg 4, I manually jump to Seg 5 which begins a cool down and hold at 1900f for 5 hrs. Then a controlled cool down to 1500f for 2.75 hrs whereupon the kiln shuts down and cools at it's own pace.  No pin holes and the glazes get time to work their magic. Mouth watering passionate moans and sighs!!!! Can't wait to get another load up and going.

My "V's 4th Generation Temmoku Gold"

Cornwall stone............61.0
Red Iron oxide.............10.0


Shot of Darvan 11 because I deflocculate most of my glaze slops!!!!

***Glossy red brown splashed with gold flecks.

***On white clay body may get "eggplant" coloration.

***On really dark brown body get darker brown and flecks not so visible.

#### to mix things up: sub R I Ox with 2% cobalt Carb for silver speckles.

Now gotta get ready for the Port Orford Farmers Market.
Pottery for sale....Kid's Clay Table.....Wheel Demo.......Cris works the table, sells my pots, her Novels, and promotes her Pod Cast with the Tag line " Let Me Tell You a Story"..... Roneywrites.com.

Coming over your way soon maybe it will work to have coffee....


From: Clayart <clayart-bounces at lists.clayartworld.com> on behalf of Bob Johnson <impaladrive at gmail.com>
Sent: Tuesday, June 25, 2019 7:36 PM
To: Clayart international pottery discussion forum
Subject: [Clayart] Pinholes in two tenmokus

Looking for your expert advice yet again! I have two cone 6 tenmoku glazes
that are beautiful--when they work--but they often get pinholes. This seems
to happen more often in the front of the kiln, where the burners in the
rear project their flame. I suspect that they are getting a little more
exposure to the flame. It doesn't happen with my other glazes.

I have tried building a low bagwall on the shelves that seem most
vulnerable, using scraps of soft brick, but that didn't solve the problem.
Pots at the rear of the kiln are less likely to show pinholing--but not

So, what do you think? Where should I start experimenting next? What about
decreasing the flux just a bit? Other suggestions?

Oh, and I usually fire them on white stoneware in a neutral-to-oxidizing
atmosphere, with full oxidation at the end--so I can get just a little
tea-dust effect. (Reduction gives too much.)

Here are the recipes for the two glazes.

*Tea Dust Tenmoku*
Whiting  10.5
Pemco frit P-25   26.3
Alberta Slip  62.3
Add: RIO  5

*Tenmoku Gold*
Cornwall Stone  67.45
Dolomite  7.86
Gerstley Borate  3.37
Lithium Carb  6.17
Silica  6.17
Whiting  8.98
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