Cone 012

[Hands On]

Hello 

2 questions 

I am using a kiln sitter and making small sculpture pieces in earthenware - keeping my cost down wondering when firing at cone 012 if the pieces will have much strength ? and if I choose to glaze cone 04 will there be any problems i should be aware of.

Thanks for any tips Foster

[Min]

I have seen quite big differences in the maturity cone for earthenware bodies in the UK. For the clay you are using what is the top cone (or firing temperature if a cone isn’t posted) for the clay? 

[Hands On]

Hello Thanks  Madeleine

The firing range is  temp is 1080  - 1180

 

 

[Denice]

You get some impurities that come to the surface of the glaze with that low of bisque.   White earthenware may not be that bad but red terracotta needs long C04 bisque it has lots of impurities.   You have C4 clay none of there temperatures you are firing  it to will work.   The pots will be very fragile and  leak,  if you want to keep working in the low fire range you need to buy a bag of low fire earthenware clay.     Denice

[Hands On]

Ok thanks 

When i bought this clay they said it was low fire earthenware,?

I am not making any thing to hold liquid just small sculpture pieces, but would still like the bisque to have some strength. perhaps I should then increase the bisque temp, 

[Min]

6 hours ago, Hands On said:

The firing range is  temp is 1080  - 1180

So at 1080C (approx cone 03) the clay will be less dense and mature than if fired to the upper temp of 1180C which is approx cone 5. The more mature a clay is the stonger it is. For what you are making it probably isn't critical to fire to 1180C but if you ever decide to make functional ware it would be a good idea to do fire to the clays maturity temp of 1180C.

Another point is the colour of the clay will in most likelihood change as you fire hotter. Below is an example of a local earthenware clay I can get fired to different temperatures.

[neilestrick]

If you're thinking about the lower firing being less expensive, the cost difference between 012 and 04 will be negligible. Fire to whatever cone gives you the look you want.

[Hands On]

Thank you Neil and Madeline good advice

I am amazed how the colours change,  there seems to be more brightness in the earthenware when fired lower.