|Monthly Tech-Tip |
The red underglaze on this low-fired bowl is not properly fluxed (melted), it does not adhere to the body (this is a commerial product). The bottom-most contour of this bowl is concave and the transparent overglaze, which is under some compression, has popped right off! This is a serious hazard on the inside of functional ware. Each stain has it own melting temperature, and the underglaze formulation using that stain must employ a mix that supplies sufficient fluxes. So test your underglazes (by firing without an overglaze), even if they are a commercial product.
A intensely pigmented and highly opaque brushing compound meant to be applied to leather hard pottery and covered with a transparent overglaze.