Cone-7 Glazes I Use in Soda-Firing
This page is devoted to the glazes I currently use in soda-firing. At the Appalachian Center for Craft we did blackware bonfiring, pitfiring, cone-04 oxidation, cone-6 oxidation, cone-10 reduction, midrange and highfire salt and soda-firing, wood-firing, and wood-salt firing. I’ve fired my work in all of those processes, but through the last 18 of my 24-year career at the Craft Center, I soda-fired my work to cone-6 and occasionally to cone-10. We mixed all our own claybodies, and I was using a Warren Mackenzie buff stoneware body that gave good results. I stuck to a limited range of cone-6 glazes, mostly recipes from Tennessee potter and former Vanderbilt faculty Susan Demay. Here in North Carolina, using Starworks Star White-6 clay, I was less satisfied with the results I achieved in cone-6 soda-firing. The unsatisfactory results were probably due to changes in raw materials over time, a constant struggle for potters everywhere.
Susan Demay uses cone-6 glazes, but oxidation glaze-fires to cone-8 and the glazes look great. I decided to boost my firing temperature to a high cone-7, both for the glaze results and the soda effect on exposes clay. Star White-6 would be over-vitrified at that temperature, so I’ve been blending three parts Star White-6 to one part Star Okeewemee-10 in my pugmill, producing a claybody that vitrifies properly at cone-7/8 and gives the color I want on the bare clay. I am happy with the results, and all of these glazes do better at cone-7/8.
Below you will find a brief gallery of images for each glaze. Each images has a caption providing comments about the glaze and soda effects on the particular pot. In each gallery, the images represent the variety of surface effects I have seen with that glaze in my firings, and as you will see, the appearance of each glaze often varies widely. Variations depend on many things, including thickness of the glaze coat, how much soda deposits on the glaze (dependent on how much saturated soda ash solution I charge and where the pot is in the kiln in relation to the firebox), kiln atmosphere, duration of firing, maturation temperature in that part of the kiln, and outside temperature and humidity. Many potters shy away from glazes that are so unpredictable. I’ve gone in the opposite direction. In the 1970s and early 80s I was a production potter at Railroad Stoneware, my studio in Blue Lake, California, supplying kitchenware and tableware for gourmet kitchen stores. That market demanded consistent glaze results throughout the kiln in every firing. I had that down, but it became manufacturing and I got bored. I started losing my love of clay, and I don’t ever want to experience that again. I’d much rather have the uncertainty, where every kiln unloading brings some disappointments along with wonderful surprises.
I often have at least a cone variation between top and bottom of the kiln, and that contributes to the range of results from these glazes. Also, as compared to conventional oxidation and reduction firing, glaze results are less predictable in soda-firing due to the wide variation in soda deposition throughout the kiln. Many potters who like atmospheric glaze effects prefer salt-firing, which gives greater consistency and evenness of salt deposition. I do soda-firing because I celebrate the variety and asymmetry in soda deposition.
If you are interested in trying some of the glazes, click here for a downloadable PDF of all the recipes. Mix small batches and test, test, test. The recipe amounts given will mostly fill a five-gallon bucket once mixed with water, but you can recalculate for whatever batch-size you want. Divide by ten for a batch a little less than a half gallon, appropriate for serious testing.
Click on any image to enlarge, and then in the enlargement, click on the little square icon in the upper right for greater magnification to view surface details.
Dark Blue – modified from Diane Pancioli recipe
A reliable semi-gloss clear dark blue, almost a cobalt, but not too garish. I shied away from blue glazes for a long time, but I like this one in soda-firing. It’s as close as I’m willing to get to the classic “mother-in-law blue.”
Dark Blue – Recipe
Minspar – 2870
Flint – 2260
EPK – 1600
Whiting – 1330
Wollastonite – 870
3195 – 600
3110 – 350
Neph Sy – 120
Total – 10,000
Plus:
Cobalt Carb – 200
Bentonite – 200
Rutile – 180
RIO – 105
Copper Carb – 90
Keen Green – a recipe from Susan Demay, with the Zircopax left out.
A medium-dark blue-green that gives a variety of results, mostly good. Very similar to popular oribe glazes. Like many oribes, it occasionally precipitates smoky copper oxide on the surface, which is not unattractive but also not food-safe. Where the soda deposits heavily, the glaze turns a brilliant turquoise blue. It can also flash to copper red or pink in areas. It is wonderfully unpredictable, as the images reveal.
Keen Green – Recipe
Potash Spar – 4600
Flint – 1880
Gerstley Borate – 1360
Whiting – 810
Dolomite – 600
EPK – 250
Total – 9500
Plus:
Bentonite – 100
Copper Carb – 663
Rutile – 250
Klinesville Gold – from Susan Demay
A reliable mustard yellow, sometimes with the slightest hint of green. Very consistent, and like most glazes, goes transparent where the soda hits it heavily.
Klinesville Gold – Recipe
Neph Sye – 4545
Whiting – 1669
Redart – 1129
Wollastonite – 500
Total – 7843
Plus:
Manganese Dioxide – 410
RIO – 590
Zircopax – 1039
Lau Luster – from Britt Cone-6
A shino that goes from matt brown or orange-brown where protected from soda, to glossy gray-white where it receives more soda deposition.
Lau Luster – Recipe
Neph Sy – 6200
EPK – 2400
Soda Ash – 800
3134 – 600
Whiting – 200
Total – 10,200
Plus:
Zircopax – 200
RIO – 100
Olive – from Diane Pancioli (she calls this glaze “Amber”)
As soon as I tested this glaze, I decide to call it olive rather than amber. It gives a nice variety of effects, as the images show. With enough soda, it becomes a lovely variegated celadon. With less soda, it is partially opaque and nicely mottled. It’s lovely either way.
Olive – Recipe
Redart – 3900
Neph Sy – 1800
Whiting – 1500
Wollastonite – 900
3134 – 400
EPK – 300
Dolomite – 200
Flint – 100
Total – 9100
Bentonite – 200
Pinnell Blue-Green – Pete Pinnell
A bright strontium blue-green matt which often goes semi-matt or semi-gloss depending on firing temperature and amount of soda deposition. It occasionally flashes to red, which can be lovely. It is prone to copper oxide precipitation on the surface when applied thickly, as indicated in several of the images, and that surface is not food-safe.
Pinnell Blue-Green – Recipe
Neph Sye – 6000
Strontium Carb – 2000
OM4 Ball Clay – 1000
Flint – 900
Lithium Carb – 100
Total – 10,000
Plus:
Titanium Dioxide – 533
Copper Carb – 500
Raw Sienna – from MC6G
A lovely variegated yellow that goes to yellow-brown and red-brown and occasionally with heavy soda deposition, almost black. Reliably unpredictable and rarely a disappointment.
Raw Sienna – Recipe
Wollastonite – 2800
EPK – 2800
3195 – 2300
Flint – 1700
Neph Sye – 400
Total – 10,000
Plus:
Rutile – 600
RIO – 600
Slate Blue – modified from MC6G Variegated Slate Blue
A semi-matt light slate blue that goes to a lovely darker variegated blue where it receives more soda deposition.
Slate Blue – Recipe
EPK – 2400
Wollastonite – 2030
Flint – 1940
3195 – 1400
Minspar 1230
Whiting – 570
Neph Sy – 280
3110 – 150
Total – 10,000
Plus:
Rutile – 420
Copper Carb – 210
Cobalt Carb – 200
RIO – 45
Smoky Blue – (was Bright Sky Blue from MC6G)
Gives a variegated medium-dark blue that sometimes goes dark blue-black matt on the surface, but often also gives a dark, semi-gloss transparent navy-blue. Widely differing results, mostly good.
Smoky Blue – Recipe
Custer – 2000
3134 – 2000
EPK – 2000
Flint – 1850
Talc – 1150
Wollastonite – 1000
Total – 10,000
Plus:
Rutile – 300
Cobalt Carb – 100
RIO – 50
Spearmint – from MC6G
This glaze gives a distinct light spearmint green. When first tested, my response was “meh.” But with the higher firing temperatures the glaze is giving me some stellar results and I plan to use it a lot more. I will add more images as I fire the pots.
Spearmint – Recipe
Wollastonite – 2800
EPK – 2800
3195 – 2300
Flint – 1700
Neph Sy – 400
Total – 10,000
Plus:
Copper Carb – 400
Rutile – 400
Van Gilder Kaki – from Britt Cone-6
A lovely saturated-iron kaki that varies widely in tone dependent on the amount of soda on the surface, as indicated in the photos. As is the case with temmoku glazes, heavy soda deposition can cause it to turn to a lovely olive celadon, especially on the high spots where the glaze coat is thinner.
Van Gilder Kaki – Recipe
Minspar – 4770
Flint – 1160
Talc – 1720
Bone Ash – 1530
EPK – 410
3124 – 410
Total – 10,000
Plus:
RIO – 1170
Bentonite – 200
Waterfall Brown – from MC6G
The well-known cone-6 temmoku from MC6G – very reliable and makes an excellent brown liner. Heavier soda deposition makes the glaze go clear on the high spots while it remains brown in the recesses. That works out great with the relief patterns on my pots. As mentioned with the previous glaze, fairly heavy salt or soda deposition will dilute the glaze and cause it to go to a lovely olive celadon, especially on the high spots.
Waterfall Brown – Recipe
3134 – 3350
3195 – 2600
Flint – 2350
OM-4 – 1700
Total – 10,000
Plus:
RIO – 1250
Rutile – 100
White Liner – MC6G Clear Liner with 10% Zircopax added. A very reliable gloss white glaze that makes an excellent white liner or pure white exterior glaze if you like the classic “appliance white.” I use this glaze inside my beer steins so you can clearly see the color of the beer.
White Liner – Recipe
Custer – 2000
3134 – 2000
EPK – 2000
Flint 1900
Wollastonite – 1500
Talc – 600
Plus:
Total – 10,000
Zircopax – 1000
Wood Ash – common traditional ash glaze
This classic ash glaze is as simple as it can possibly be. The Redart clay tends to give it a slight greenish cast. The glaze is intended to run in order to get the familiar ash-glaze rivulets of color, but apply thinly or it will run right off the pot. Note that this glaze uses unwashed ash, which produces a very caustic glaze-mix. Wear nitrile gloves when handling the glaze, plus a face shield when mixing the batch and when glazing. The “Canopic Jars” in the Current/Recent Work gallery feature this glaze soda-fired to cone-10, and the “Post Industrial Reliquary” in the same gallery features this glaze reduction fired to cone-10.
Wood Ash – Recipe
Sifted, unwashed fireplace ash – 5000
Redart – 5000
Total – 10,000