Cooling rate drastically affects the appearance of this glaze

Saturday 23rd November 2019

This is the G2934Y satin insight-live.com/glossary/130">matte glaze recipe with Mason 6600 black stain (6%). The piece on the left was fired using the C6DHSC firing schedule (drop-and-hold at 2100F then 150F/hr to 1400F). The one on the right was fired using the PLC6DS schedule (drop-and-hold at 2100F then free-fall from there). The slow cool gives the glaze on the left time to crystallize, creating a stony matte. My kilns are generally lightly-loaded, so free-fall firings drop pretty rapidly, producing the effect on the right. This phenomena is a characteristic of high MgO glazes (ones having significant dolomite, talc, Ferro frit 3249). To get a surface between these extremes we make this glaze using a 20:80 blend of G2934 base (which fires even more matte on slow-cool) and G2926B glossy. In our typical fast-cool this mix produces the degree-of-matteness I like.

Pages that reference this post in the Digitalfire Reference Library:

G2934Y - Cone 6 Magnesia Matte Low LOI Version, What Determines a Glaze's Firing Temperature?, A gunmetal glaze I have wanted for decades!, Matte Glaze, Firing Schedule

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.