Plasma Tears of Delilah
Date: Spring 2022
Creator: Adrian Muller
Temperature: Cone 6
Atmosphere: Oxidation
Recipe:
Nepheline syenite 40%
Silica 30%
Whiting 20%
EPK 10%
Lithium carb. 10%
Plasma Slag 20%
Bentonite 2%
Notes:
Not sieved. Thinner application works well. May drip and bubble when applied thick. Beautiful variation and color where it pools.
Delilah is the nickname of the plasma cutter at the School of the Art Institute of Chicago. Dross – or slag – is the term for the droplets of molten pulverized metal that deposits along the cut lines of the sheet metal (usually ferrous steel) of varying thickness.
The droplets are chiseled off the material, torched once more, and pulverized into a fine ferrous soot. The powdered slag is a cocktail of metal oxides and other minerals that serve as a powerful colorant for this glaze.
Each batch of pulverized slag will likely be different depending on the sheet-metals used, as well as other factors like atmosphere and humidity which may affect the chemical compositions of the slag powder with time.
The glaze displays multiple properties. It is at once a dry matte yellow glaze, and a rich glossy black one. The characteristics of the glaze emerge in response to the clay body beneath, the texture, and curvature of the forms. The glaze breaks into the mottled and luminous yellow over edges and wide surfaces, and pools into deep glassy black.
Application is very critical for achieving the required glaze result. Due to the dense and varying nature of the powdered metal slag oxide, and also to the massive quantity in relation to the base recipe, the particles of the slag settle and suspend very differently throughout the glaze mix.
The glaze can be dipped, brushed, poured, or even spray, but for each of these techniques be mindful of the varying proportions of the glaze and suspended particles. For spraying, the glaze renders more brown, and misses some of the color-shifting properties. This is likely due to the heavier potent oxides in the slag settling at the bottom of the spray canister. The ratio of slag to the base glaze recipe can be altered freely up to 50%.
WARNING: This is a runny glaze! perhaps it is due to the fluxing property of some of the minerals in the pulverized slag. Rather than dry up the glaze with alumina, this recipe celebrates the mysterious properties that emerge when the glaze runs smoothly over the clay wares. Use a tray for firing, or use the glaze with specific geometry and wares in mind that will compliment and work with the properties of the glaze.
