Porcelain firing

[Hairy Potter]

Hi,
Does anyone know if porcelain pieces can be fired straight to high firing temperature? I wonder if I can skip bisque firing as they are Xmas ornaments which don't need to be decorated or glazed.
Thanks,
Hairy Potter

[Cuckoos Nest]

You can 'once fire' to high temperature, providing you take the first firing stage (up to 600 deg C) as slowly as you would if you were doing a bisque firing.

Also you should leave the bungs out until it has passed 600 deg as this is the point where all molecular bound water is released.

Once past the slow rise to 600degs you can take it to whatever temperature you like.

Hope this helps. We often once fire to stoneware temp.

[C Hupfield Ceramics]

I used to bisque-fire before glazing and then refiring to stoneware temp, but I've recently started to once-fire a lot of my work as it still does the same job and is a suitable process for the type of work I make.

I'm sure I have once-fired porcelain up to stoneware temp before, but be careful of it deforming. Cuckoo's Nest has given a good word of advice, take the temp up slowly initially.

Good luck!

[toppotter]

Sure why not,

Sure why not, I agree just go upto 600C as bisque then as fast as you like. I did a firing like this a little while ago as I wasn't glazing I let the porcelain touch and took it to 1260. The touching pieces were a little fused together, but easily pullled apart luckily, So I would also suggest avoid them touching.

[Hairy Potter]

I used to bisque-fire before glazing and then refiring to stoneware temp, but I've recently started to once-fire a lot of my work as it still does the same job and is a suitable process for the type of work I make.

I'm sure I have once-fired porcelain up to stoneware temp before, but be careful of it deforming. Cuckoo's Nest has given a good word of advice, take the temp up slowly initially.

Good luck!

Yes, the tealight light holder did deform a little but it's acceptable. Thanks!

[Hairy Potter]

You can 'once fire' to high temperature, providing you take the first firing stage (up to 600 deg C) as slowly as you would if you were doing a bisque firing.

Also you should leave the bungs out until it has passed 600 deg as this is the point where all molecular bound water is released.

Once past the slow rise to 600degs you can take it to whatever temperature you like.

Hope this helps. We often once fire to stoneware temp.

Yes, it worked except for the tealight holder is slightly deformed. I think it is more to do with the design of the tealight holder. All the other christmas decorations are fine. Thanks!

[Hairy Potter]

Sure why not, I agree just go upto 600C as bisque then as fast as you like. I did a firing like this a little while ago as I wasn't glazing I let the porcelain touch and took it to 1260. The touching pieces were a little fused together, but easily pullled apart luckily, So I would also suggest avoid them touching.

It's a good tip. Thanks for that.

[C Hupfield Ceramics]

Glad it worked, thanks for letting us know!

To prevent pieces from deforming you could try using layers of thick folded fibre glass paper to support the edges of the piece, and to stop it slumping or moving during the firing. Or even kiln props if suitable.

** But be sure to wear gloves, a mask and goggles when handling fibre glass sheets

[toppotter]

You could also place them in silica/silver sand

You could also place them in silica/silver sand in a stoneware container to stop them deforming!

[gz.]

You might have problems with raw glazing if the glaze doesn't have much clay content (which you can see if it settles very quickly after stirring)
and the glaze might not fit the body