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Celia UK

Member Since 01 Jul 2012
Offline Last Active Today, 04:38 AM
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Topics I've Started

White Stoneware Low Fire Glaze Mistake - Pinging

02 October 2016 - 11:58 AM

I've just taken a glaze firing out of the kiln - 1080oC (cone 04) transparent glaze on (mostly) a white earthenware clay. I can see that 2 pieces were in fact stoneware, which wasn't obvious after the bisque firing as my other pieces were white earthenware. The two stoneware bowls are pinging like mad and I can see the linear glaze cracks going round the bowls. The glaze can be pretty forgiving at higher temperatures and I'm wondering if these pieces might 'work' if refired to the clay's maturity temperature, or will the glaze fit always be a problem?

Glaze Application - Cracks

16 August 2016 - 04:11 PM

I have just poured the inside of a stoneware cylinder (test piece bisqued to 1000oC) with a transparent glaze that crawled horribly in a previous batch. This is a commercially mixed dipping glaze - very reliable by all accounts! Following advice here and elsewhere I let it stand and drew the excess water off the top. The glaze is now like pouring cream consistency. 100ml weighs 153g. I've poured the inside - about 3 seconds. As it dried the glaze cracked - see photo. What does this indicate? Can I just finger-sand it and dip the outside or am I destined for more disappointment?
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Substitute For Lead Bisilicate

07 July 2016 - 03:01 AM

I have a low fire transparent glaze recipe that makes a nice glossy glaze with a good colour response to various oxides. It has crazed slightly and would be even better for me if that didn't happen.
I know the lead bisilicate helps with the colour response but am not sure about sticking with this as my 'go to' recipe because of the lead.
This is for use on a smooth, white earthenware, sometimes just as a transparent over underglazes or oxide washes, but also as a base with oxide/stain additions.

Can anyone suggest a possible substitute? And if it helps with crazing that would be even better! I know I'll have to re-test, but a starting point would be helpful.
The recipe is -
Lead bisilicate 65
Whiting 10
Potash feldspar 15
China clay 10

Bisque Firing ?temperature Reached

19 December 2015 - 04:41 AM

Good morning all! Just opened my small electric kiln after a bisque firing. It was programmed - 100oC per hr to 600oC then 200oC per hour to 1000oC. I had 03 04 05 cones in a pack (really needed 04-05-06 but had this one to hand) on the bottom shelf and an 04 mini bar in the kiln sitter.

The temperature was rising as expected early on, but slowed down at the upper end, so overall took about 10 hrs. No error message on the programmer.

The work appears bisqued, but none of the cones, nor the minibar have changed in the slightest!
Some small test pieces were glazed (Once fire) on one 1/2 with a low fire transparent (matures at 06-05) which looks fine.

Any suggestions as to what is happening here?

Is there anything I need to consider when glazing these pieces - all will be transparent, shiny glaze.Attached File  image.jpg   96.43KB   2 downloadsAttached File  image.jpg   194.13KB   1 downloads