Yesterday, I completed a cone 6 firing with mixed results.
The clay from the big tub, which tested at 1.5% absorption but looked shiny, slumped badly. I had been afraid of that. I conducted a line blend on this clay, and the absorption decreased with larger additions of nepheline syenite, so it wasn’t overfired in that respect. At this point, I’m assuming it needs alumina to stiffen it. I’ll add some kaolin and see how it performs. This clay contains a significant amount of sand. As I’m getting older, I’m trying to reduce the processing required for my clay bodies and didn’t processes it as fine as I normally do.
The good news is that the clay body I’m currently working with, which tested well for absorption, survived the firing with my lowest-expansion glaze. I still need to stress-test it, but so far, it’s promising. Now I just need to get the dang stuff to thicken enough to work without forming dry lumps. It’s taking forever!
I also tested two other glazes. One is my black glaze, which I hadn’t used in about four years. I rehydrated and sieved it, and it turned out beautifully. The black mug and the blue mug were made from a clay batch with 4.5% absorption (too high), but I loved their appearance. If they develop issues later, I can always discard them.
And last but not least, yet more test tiles. I had enough trimmings and throwaways to justify mixing up a reclaim batch. Plus the G200-EU addition which I don’t think is going to work. It absorbed a drop of water, so absorption is probably still high.
