Monday 22 August 2011

Matt ash glaze: unpredictable and intriguing!

It's been a nice, warm sunny day today..just a few clouds in the sky and no rain at all for a change! So it was a beautiful morning to open the kiln and end up smiling at some of the interesting pieces which came out.
Most of the pots I put in yesterday were glazed with the same oak-ash, matt glaze I used on the little sake cup last time. I put a few pots inside the saggar with a little charcoal and the rest on the top shelf so they would fire in an oxidised or neutral atmosphere.

I find this glaze really fascinating, as the finish seems to be affected by a number of different factors. As usual, glaze thickness is critical and I discovered that one brushed-on coat simply isn't enough..that piece came out rather dull and patchy in appearance with barely any yellow in the surface, almost all dark reds and browns. Brushmarks were also clearly visible in places. What was interesting though, is that some pieces ended up being quite similar in appearance even though one was fired in oxidation and the other in reduction in the saggar. Another critical factor seems to be heat work on the piece and whether they are directly exposed to the fumes from the charcoal in the saggar. The more heat and fumes, the darker the glaze seems to get, to the point where it turns quite black. Most pieces have a yellow-brown-black mottled appearance, but one espresso cup has a really deep red-purple hue and the yellow areas have hints of green in them too (please see the first photo below).

All in all, this glaze is fairly unpredictable, but in a good way..unlike some glazes where they are unpredictable and their revelation is invariably accompanied by a deep sigh of tragic disappointment. I'm pleased with most of the pieces I pulled from the kiln today, and I'm happy that this glaze recipe provides a wonderful starting point for further experiments. Next time I intend to try layering a satin-matt calcium glaze over this ash glaze and see what occurs..I can't wait!

Espresso cup with matt ash glaze. Reduction firing

Oil pourer with matt oak-ash glaze. Approx 3 inches tall
Oxidation firing

Vinegar shaker with matt oak-ash glaze. Approx 3 inches long.
Oxidation firing.

Bowl with matt oak-ash glaze. Approx 3 inches tall.
Oxidation firing.

Espresso cup with matt oak-ash glaze. Oxidation firing

No comments:

Post a Comment