Friday, October 14, 2011

Cone 6 Oxidation Results Group 5

 Cone 6 Oxidation Results Group 5

Thus far I have batched over 120+ different glazes in 300 gram batches, the formulas for which have been found from publicly available sources.  After firing these tests in an electric kiln to Cone 6, I have photographed each and am making them available to potters with the accompanying formulas.

One difference with this Group 5 is that I have introduced a cooling cycle to the firing.  The cycle is as follows and the firing is accompanied by a Cone 6 witness cone.  After 12 consecutive firings, the witness cones are identical from firing to firing.

The firing cycle:

Rate                          Temp                   Hold Time

rA1= 360 F1 = 900 0

rA2= 300 F2 = 1800 0

rA3 =200 F3 = 2016 0

rA4 = 108 F4 = 2197 0.3

rA5 = Full F5 =1800 0

rA6 =150 F6 = 1300 0

rA7 = 0000

To summarize, I fire at a rate of 360/hr to 900 degrees F, then at 300 degrees/ hr to 1800 degrees F, 200 degrees/hr until 2016 degrees F is reached, then 108 degrees/hour to 2197 at which time I hold it at that temperature for 30 minutes.  

The kiln is shut off until a temperature of 1800 degrees F is reached and then turned on to slow the rate of cooling to 150 degrees/hr until 1300 degrees F is reached.  At this point the kiln is turned off and cools naturally.  

I use a Vulcan kiln controller attached to a Paragon QA11 test kiln.  The combination of new elements in the Paragon and new thermocouple and controller has produced consistent heat work from one firing to the next.

Links to Cone 6 Groups 1 - 4 without controlled cooling.

Group 1

Group 2

Group 3

Group 4

 Group 5 results with controlled cooling.

1C (C denotes controlled cooling)

#1        Jen's Juicy Fruit Variation (Red Matte) C/6  


            EPK                             10%

            Gillespie borate             9%

           Nepheline syenite         49%

            Flint                             12%

            Whiting                        11%

            Lithium carbonate       9%

            Soda ash                      10%

            Titanium dioxide         5%

            Red iron oxide             10%


#2 - Jen's Juicy Fruit Variation 2 (Red Matte) C/6        

EPK                             10%

Gillespie borate           9%

Nepheline syenite        49%

Flint                            12%

Whiting                        11%

Lithium carbonate       9%
Standard Ceramic's #487 Red Stain    10%
Soda ash                   10%

Titanium dioxide         5%

 #2 normal cooling same formula


3 - Pete's Tomato Red #3 C/6     


Kona F-4 (Minspar)    33.7%

Frit 3134                     9.8%

Bone ash                     10.7%

Whiting                       3.8%

Magnesium carb          5.9%

EPK                            12.5%

Flint                             23.7%

Bentonite                      2%

Red iron oxide              8%

4 - Tomato Red #13 C/6        


Frit 3134                      10.8%

Nepheline syenite        23.1%

Bone ash                          10%

Magnesium carb          6.2%

Whiting                        7.7%

EPK                               21%

Flint                              21.2%

Bentonite                       2%

Red Iron Oxide                10%

#4 without cooling cycle.

5C with cooling cycle

5 - Tomato Red #13 Pumpkin Orange C/6    


Frit 3134                    10.8%

Nepheline syenite        23.1%

Bone ash                         10%

Magnesium carb          6.2%

Whiting                       7.7%

EPK                              21%

Flint                             21.2%

Bentonite                      2%

Red Iron Oxide               10%

Rutile                            2%

#5 without cooling cycle.

6C with cooling cycle.

6 - Tomato Red #13 with spodumene C/6     


Frit 3134                      11%

Spodumene                  11.2%

Bone ash                      7.9%

Magnesium carb          6.3%

Whiting                        7.9%

EPK                             21.6%

Flint                              21.7%

Neph Syenite               11,8%

Bentonite                     2%

Red Iron Oxide           10%

 6 - without cooling cycle.

8C - with cooling cycle.

8 - Jen's Juicy Fruit Variation (Red Matte) Cone 6   


EPK                            10%

Gillespie borate           9%

Nepheline syenite        49%

Flint                             12%

Whiting                       11%

Lithium carbonate       9%

Soda ash                      10%

Titanium dioxide         5%

Black Iron Oxide        6%

 8 - without cooling cycle.

12C - with cooling cycle.

12 - Jen's Juicy Fruit Variation Whiting C/6  


EPK                            9%
Gillespie borate           10%
Nepheline syenite        50%
Flint                             7%
Wollastonite                15%
Lithium carbonate       9%
Soda ash                      10%
Titanium dioxide         5%
Black iron oxide          6%

 12 - without cooling cycle.

18C - with cooling cycle.

18 - Jade Green C 5/6


G200                           38.1%

Barium Carbonate       19%

EPK                            9.6%

Flint                             9.5%

Gillespie Borate          9.5%

Zinc Oxide                  9.4%

Copper Carbonate       4.9%

 18 - without cooling cycle.


  1. Great experiments. I have tested many of these glazes with a different schedule. Basically a similar heating cycle but the cooling was done dthe following way: fast to 1800 then up to 2000 at 50/hr.
    I have results posted on
    Also look for results on Coleman teadust with same schedule. Send me an email if you want further details.

  2. Interesting! thanks for sharing these!

  3. You should give John Post credit for his recipes on this page. I have been to his site and it looks like you have benefited greatly from his recipes.

  4. I have not visited John's page but if he is the source of some of these recipes then he is due credit for them. Thank you, John Post, if you derived some of these glazes.

  5. Thank you for sharing your recipes. I'm a high school senior and we're doing research on different glaze variations for Cone 6. I need all the help that I can get because we are doing our own Cone 6 high fire glaze. I'm just hoping that my experiment comes out just as good as these. The glazes are beautiful and I look forward to trying some of these recipes out.

  6. Jaynie, remember glazing to get the effect you want means not only the formula, but the application (thickness, ect), the clay underneath, the firing schedule and other factors. Make lots of pieces so you get lots of practice so you can learn to control the process. Best of experiences to you. Terry

  7. Terry, do you think that various slips (particularly white) would show through many of these glazes? Im particularly curious about the Tomato red, Waterfall Brown 72, 122 Transparent - T12 C/6 Reddish Brown, and 145 - Satin Matt Cone 6 Lt. Green.

    Also, thank you so much for the effort and time youve dedicated into making these test tiles. They are wonderful!

  8. Looks like most all these glazes run. If fired to true cone 6, probably need to add some kaolin or alumina.

  9. Most of the runs come from double dipping the tiles. So you are correct to suggest stiffening with kaolin or alumina. However, with single dip, there was no running with most of these glazes,

  10. I recently spoke to Pete Pinnell about this very glaze (the glaze is usually referred to as Pete's Tomato Red #13, after him). Pete is the professor at University of Nebraska at Lincoln. I thought I'd share his comments on this particular glaze:

    This glaze performs best at a true cone 6 or a hot cone 6. The key to developing good color is to hold at one temperature on the cool down (in the range of 1800° to 1600°F) for 1 to 3 hours to allow the crystals to develop. The hotter the hold temp, the more deep burgundy red. The cooler the temp, the closer to orange red color. Do not confuse this with a slow cool down. Pick a temp, cool normally until you hit that temp, and then stay there for 1 to 3 hours, after which you'd resume cooling down at a normal rate.

  11. Thanks, Anne. As you might note above, I have done a slower cooling rate down from 1800 to 1300 @150/hour. I will try the hold technique and report back when I have some results.

  12. Hola por favor me podrías traducir: Gillespie Borate, Wollastonita, Flint,
    Nepheline sienita, muchas gracias.