My experience with ash glazes

Hello everyone!

A few months ago, I wrote about ash glazes. Recently, I have had some good results in this area and wanted to share the latest developments with you.

Introduction

Ash glazes are glazes that contain plant ash. They have been used for thousands of years and were probably developed after potters noticed a glassy layer on the surface of wood-fired pieces. As the wood burns, ash settles on the pieces, melts and fuses into a natural glaze. Over time, potters began deliberately adding ash to their usual glaze compositions, developing a wide range of colours and effects.

My experience

I fire a gas kiln in reduction to cone 6. Ash glazes are traditionally fired at much higher temperatures, so my first challenge was to investigate which raw materials would melt at lower temperatures.

I made a tile with several hollows and placed each material in its own hollow.

The feldspar usually paired with ash in glazes did not melt, but albite, a sodium-rich feldspar, gave a good result.

Albite and ash

The next step was to make a table of increasing and decreasing proportions of albite and ash.

…and so on, until I reached a sample containing 80% ash and 20% albite. The most interesting results came from a composition of 50% albite and 50% ash by weight. I used unwashed palm-leaf ash.

I collect the fallen dry leaves in the studio garden and
burn them slowly in a barbecue so that all the charcoal
turns to ash.

The result

Once I had chosen the proportions, I tried two application methods on
several pieces: spraying and dipping.

This was the result of dipping:

Here is the result of spraying:

I found the spray-applied result
the most interesting. The piece developed a yellowish tone where the
glaze was thinner and bluish tones where it was thicker.

Making ash glazes for cone 6 is not only possible; it can also produce
very surprising results. I am still at an early stage of the
research, but I am already achieving very satisfying results.

Until the next post!