|Monthly Tech-Tip |
Made using porcelain fired to cone 11+. This is a splendid demonstration of translucency. Without a back-light it is just a white slab. But the varying thickness in the porcelain determine the amount of light that passes at any given spot, thus producing the design.
Top: A thin porcelain tile with etched design. Bottom: The same tile with a back light. By Stephanie Osser.
"Émail ombrant" (French for “enamel shadow”) is a pottery-decorating technique developed in France in the 1840s (at the Rubelles factory by Baron A. du Tremblay). Designs were etched or stamped into the pottery and a transparent colored glaze, in this case green, was applied thickly enough to re-level the surface. The varying depths produce colour highlighting. The design appears shadowy, hence the name. Stephanie calls these plates “Girls on the March”, they were inspired by parents who supported their girls with dynamic signage at the Boston of “Women on the March” rally in 2017.
Standard porcelains used by potters and for the production of sanitary and table ware have surprisingly similar recipes. But their plasticities vary widely.
A highly sought-after property in porcelain, fired close enough to melting to take on the glass-like property of passing light. Translucency implies tendency to warp during firing.
Plainsman Polar Ice cone 6 translucent porcelain
Four Cone 6 (1200C) Casting/Throwing Porcelain Recipes (Grolleg and #6 Tile)
Four recipes that can be adjusted to work for casting or throwing/hand building (by adjusting the percentage of bentonite). The more you are willing to spend on the materials the more whiteness, translucency and plasticity you will achieve.