Frits vs. raw materials in glazes: It is not just about the chemistry

Tuesday 17th September 2019

I have done alot of work recently comparing the sourcing of fluxing oxides from frits vs. raw materials. The differences are often incredible. The oxides MgO and CaO normally come from materials that melt high. But common frits that source them melt low. The chemistry in the two cone 6 glazes (comparing on this melt flow tester) are the same. But Y4 sources the KNaO from Ferro Frit 3110 instead of feldspar and alot of the MgO from Ferro Frit 3249 instead of talc. Y4 would flow even more but also has 10% calcined alumina! Sourcing Al2O3 from such a refractory material should make it melt less than sourcing it from kaolin, but the frits overcome even that to create this amazing fluidity in a matte glaze. The lesson: All glazes have a chemistry, but that cannot be taken in isolation from the materials that source it.

Pages that reference this post in the Digitalfire Reference Library:

Frit, Glaze Chemistry

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