So, kind of like a dancer who limits herself to only a few moves, I have been groping around for viable, sustainable and beautiful oilspot glazes that will work in my kiln. It is a tall order.
I have a couple of recipes that always work if applied correctly on porcelain. Examples:
I do not need a special firing schedule to get spots with these two glazes, I just need to go to 1280 degrees Celcius at 100 degrees per hour after 900 degrees. So that's handy, but I "need" more. I want to see and make all kinds of different spots - preferably on the same bowl!
A couple of potters have unknowingly been very helpful in this search. There is Australian potter Steve Harrison of http://tonightmyfingerssmellofgarlic.com . Another is American potter Matt Fiske, who has generously shared many interesting observations on his blog https://mattfiske.wordpress.com/ . One post that intrigued me was about him sourcing rhyolite and basalt from the wilderness in Utah. Sigh! I live in an urban environment and cannot easily source materials from around me. In fact, I would not know where to look or what to even look for! My supplier did not carry any volcanic ash when I asked, so I turned to Amazon, which as you know can source just about anything... Sure enough, they had 250 mesh pumice for use in dental cabinets. I got a small stash of that, and mixed up a glaze bucket according to Matt Fiske's research - 1 part basalt to 3 parts pumice. Assumed he meant by weight rather than volume. Gave up on sieving it. Looked in my notes and saw it is my 33rd attempt at a base glaze recipe, so took a deep breath and labelled it Oil33 (A/B/C/D). By the way, this glaze smells wonderful ;-) - just like my dentist's clinic.
The glaze did not adhere well to the porcelain test tile, so I mixed in 1 part gaolin, and added 6% RIO.
|Oil33 fired to 1250 degrees|
I was pleased to see I got spots at both 1250 and 1282 degrees Celcius. The small test cup I glazed also fired nicely - I think the glaze thickness accounts for the difference in appearance. The cup was glazed very thickly compared to the test tile. A few pinholes.
Next, I tested some variations, none of which I will pursue further.
|OIl33 + 3% titanium|
|OIl33 + 1% rutile|
Ahem. My children tell me I am never satisfied with anything. It is just that... I think... I just need to twist it a little... some sparkle is missing... it is lacking that "wow! factor.... So, I still am not finished with this Oil33 business. If I find that "wow" ingredient, I am not sure I will be posting it here. Got to leave you guessing.