Firing clay in an SC2

[Veebee]

Another thread intrigued me, and as I suddenly have a few questions I thought I would un-hijack that thread and make one of my own! OK, questions.......
a) can I fire small (say, focal bead sized..) pieces of clay in my SC2?
b) can I then glaze and fire the glaze in my SC2?

my thinking is that glaze is, well, basically glass? And the SC2 is hot enough to slump and fuse..... so from a logical point of view, well in my head anyway, you should be able to biscuit fire and glaze fire too? I am thinking (thank you Zeldazog) only earthenware would bicuit well enough, but if anyone knows if I could do stoneware that would be helpful. 

Any thoughts most gratefully accepted!
Thank you 

[Zeldazog]

Quick (ish) answer, my eyes are droopy 

Can't remember what an SC2 goes to, is it 1000deg C?... but here goes:

Earthenware (The most common being terracotta) full fires at around 1000 - 1050 deg C.  (not fixed, depends on particular clay, and the ceramicists themselves!)  It's not vitreous (waterproof).

You can get different coloured earthenware - I used a white, which was lovely putty type texture, just a light cream but ideally it fires up to 1050 - 1100 C - but you don't have to fire that high.

All bisque (biscuit) firing is done to the same - some will say bisque to 1000, others say 900-950 - in a way it does not matter, you're simply usually taking it to a stage that you can handle it without breaking as easily as dried unfired clay does.  A low firing, means that it will still absorb final glazes.

Stoneware, is bisque fired to the SAME temperature.  But needs to be fired higher to vitrify - waterproof. 

Normal "grey" stoneware, which is grey out the bag, but fires to a browny/grey/buff (STONE!) colour at 1260, at biscuit fires to a cacky light buff pink colour. 

You can get other colours in stoneware too.

Terracotta earthenware to bisque/biscuit goes to a not so nice as full fired sort of pinky browny terracotta colour.  Not the rich deep colour you associate with the name!  Another 100 degrees and you get the nice colour.

You can get glazes that fire to different temperatures.  You get them specifically for the types of clay bodies, so a stoneware glaze will take the higher temperatures.  An earthenware glaze will melt and run off the pot.

You can get special low fire glazes, particularly lustres, which fire right down at 800 deg C.

**Biscuit fired earthenware and biscuit fired stoneware are very similar.  Neither are waterproof or vitrified, neither have "matured" to full colour or strength.  But stoneware to 950 is probably same strength as earthenware to same temperature.  It's the higher firing that adds strength.

So, in theory, you could do stoneware, but only to bisque! 

And if you tried a specific stoneware glaze on it, and then didn't take it to stoneware temperature (1260), the glaze wouldn't work.

But there is no reason I can think of why you can't put earthenware glazes onto stoneware clay body.  You're right, glazes are glassy, and lots of other variants to adjust the melting temperatures, the flow properties, the sheen, and of course the colour.

Any particular reason you want to work with stoneware, Vicki?


Ok, will probably re-read this tomorrow and it won't make sense!

[Veebee]

Wow  Thanks! I know that stoneware is much more chip resistant than earthenware, and that you can still get a good range of colour glazes for it, however I wasn't aware of the temperature issue  ( I used to work in a shop that sold "china" , so we had to learn some stuff!)
Now I'm thinking I could do the low fire, add my glazes, let them dry and take them to a place in town I know has a clay kiln and hire a bit of space.
There is an amazing amount of info here, thank you so much Dawn!

[Zeldazog]

Wow  Thanks! I know that stoneware is much more chip resistant than earthenware,

There is an amazing amount of info here, thank you so much Dawn!

Generally it is - because of the higher firing...

At least doing my degree has some use!

[helenfc]

you guys have just got my ceramic imagination fired now too!! This forum should come with an addiction warning!! 

[julieHB]

Well, I say, another useful piece of information there, Dawn - thanks a lot!! 

[Veebee]

you guys have just got my ceramic imagination fired now too!! This forum should come with an addiction warning!! 

You're not wrong there 

Well, I say, another useful piece of information there, Dawn - thanks a lot!! 

I couldn't agree more!