Test for C Harris Temmoko Red Iron Glaze

[Randy McCall]

 

Hour hold at 1650 F,

 

Recipe Name:  C HARRIS TEMMOKU

Cone:  6     Color:  TEMMOKU
Firing:  Oxidation     Surface:  Glossy

Amount     Ingredient
18.6          Nepheline Syenite
8.5          Gerstley Borate--1999
9.3          Dolomite
9.3          Talc
18.6          Ball Clay Number 1
28.2          Silica
7.5          Bone Ash

100         Total

               Additives
11          Iron Oxide--Red

Unity          Oxide
.104           Na2O
.032           K2O
.359           MgO
.505           CaO
1.000          Total

.323           Al2O3
.094           B2O3
.005           Fe2O3

2.907           SiO2
.008           TiO2
.067           P2O5

9          Ratio
61            Exp

Comments: 
-----------------------------------
Calculations by GlazeMaster™
www.masteringglazes.com
------------------------------------

[George Lewter]

Your test looks very good. I've fired it on my pots on 3 or 4 occasions and it has alway come out looking great. I sprayed jens juicy fruit around the perimeter of a couple of plates and it seemed to make the c harris in the middle lose some of the red's intensity (more brown in it), but it may have been a fluke of firing as well. I'm down firing manually. How do you feel about your test? This is a gorgeous glaze in my opinion.

[Randy McCall]

George I have been looking for this glaze for a long time. Do you know any glazes that either layer with this glaze good or other glazes that look good with it?

[Randy McCall]

George I wonder if I add some other oxides I can get a semi matt black out of this glaze?

[George Lewter]

You could add 2% cobalt ox and 4% manganese dioxide for black. Make a test batch of that. Then use it to run a Fast-five glaze test with alumina hydrate or calcined alumina to find the amount that gets you a level of mattness you're looking for. With just the colorants, I would expect it to stay glossy. I doubt that you would have to use more than 10% alumina to start losing some of the gloss.

[George Lewter]

Take a look at my photos and let me know if you like any of the combinations there. I think I have photos of everything I've done with C. Harris so far, but I should have new tests out next week.

[George Lewter]

For the record, my recipe is slightly different, though the differences do not appear to make much difference. This is the recipe I used on all the pieces in my photos.
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--1999
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.
-----------------------------------
Calculations by GlazeMaster™
www.masteringglazes.com
------------------------------------