Glaze Recipe: Alison Thyra Grubb

My interest in lustre began when I visited the open studio of Fiona Duckett at Watergaw Ceramics in Scotland. Fiona has over 20 years’ experience with in-glaze lustre and she kindly shared her base glaze recipe with me, which I still use today. Throughout my degree I’ve been testing various additions of oxides in Fiona’s base glaze recipe and learning to refine the lustre-firing process.

I make my forms using white earthenware casting clay and bisque-fire them to 1180°C. After this, I apply glazes by either dipping or spraying, using a slightly thick application. I then fire the glazed pots in an electric kiln to 1020°C. Next, the glazes are fired for a second time in a gas kiln to cone 017. When the kiln reaches temperature, I close the flue leaving a 1-2 inch gap and reduce for 20 minutes. It is during this firing that a chemical reaction takes place and the metal oxides within the glazes will transform into metallic, iridescent lustres.

A single glaze result can appear different in each firing and one glaze may look different depending on which shelf it was on or how close it was to the flame. Lustre glazes can be quite unpredictable so I take notes during every firing to learn from my mistakes and recreate successful results.