The back flat side of balls of 1916J and Q low fire glaze that melted into a dome shape after being fired to 1550F. They have been turned over to see the back side (the front side is still stained by volatilizing carbon). Clearly they have reached zero porosity and are beginning to melt, yet they have not adhered to the vitreous porcelain tile! This demonstrates the degree to which an engobe must melt to secure itself well to the underlying body.
Pages that reference this post in the Digitalfire Reference Database:
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 digitalfire.com.