[DAY]

My "Magic Cooker" -aka L&L e28T- has 4 buttons for programs. Slow Bisque-Fast Bisque-Slow Glaze-Fast Glaze.
Other than dryness of greenware, is there a preference of speed? Or are the programs different for other reasons?
I bisque at Fast Glaze, to ^04, then fast glaze to ^5/6.
I always assumed that the bisque firing was just to burn out the nasties, (and water!), and make the clay mature enough to handle.

[bciskepottery]

I use Slow Bisque (^05) and Slow Glaze (^6), with 10 minute hold (both). For bisque, Slow gives more time for the nasties to burn out -- I use a lot of red iron bearing clays. Tried Fast Glaze once and did not like the results. Same kiln as yours. If your approach works for you and your clay body and glazes, then fire on. Still takes a long time to cool.

[TJR]

Day;
This might seem like a dumb question, but why are you using the glaze program to bisque?
I do not have a computerized kiln, but my bisque fire takes about 7 hours tops. Start on low for 2 hours, medium for one hour then switch all switches to high. All spy holes should be closed. I bisque at cone 07 or 06. I do not know why you are bisquing so high. This is costing you energy.
The function of bisquing is water of hydration- to drive off any chemical water, then the pots are permanent and ready for glazing.
Try out your bisque programs. Couldn't hurt.
TJR.

[Marcia Selsor]

When I am firing my raku paper clay large slabs I use a slow bisque to ^06. When I am firing dried porcelain I do a fast bisque to ^04 for stronger bisque when glazing.
Marcia

[meghanmuir]

DAY, on 15 August 2012 - 08:23 AM, said:

My "Magic Cooker" -aka L&L e28T- has 4 buttons for programs. Slow Bisque-Fast Bisque-Slow Glaze-Fast Glaze.
Other than dryness of greenware, is there a preference of speed? Or are the programs different for other reasons?
I bisque at Fast Glaze, to ^04, then fast glaze to ^5/6.
I always assumed that the bisque firing was just to burn out the nasties, (and water!), and make the clay mature enough to handle.

Unless I'm absolutely positive that everything is 100% dry, I always fire a slow bisque

[clay lover]

This question has been on my mind also .
I think I am firing much slower than necessary to get bisque to ^5, which is what my clay and glazes like.

If my ware is bone dry, how fast can I run a bisque?

I was trained by an uber conservative, but very experinced potter that had very few loses, and that really appeals to me, but I'm taking 12 hours to run a slow bisque.
I have a computer driven kiln and can put in any program I choose. I always go slow the first hour to 200*, what can I do to speed up things with out losing ware or having issues later in the glaze from failure to clean out the clay?

[RuthB]

I do my own program to 010.
You can find the factory firing profiles in your manual in appendix F, not A as it claims, unless they've corrected the typo.

My profile is more in line with the fast bisque, but it goes slow when it needs to dry the ware and burn out organics

Segment rate Temperatur
1 200 200 Hold until no moisture escapes the kiln. Check with mirror, if you're not sure. As long as you hold below the boiling point, it doesn't matter how fast or slow you get there.
2 150 600 I go slower than the slow program here because the first quartz inversion is around this temp and I've seen ware failure at this higher temp with faster firing, especially uneven or thicker work.
3 250 1000 This speed is between the slow and fast settings. This is a good temperature range to speed up the firing. Not much is happening to the clay,but organics continue to burn out.
4 150 1100 Slow through quartz inversion
5 200 1537 This is faster than both factory settings of 180. I've never had a problem, but slow down if you're concerned.
6 108 1700 Since cone melt is formulated for 108 degree temp rise per last hour, this rate gives a more accurate cone melt/temp rating.

I fire to ^010 because I've never had a reason to fire higher with my own ware or my students in 35+ years. It costs less and the ware is plenty sturdy. The slow firing burns out the organics without firing hotter. The ware is more absorbent at ^010; I mix the glazes thinner which I find better for layering glazes. It might take a bit of getting used to, but I prefer it to hotter firings. Bisque of a fully loaded kiln is approx 8 hours. YMMV.

Ruth

[neilestrick]

I always tell my customers to fire Fast Bisque and Slow Glaze. Both of those will give the same approximate firing time as firing a manual kiln at one hour on low, one hour on medium, then high. Slow Bisque is too slow for most pieces in that it wastes energy firing that slow. It's really best for large, thick pieces that must go that slow. Fast Glaze to cone 04 is only about 4 hours. Your glazes will look a lot better if you go with Slow Glaze, which is a little over 6 hours.

[Chris Campbell]

"I think I am firing much slower than necessary to get bisque to ^5, which is what my clay and glazes like."

Clay lover ...
I have to ask ... why are you bisque firing so high? What temp is your glaze fire?

[timbo_heff]

DAY, on 15 August 2012 - 09:23 AM, said:

My "Magic Cooker" -aka L&L e28T- has 4 buttons for programs. Slow Bisque-Fast Bisque-Slow Glaze-Fast Glaze.
Other than dryness of greenware, is there a preference of speed? Or are the programs different for other reasons?
I bisque at Fast Glaze, to ^04, then fast glaze to ^5/6.
I always assumed that the bisque firing was just to burn out the nasties, (and water!), and make the clay mature enough to handle.

It really depends on the clay. Some clays contain a lot of things that need to get burned out before sintering or else you can get bloating etc.... problems that may not even show up until the glaze fire.
I recommend slow bisque for that that reason. Seems an easy way to prevent issues.
For some clays is is good to hold for an hour or two just below sintering to get out even more of the organics if one is getting bloats.
Other clays that might be "cleaner" can be fine with a fast bisque.

[clay lover]

Chris, ask away, obviously that was written before the 2nd cup of coffee!!

I meant to say bisque to ^05, not ^5. way big diff, don't cha think?

[Chris Campbell]

So now you also know not to program the kiln before your second cup of coffee!!

[yedrow]

After getting the water out I bisque at 180/hr. I'm still probably freaked out from dealing with 10,000 pounds of blistering B mix. I like to be sure that all of the nasty stuff is out.

Joel.

[clay lover]

I agree about the 'freaking out' part, I am little OCD about some things, but I'm wondering if my 12 hour bisque is over kill? Can I be more efficient and still be safe?

[DAY]

TJR, on 15 August 2012 - 06:31 PM, said:

Day;
This might seem like a dumb question, but why are you using the glaze program to bisque?
I do not have a computerized kiln, but my bisque fire takes about 7 hours tops. Start on low for 2 hours, medium for one hour then switch all switches to high. All spy holes should be closed. I bisque at cone 07 or 06. I do not know why you are bisquing so high. This is costing you energy.
The function of bisquing is water of hydration- to drive off any chemical water, then the pots are permanent and ready for glazing.
Try out your bisque programs. Couldn't hurt.
TJR.

I use the fast glaze, because that is what I have used for two decades, to single fire Standard's 266, to cone 1 (2043 F). Force of habit! Yesterday's bisque took 6.46 hours to cone 04. ^04=1886F ^06=1823F. With that small a temperature difference, I doubt there is much difference in time or cost. And I treat my bisque rough, putting the slips on, sponged off. I will, however, try the Fast Bisque/Slow Glaze that Neil suggests.
In my 26 year old J230 I put the bottom switch on Low for a couple of hours- more or less, depending on other tasks and an aging brain! Then all go on low for "awhile", followed by all on Medium, for more "whiles", and finally all on High. I never timed it, but that old gal seems to fire fast, be it ^04 or ^5/6. And nothing ever blows up.

Here's a photo of Standard's 181 stoneware. Left to right, bisque, black velvet brushed on/sponged off, then glazed with Standard's Waxy White 1065.

Attached File(s)

•  3 181 mugs.jpg (99.12K)
  Number of downloads: 39

[Chris Campbell]

DAY ... Love your work ... Can you post a website or link to more images?

[DAY]

http://www.art-kiosk.com/25069

The leaves are old enough to vote. The "Contemporary Artifacts" are still gestating.