So these glazes were my second attempt at iridescent surfaces. I tried some copper, upped the manganese in several glazes, and also tried granular manganese, granular magnetite, and granular ilmenite. The Fake Mashiko turned out really nice, not at all iridescent, but nice.
One thing to note is the all of the tiles on the left were from firing #38, which was a small test gas kiln. It wasn’t a very good firing to say the least. The tiles on the right were from firing #40, which was an extremely long, extremely hot firing. The schedule was something like 4 hours between cone 7-8, then about 5 hours between 9-10, an hour to cone 11, and another 2 hour soak around cone 12. Pretty extreme for a gas kiln, I think. On the other hand, that’s nothing compared to some Anagama firing schedules.
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!
Dolomite 5 Whiting 5 F4 Feldspar 65 Epk 5 Silica 20 Cobalt Carb 5 Red Iron 24 H20 65
Dolomite 5 Whiting 5 Custer 65 EPK 5 Silica 20 Cobalt 5 Red Iron 8
Dolomite 3.6 Whiting 3.7 F4 48 EPK 9.6 Silica 35 Cobalt 5 Red Iron 8
Dolomite 4.7 Whiting 4.7 F4 61 EPK 5.4 Silica 24.1 Cobalt Carb 5 Red Iron 8
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!
In an efferot to further explore the different variations of Iron Oxide, Ilmenite, and Rutile – I’ve run a series of tests substituting Red Iron Oxide, for other oxides available in my lab. It was a pretty good series, although on some of the oxides, I overshot the ideal % and on a few I think it could be more.
Notice the 12% addition of Earthenware clays in 8,9, and 10 produce some pretty nice Celadon glazes!
Here’s an interesting glaze inspired by a locally abundant material – dead palm fronds. Every week throughout South Florida the streets fill up with piles of dead vegetation from people pruning their trees and plants. With a 12 month growing cycle, they’re EVERYWHERE.
To utilize this stuff, I started by collecting about a half of a pickup truck’s worth of dead palm fronds. Collecting all of this stuff took about 10 minutes, and I didn’t have to go very far. I then setup a perforated burn barrel with a grated floor. I burned down everything, and collected the ash in a tray under the barrel. Once I collected the ash, I added it all to a 5 gallon bucket and ‘washed’ it, by dumping out the top layer of chunks and oily looking stuff. I gave it 24 hours, and came back out and stirred it, and repeated for the next few days. Fin ally, I poured the mix through a 40 mesh sieve into a bisque drying platter and let the stuff dry out. After that I crushed it into a powder and pushed it through an 80m sieve. Quite a bit of work, but a truly unique material.
Given that the soil here in Florida has so much Silica by virtue of all the sand it contains, I had the thought that its be likely that palm tree ash would have a much higher % of silica than say, hardwood ash. I haven’t had it tested for the side-by-side chemical composition, but my initial tests seem very promising. My next step is to dredge up some clay-like muck from the canal across the street, and mix in calcined seashells for good measure. If the canal silt doesn’t do the trick, I’ll try some clay/silt from the Intracoastal waterway (A brackish salt/freshwater channel that runs parallel to the ocean, inter-connected by inlets and canals – which ultimately keeps South Florida from turning back into a swamp!)
Nontheless, the 3 tiles on the left were soda fired. The 2 on the right were Reduction fired to cone 10/11. The clays from left to right are; Studio Reclaim (A bastard mix of everything), B-Mix, 550 Porcelain, Studio Mix, Porcelain. The recipe is as follows: