A heavily grogged vitreous clay for functional? Redart and engobes make it possible

Tuesday 15th May 2018

This is L3118J, a chocolate brown burning super-plastic base clay (to which 25% coarse grog is added). The base matures at cone 6, yet the grog stabilizes the fired matrix enough that it stands up in the kiln at insight-live.com/glossary/125">cone 10R, firing to a dense vitreous product (its porosity of 4%, comes from the grog). Only 20% Redart clay provides both the color and the K2O flux (no feldspar is needed). There is a second factor that makes this clay functional: An engobe to smooth the surface under the glaze. These two mugs employ L3954N (on the inside applied at the leather hard stage), they enable the smooth surface needed for the glaze. The glaze is brown and blue colored versions of G2571A.

Pages that reference this post in the Digitalfire Reference Library:

Craft Crank sculpture clay is plastic and smooth: Yet it has this much grog! How is that possible?, A heavily grogged body: Yet throws surprisingly well, Engobe, Vitrification

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