C Harris Temoku

[George Lewter]

I mixed a test batch of this about 4 years ago and loved it. I then mixed a whole 5 gallon bucket full, and used it until I ran out last year. It's the only production batch I've ever mixed up. It was used for all the pots that used C Harris Temoku in my pictures through 2012.

It's time for a new bucket full. I'm holding my breath about the results, with some of my raw materials being from new batches. I also am not totally clear on which of three different red iron oxides I used. (A generic, a "Spanish" red iron oxide, or "Special" Red Iron oxide from Ceramic Supply in New Jersey - though I do have more of all three ).

This recipe was posted on the network in discussions under the names of people who have left, and deleted their content, and it seems to have disappeared, so I'm reposting it here.

Recipe Name: C Harris Temoku

Cone: 6 Color: red brown black
Firing: Oxidation Surface: Glossy

Amount Ingredient
27.8 Silica
18.6 Kaolin--EPK
18.6 Nepheline Syenite
9.2 Gerstley Borate
9.2 Dolomite
9.2 Talc
7.4 Bone Ash

100 Total

Additives
11.1 Iron Oxide--Red

Unity Oxide
.104 Na2O
.03 K2O
.356 MgO
.509 CaO
1.000 Total

.355 Al2O3
.102 B2O3
.004 Fe2O3

2.729 SiO2
.002 TiO2
.067 P2O5

7.7 Ratio
6.1 Exp

Comments: Posted on Clayart 1999 by C Harris as a temoku suitable for electric firing. I have a favorite ^6 glaze (C.Harris Tenmoku from the archives) that is it's very best when slow cooled and held at around 1850 for an hour or more.  Pete Pinnell wrote about some tomato red glazes that also profit from slow cool and long holds.
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Calculations by GlazeMaster™
www.masteringglazes.com
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[Donna Kat]

Beautiful!  Do I understand you correctly - You made up a 5 gallon bucket of a glaze using new materials without first testing?  You are living on the edge if I have understood you correctly.  The only success I have had with such a glaze is using Special RIO (synthetic).  Just changing the talc from Nytal to Texas complete lost the red color (turned a muddy brown).  I had to add bone ash to my recipe to get back the color.  A change in cool down can lose the Red.  Not putting it on thick enough loses the red.  If this glaze is that forgiving, it is my new red.  Do you use the recommended cool down?

[George Lewter]

No, I didn't, and won't make 10,000 gram batches of anything, without first doing a test batch. The first glaze batch was extremely reliable from the beginning of the bucket to the end over many firings with and without the cool down holds. I now have a bag of high purity red iron oxide from USpigments.com that I will test along with some of my other RIOs. Will post side by side results here in a couple of weeks.