An interesting view of my most recent round of test glazes. Each Oil Spot variation was dipped in porcelain and red stoneware with the red stoneware tiles shown. The firing was: 10 hr oxidation to Cone 7, 2hr oxidation slow climb to Cone 8, 3 hr slow climb to cone 10, 1 hour oxidation hold @ cone 10. The results were pretty cool, and under magnification they had just the right amount of galactic goodness. The pictures were taken with a USB digital microscope! Magnification is about 30-40x
For the longest time I’ve wanted to try firing oil spot glazes, and after a bit of research it was pretty satisfying to make it happen. I decided to begin by concentrating on black, single glaze variations – the recipes of which came from a number of sources, mainly John Britt’s ebook and Complete Guide to High Fire glazes, a few from Michael Bailey’s Oriental Glazes, and a couple from Hopper’s The Ceramic Spectrum. The next step is to start zeroing in on some of the more spectacular variations and then start changing up the recipes and the firing schedules for maximum effect. Enjoy!
Taken in 2007 during my studies in Jingdezhen, China. This thrower uses the traditional gaolin china clay. I drew a picture of a large round vase with a small neck and then he proceeded to make exactly what I drew while also making the clay do some truly remarkable things!
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Here’s the newest round of slips for leather hard/stiff application. All but #7 will work for bone dry application. Not tested (yet) for bisque application. Fired to cone 10 flat in a hard reduction. Left side is super thick, right side is thinner. Clay body is a Hawthorn/Goldart/OM4 stoneware – nothing fancy.
#1 Greenware Slip: Grolleg Kaolin 40, OM4 Ball Clay 10, Custer 25, Silica 25
#2 Greenware Slip v.1: EPK 25, Grolleg 25, OM4 Ball Clay 10, Custer 25 Silica 25
#3 Bringle Slip: EPK 20, OM4 20, Neph. Sye. 25, Silica 30
#4 BS v.1: Grolleg 25, OM4 25, Neph. Sye. 25, Silica 25
#5 BS v.2: Grolleg 30, OM4 10, Neph Sye 20, Silica 20
#6 Coleman Clay: EPK 50, Silica 25, Custer 25, Frit 3110 5
#7 CC v.1: Grolleg 50, Silica 25, Custer 25, Frit 3110 5
#8 Porcelain Slip: Grolleg 30, OM4 8, Custer 30, Silica 30, Bentonite 2
The light is cheating these a little bit. #1,2, and 8 seem to be the whitest, with not much differentiating them. #1 seems to promote the best celadon blues, although timing is critical, because it cracked when applied to a bone dry tile. #2 seems to be a perfect middle ground in terms of versatility, cost, and whiteness. In my experience, the difference between a 50/50 grolleg/epk and a 100% grolleg clay body is negligible in cone 10 reduction. The case could be made that it really matters in oxidation – which is just now bringing to mind the need to test these in c6 oxidation.
My picks? For Whiteness:
EPK 25, Grolleg 25, OM4 10, Custer 25, Silica 25, 45cc Water, 5cc Darvan #7,
For Celadon Blue:
Grolleg 30, OM4 8, Custer 30, Silica 30, Bentonite 2, 50cc Water, 5cc Darvan #7