I’ve been running glaze tests on Laguna’s WC-429, I contacted Laguna and was told by Jonathan Pacini that the COE figure (using their methods of testing) is 4.60 x 10 -6. My question is what is a reasonable expectation of a COE maximum figure for a clear glaze to fit this? My current low COE glazes are in the 5.7 area. When I shock tested them they appeared to survive on this clay without crazing but I'm not 100% sure since it's so hard to see crazing on a dark body.
Wondering if anybody has run tests comparing clay COE figures with glaze COE and come up with any data on a range where the glaze still fits. I know that glaze calc COE’s only get you so far and some glazes with a higher COE might fit whereas lower ones don’t always do due to the family of fluxes used but just asking in general terms here. Even glaze coe versus published clay coe figures would be helpful for me to determine a working range of figures.
(I asked Laguna for sample glaze recipes that would fit and their commercial MS 29 was suggested, I’m not using commercial glaze though so that was no help)
Any thoughts or insight? Thanks in advance for any help.
edit: I know I should run a series of tests from lower to higher coe's but am trying to find out if anyone knows of a window range? Trying to come up with a coe under 5 would be fun.