My last 2 campfirings yielded very different results. I decided it might be fun to bust up a pretty budlight platinum bottle - very blue- add some borax and see if I could get it to melt.
Welllllll... it melted, a little, in chunks. Fused some. But, the mule team borax melted in a nice puddle in one of the pots. Glaze, actually. But, the pots cracked completely and fell apart. No good.
So, I decided that maybe if I wedged (mixed for you nonpotters) some borax into the clay, it might help it to melt at a lower temp- this clay is very sandy and kind of short (cracky) so improving that would be good, but it wasn't as much my motivation as trying to get the pots to crack less in the firing.
I'm pleased that mixing in the borax actually did improve the workability of the wet clay, which was a pleasant unexpected bonus. Too much borax actually made it too sticky and wimpy, so there is a limit.
The last firing I did yielded some really beautiful orange pots with only a couple of cracks in the rim, and I was pretty aggressive in shoving them into the coals. I preheated the pots for about an hour at the edge of the fire, and then just shoved them under the logs. They weren't even buried in coals, so I'm wondering if there was a temp. difference which caused the cracks. I am, however, pretty pleased with the results.
My next plan is to mix some salt along with the borax into the clay and see what happens. Stay tuned. Camp starts next week!