Saturday, 16 July 2011

Cone 6 Test Results

Below are the results from my first batch of Cone 6 tests. I collected a number of glaze recipes, alot from this site and from other sources. The 17 glazes I picked were used mostly in combinations of two, one base glaze and another over the top.
The 17 glazes used; Chris Harris Tenmoku, Licorice, Nutmeg (revised version), Waxy White, Floating Blue, Floating Red, Variegated Blue, Water Blue, Water Green, E C Wide Base Blue Matt, Speckled, Chrome Tin Red, Jen's Juicy Fruit (no colourant), Zinc Semi Matt Light Blue, Green Matt, Val Cushing Green Ash, Hannah's Fake Ash. I purposely chose a selection of matt, gloss and semi gloss glazes. The clay i used is a white earthenware that matures at 1180 deg c. My supplier who also processes the clay, assured me it would be fine for Cone 6.
As this my first time to really test a variety of glazes, I will tell you how I went about it, so that you can see how I achieved my results AND so that those who have more experience can comment / advise on what I can change in the future order to get better results.
Firing Info - I have a small, manual electric kiln, approx 40 x 40 cm. I used three kiln shelves, two large cones (6) one on the top and one on middle shelf. Cone on top shelf was touching toes nicely and middle cone malfunctioned as it lent on a test tilie when falling (silly me). I set my temp controller to 1220 deg c to allow for a soak at Cone 6.  I peeked in the kiln at the cone when pyro read 1200 dec c and cone had just started to bend. Fell within in the next 20 mins and kiln automatically shut off at 1220 deg c. Also, at approx 1020 deg c, I turned the kiln down in order to slow down the end of the firing to try to achieve about 65 deg c per/hr. Total firing time was 9 hours, which perhaps is a little slow? Pls let me know. I did not do a controlled cool as I had intended to do. My daughter was not feeling well that night so going out to the kiln to do this was not an option later in the evening. But at least I have tests now with a natural cool and next time I can do a controlled cool and will have a comparison. I don't know if it counts for anything but I read the temp inside the kiln the next morning and worked out that from the time the kiln shut off to the time I read the temp in the morning, the temp would have dropped at approx 93 deg c per hour (naturally, with all bungs in).
Observations - I feel that perhaps my bottom shelf may have underfired a little. Some of my test tiles looked a little matt that should have been glossier. I had a few blister/bubbles with a couple of glazes too. My nutmeg glaze turned out semi matt when i expected a gloss? Someone may like to enlighten me with respect to Nutmeg. Licorice seemed to give me overall dependable and nice results when used with other glazes. I had spread evenly the tiles so not to have all the same bases on the same shelf in case of a temp variation in the kiln. Perhaps some of my glazes where a little thin. I still have a list of other combinations I didn't get around to trying here.
Anyway, I will let you be the judge. Please let me know your thoughts as this is the best way for me/us to learn.

A - Chris Harris Tenmoku only
B - CHT then Waxy White
C - CHT then Zinc Semi Matt Blue
D - CHT then Zinc Semi Matt Blue then Hannah's Fake Ash
E - CHT then Water Blue
F - CHT then Floating Red
G - CHT then V C Green Ash
H - CHT then Chrome Tin Red (has little flecks of red that are hard to see) 

I - CHT then Variegated Slate Blue
J - CHT then EC Wide Base Matt Blue then Hannah's Fake Ash
K - CHT then Juicy Fruit
L - CHT then Green Matt

A - Licorice only
B - Licorice then Chrome Tin Red
C - Licorice then Waxy White
D - Licorice then Nutmeg

E - Licorice then Green Matt
F - Lic then Water Green
G - Lic then Var Slate Blue
H - Lic then Floating Red

I - Lic then Floating Blue
J - Lic then C Harr Tenmoku
K - Lic then Zinc Semi Matt Blue
L - Lic then Speckled

A - Waxy White only (slightly green due to copper floating around in kiln)
B - WW then Water Green
C - WW then Green Matt
D - WW then Floating Blue

E - WW then C H Tenmoku
F - WW then Licorice
G - WW then Zinc Semi Matt Blue
H - WW then Water Blue

I - WW then Nutmeg
J - WW then V C Green Ash
K - WW then Hannahs Fake Ash
L - WW then Chrome Tin Red

A - Nutmeg only
B - Nutmeg then Speckled
C - Nutmeg then Floating Blue
D - Nutmeg then Var Slate Blue then Hannah's Fake Ash

E - Nutmeg then Licorice
F - Nutmeg then Chrome Tin Red
G - Nutmeg then Var Slate Blue
H - Nutmeg then Floating Red

I - Nutmeg then Waxy White
J - Nutmeg then Jens Juicy Fruit
K - Nutmeg then Green Matt
L - Nutmeg then C H Tenmoku

A - Water Blue
B - Water Green (crawling?)
C - E C Wide Firing Base Matt (Blue) Sure its not supposed to do this.
D - Floating Blue
E - Jen's Juicy Fruit (no colourant)

A - Variegated Slate Blue
B - Same as above
C - Floating Red
D - Floating Red then Licorice
E - Floating Red then C H Tenmoku

A - Green Matt
B - Green Matt then Waxy White
C - Green Matt then Licorice
D - Green Matt then V C Green Ash

A - Chrome Tin Red
B - Chrome Tin Red then Hannah's Fake Ash
C - Zinc Semi Matt Blue
D - Zinc semi Matt Blue then Licorice
E - Speckled (nice Matt)
F - Speckled then Licorice (very nice, almost like a woodfired look i think. Close up next)

F - Two examples of 'Speckled' with 'Licorice' over top

A - Speckled over a Copper & Iron Engobe/Slip
B - Jen's Juicy Fruit over a Copper & Iron Engobe
C - Tenmoku over a Chrome Engobe
D - Floating Red over a Chrome Engobe
E - Nutmeg over a Iron Engobe
F - Variegated Slate Blue over Iron Engobe

Thanks... if you have any questions, please let me know. Jan


  1. Nice glaze tests. I use the slate blue and the nutmeg. When i use the computer controls to slow cool these look very different . The slat blue is more of a washed jeans look and the nutmeg is browner and richer. If I just let the kiln turn off my glazes look much like yours. I do like the slate blue with the faster cooling and will fire a load each way.

  2. Hi Steve, I would like to have the ability to do a control cool with my kiln but only have the manual controller. Since these tests, I have tried turning the kiln back on at 900 deg c and holding for about an hr, with some better results. Also holding at 1200 for at least half an hr too. I would be interested to see some of your results if you have any pics? Are you a member of 'Cone 6 Midfire Potters'? Perhaps that is how you came across my blog. If not, have a look. Great website.

  3. Hi Jan!

    Love Love the licorice/speckled combo! Would you share the speckled recipe or maybe it has another name that I would recognize? Thanks for sharing your tests.


    1. Here is the recipe for 'Speckled' Cone 6

      Gerstley Borate 59 grams
      Talc 41
      Rutile 18
      Notes from where I obtained the recipe (Ceramic Arts Daily) say that its pretty over a white glaze.