Stain-based black engobe is clean to use!

Thursday 22nd March 2018

Stains are fired, inert particles of a relatively large ultimate size. Unlike that, raw oxide powders, like iron or manganese, have much finer sizes and are thus extremely dirty to use. This plaster slab is being used to dewater these 15% black engobes for shrinkage testing. The slurry on the right has just been poured, the one on the left has just been peeled up (it was spread across almost the entire surface). Notice it has left no stain (the marks on the outer edge wash off easily). What does this mean? It means that using this engobe is much, much cleaner than using a body or slip colored using raw or burnt umber, iron, manganese or cobalt.

Pages that reference this post in the Digitalfire Reference Database:

Engobe, Stain

This post is one of thousands found in the Digitalfire Reference Database. Most are part of a timeline maintained by Tony Hansen. You can search that timeline on the home page of