Friday, 27 September 2013

Bad firing

Well, it comes with the territory - getting used to disappointment. I'd really hoped for a lot from this glaze firing, but ended up disappointed. I included a few pieces made from the keuper red clay that I posted previously, alongside a load of Jen's porcelain favours and decorations. I'd also popped in a couple of the soup bowls with the hare design. These had been thrown in a white stoneware and then decorated with brown slip.
Anyway, the keuper red ware all bloated really badly - rendering it unsaleable. The white stoneware bowl decorated with brown slip fired ok, but the brown slip vanished! Did it run? I really don't know - I know that it's meant to be a semi transparent slip, but to completely disappear? These hare bowls were therefore not as I'd wished and I really wouldn't want to sell them.
I guess , from what I've read, that the keuper red bloated because it was over fired. I was told that it was ok up to stoneware temperatures even though it's labelled as an earthenware clay. Clearly not the case. I'm happy to fire to lower temperatures, but the only issue is that Jen makes porcelain ware that needs firing to higher temperatures, so sharing a firing is more sensible. I'm waiting for advice from potclays at the moment.
It really is disappointing. You just think you're making progress and then you feel like you're taking steps backwards.
I still have a lot to learn.

1 comment:

  1. This happened to me when I used Spanish clay, it was too high in iron and just bloated and buckled at 1107 which is what I take my Spencroft's clay up to.