Tuesday, 26 March 2013

Another Kiln/Glaze Firing

Oh boy! I fired another load the other week and it's still got rim issues. I did put lots of test strips in, from scraps of slab that i'd played around with, to see how my black slip and various oxides were coming out with this glaze..... and they all came out perfect. There was no glaze coming of of sharp ragged edges or on any of the edges... yet all the other thrown and slab pieces i made had bits come off. They look more like they've been nibbled by a mouse than my earlier ones where it was small flakes. My rounded forms fared better but around small lumps for ears etc i can see the glaze has lifted and wants to pop off! I'm taking from my test strips that it's not so likely a 'fit' issue, but possibly more a temp/ramp thing. The glaze on some rims seems thin and a bit matt. I tried firing this glaze a bit harder and faster (which I read could solve any shivering) and it seems a bit better than last time. I had the turn up from 0ºc to max in 5 hours and the whole firing was about 7 and a half hours. Mini bar 03. I'm now going to ask around a few potters locally, i have 3 firings worth to examine and compare, so they have something to go on. Although i know most will say to bisc higher!!.. i explain that 900ºC is the way to go with this lead based earthenware glaze and they look at me like I'm nuts!!.. but I know better (well, actually Doug Fitch and Matt Grimmitt know better! and they make this stuff). Anyway, the joys of learning something new! I know I'm nearly there, i just need to nail it down and know in my own mind what is happening. meanwhile the ideas just pile up. I shall resume my throwing practice next week too. If nothing else it gives me things to test the glaze on! Which also made me wonder if there was something in my thrown pieces that caused the glaze issues, compression etc, but even pieces i built from slab have the nibbled glaze edges.... so why were the slab test strips so perfect???? AAAARRRRRHHHHHH.

'nibbled' rim!!!
These were fine, i'd messed around with some oxides on these.
I liked this little head, but the glaze looks like it will eventually pop off around one ear.


  1. The tests were fine and the pots not because that is the way of clay !

    Are you particularly attached to your glaze. There are some really nice unleaded glazes out in the world. Ron Philbeck has a great one.

  2. Darn that glaze pop off!! Pots look great man. I just sent you an email...finally! Have I sent you my glaze recipes? Let me know if you need them.

  3. Thanks guys... 'the way of clay', indeed!
    Hey Ron, i don't have the recipes, be nice to get them.
    I'm fairly sure the glaze and the clay are fine. Matt's proven it and has even glazed and fired one of my pots with it. It's totally something I'm doing/not doing. I know it's nothing major... am i getting the glaze on thick enough? are my temps out? this is when i wish i had a bit more clay education and knowledge... but i guess that's what I'm doing now!... the hard way.