Do grog additions always produce better drying performance?

Friday 24th January 2014

This DFAC test for insight-live.com/glossary/170">drying performance compares a typical white stoneware body (left) and the same body with 10% added 50-80 mesh molochite grog. The character of the crack changes somewhat, but otherwise, there is no improvement. While the grog addition reduces drying shrinkage here by 0.5-0.75% it also cuts dry strength (as a result, the crack is jagged, not a clean line). The grog vents water to the surface better, notice the soluble salts do not concentrate as much. Notice another issue: The jagged edges of the disk, it is more difficult to cut a clean line in the plastic clay.

Pages that reference this post in the Digitalfire Reference Library:

Molochite, DFAC Drying Factor, Drying Ceramics Without Cracks, Clay cracking often happens because of uneven drying, not lack of grog, Drying Performance, Drying Shrinkage, Cracking of Clays During Drying

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.