Bisque firing

[RICHARD SE]

Hi all

i understand you can slow bisque fire within a couple of days after throwing. Can someone please tell me what firing settings/temperatures I need to set my electric kiln

regards richard 

[Hulk]

Hi Richard!

Please provide make and model of kiln, controller type (if any), type of clay, also general description of your pieces - as far as influencing your bisque, e.g. thick, thin, large, etc.

I'm using mid fire clays, hence bisque to about 04. My research indicates the rate of temperature climb should slow/pause at the "critical" ranges, see this thread:

https://community.ceramicartsdaily.org/topic/20132-slow-bisque-kiln-help

There are several links in the second post; "Critical Firing Temperatures" would be a good place to start:

https://community.ceramicartsdaily.org/topic/17903-critical-firing-temperatures

I like red and brown clays, hence significant pauses at "organic carbons burn off between these temperatures..." and "inorganic sulfides from lignite coal particles and iron disulfide burn off." 

Ramping right up at the start, as I'm running the load up to 200F the night before and leaving the kiln fan on all night; even in winter the kiln is still warm the next day.

 

 

[RICHARD SE]

Hi hulk

evenheat 3 cubic ft 

rampmaster controller 

stoneware clay white

at this moment I’m making test tiles 60 mmx35 mm 

thanks 

[Bill Kielb]

To give you a generic answer would mean to ask what kiln, what controller etc.....  Instead let me say this:

• Drying, within a couple days - the green clay that was thrown needs enough time to thoroughly dry out, often referred to as bone dry first.
• The purpose of bisque firing is to burn out all the hydrocarbons and impurities while sintering your ware so time and temp are important
• Sintered Clay is still very porous and will absorb your glaze consistently.
• One popular temperature to  bisque to would be cone 04 1945F
• The timeframe to fire is usually about 14 hours and does not exceed about 200 degrees per hour 
• An initial period of drying time below 212 F is usually included just to make sure your clay is thoroughly dry so a sudden release of steam does not crack your ware.

Having said all that we will need to know what kind of kiln you have. Below I have posted an 04 automatic cone fire schedule for you to see. If you have this control and pressed slow bisque  to 04 then this is the schedule it would run.

[Bill Kielb]

9 minutes ago, RICHARD SE said:

Hi hulk

evenheat 3 cubic ft 

rampmaster controller 

stoneware clay white

at this moment I’m making test tiles 60 mmx35 mm 

thanks 

Thanks,

The rampmaster has a slow bisque button and fires similar to that I mentioned above. The link to the ramp master manual is 

https://docs.wixstatic.com/ugd/3a9418_dc2236499ac84a71a2aaa5dab96eceba.pdf

they also have videos available on you tube 

[Hulk]

Test tiles, smart! White clay, also smart, less problems.

My kiln is manual, hence not much help on programming your controller. Good news is your results should be much more repeatable. Also good news, your kiln and controller are well documented.

Bisque load takes about ten hours for me (having run any water off the night before).

Take good notes, and have fun!

[Min]

If you are just firing test tiles, made from white clay and nothing else, then once the tiles are bone dry the firing can go quickly allowing that they are not stacked solid in the kiln. If you take a room temperature test tile (or pot) and put it against your cheek it shouldn't feel cool. If it does then you need to either let them dry longer outside the kiln or do a candle (preheat) in the kiln to dry them out. If the tiles are still damp then a candle of 200F an  hour up to 185F with a 2 hour hold should be adequate then I'ld just run the preprogrammed fast bisque program. 

[liambesaw]

On my bisques I usually candle for 4 hours with the lid cracked, I have found that even pieces on the slightly moist side of bone dry are fine like that.  If it's moist like in a leather stage I think I'd just wait a day or two.

[RICHARD SE]

3 hours ago, Min said:

If you are just firing test tiles, made from white clay and nothing else, then once the tiles are bone dry the firing can go quickly allowing that they are not stacked solid in the kiln. If you take a room temperature test tile (or pot) and put it against your cheek it shouldn't feel cool. If it does then you need to either let them dry longer outside the kiln or do a candle (preheat) in the kiln to dry them out. If the tiles are still damp then a candle of 200F an  hour up to 185F with a 2 hour hold should be adequate then I'ld just run the preprogrammed fast bisque program. 

Thanks very much 

[RICHARD SE]

3 hours ago, Min said:

If you are just firing test tiles, made from white clay and nothing else, then once the tiles are bone dry the firing can go quickly allowing that they are not stacked solid in the kiln. If you take a room temperature test tile (or pot) and put it against your cheek it shouldn't feel cool. If it does then you need to either let them dry longer outside the kiln or do a candle (preheat) in the kiln to dry them out. If the tiles are still damp then a candle of 200F an  hour up to 185F with a 2 hour hold should be adequate then I'ld just run the preprogrammed fast bisque program. 

Thank you min