Same glaze/body. One fired flawless, the other dimpled, pinholes. Why?

Tuesday 22nd January 2019

The difference is a slow-cool firing. Both mugs are Plainsman M340 and have a black engobe inside and partway down on the outside. Both were dip-glazed with the GA6-B amber transparent and fired to cone 6. The one on the right was fired using the PLC6DS drop-and-hold schedule. That eliminated any blisters, but some pinholes remained. The one on the left was fired using the C6DHSC slow-cool schedule. That differs in one way: It cools at 150F/hr from 2100F to 1400F (as opposed to a free-fall). It is amazing how much this improves the brilliance and surface quality (not fully indicated by this photo, the mug on the left is much better).

Pages that reference this post in the Digitalfire Reference Database:

GA6-B - Alberta Slip Cone 6 Amber Base 2, Glaze Pinholes, Pitting, Cone 6 Drop-and-Soak Firing Schedule, Plainsman Cone 6 Slow Cool (Reactive glazes)

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