New pot kiln advice?

[MaxChavez]

Hi,
Just got my own kiln(manual, electric.) I've taken a couple classes at a local studio, and my mom has done pottery for years, but this is the first time firing solo.

My main question is stacking for bisque firing. Can I really just stack everything(bone dry) in there all willy nilly(exaggerating, of course) and let it rip? Like, put a large piece on its side and it won't warp(only talking bisque, at the moment.)

Also, any general tips for candling or ramp up for a manual kiln sitter?

Thanks!

 

[NaoTK]

For most pots that can fit into a standard electric kiln, yes you can stack willy nilly and touching. If the pot is very large and on its side it may warp or crack because the clay will shrink slightly. You also don't want things directly against the elements.
5 degrees/min is a good safe ramp upper limit. you should candle for 6 hours at 180F or longer if its thick

 

[MaxChavez]

For most pots that can fit into a standard electric kiln, yes you can stack willy nilly and touching. If the pot is very large and on its side it may warp or crack because the clay will shrink slightly. You also don't want things directly against the elements.
5 degrees/min is a good safe ramp upper limit. you should candle for 6 hours at 180F or longer if its thick

Thank you, very helpful!

Also, loved seeing all your teaser posts leading up to the expo- I'll definitely make it to the next one. Incredible work!

 

[penumbra]

My mind will not allow me to stack willy nilly. I have a kiln load now for bisque firing 32 pots. I will carefully put one side inside another but keep inner pot from pressing on sides of outer pot. I know I could put more in there but any warping, particularly of the feet, is not acceptable to me.

 

[ForrestW]

Very exciting getting your own kiln! It seems intimidating at first but in reality its pretty simple unless you work with really thick pots or super thin. As Nao said, you can really load up the bisque load, I load mine like Russian dolls inside one another. Usually on their rim so they are not putting a lot of extra weight on the lower pots, but when needed I do nest them as well or fire rim to rim. When you said Manual are you referring to a kiln sitter, and knobs to turn up the elements? If so candling can be just turning on one element on low and leaving the lid cracked for a number of hours.

 

[MaxChavez]

Very exciting getting your own kiln! It seems intimidating at first but in reality its pretty simple unless you work with really thick pots or super thin. As Nao said, you can really load up the bisque load, I load mine like Russian dolls inside one another. Usually on their rim so they are not putting a lot of extra weight on the lower pots, but when needed I do nest them as well or fire rim to rim. When you said Manual are you referring to a kiln sitter, and knobs to turn up the elements? If so candling can be just turning on one element on low and leaving the lid cracked for a number of hours.

Thanks for the reply. My biggest concern is a large oval(18) that I think I might only fit vertically. I may get a bit more shrinkage drying, but not sure. We'll see! I suppose I could also just scrap it, as I learned quite a bit about keeping bottoms flat on larger pieces, and I'm not completely happy with it anyways.
Yes, manual cone based kiln sitter with dials per level.
Thanks again!

 

[ForrestW]

Thanks for the reply. My biggest concern is a large oval(18) that I think I might only fit vertically. I may get a bit more shrinkage drying, but not sure. We'll see! I suppose I could also just scrap it, as I learned quite a bit about keeping bottoms flat on larger pieces, and I'm not completely happy with it anyways.
Yes, manual cone based kiln sitter with dials per level.
Thanks again!

Those are a trickier to work with, but I would not fire an 18"oval on its side, I think you will get some warpage. If you think it will be small enough after the bisque to glaze fire it on its feet I would give it a try, but I would not recommend it as a habit. I have had that problem a few times and I fired large pots on a shelf at an angle so I had a little more space. If you are going to make some 16-18" pots you may want to slow cool them as well. The only way I know how on a manual kiln is to use the spy holes and put witness cones in those and when you hit your top temperature, start lowering the dials over the next 3-4 hours instead of letting it cut off with the cone sitter. (Your cone sitter will need set with a higher cone so it does not cut off). Good luck with your new kiln

 

[RonS]

My main question is stacking for bisque firing. Can I really just stack everything(bone dry) in there all willy nilly(exaggerating, of course) and let it rip? Like, put a large piece on its side and it won't warp(only talking bisque, at the moment.)

Yes you can. When I bisque in my 7cuft kiln it takes me 3 glaze firings to get it all done.

When bisque firing heavy loads I go up very slowly.

I know you have a manual kiln. I'd advise getting a pyrometer and thermocouple to estimate your temps

See Links Below for Amazon
thermocouple
pyrometer

Bisque ^06
Seg Ramp Temp Hold
1 250F 230F 30
2 200 1000
3 100 1100
4 180 1569
5 80 1854 10

My biggest concern is a large oval(18) that I think I might only fit vertically.

FWIW, the largest I ever fired on it's side was a 16" platter and It came out fine

 

[MaxChavez]

Yes you can. When I bisque in my 7cuft kiln it takes me 3 glaze firings to get it all done.

When bisque firing heavy loads I go up very slowly.

I know you have a manual kiln. I'd advise getting a pyrometer and thermocouple to estimate your temps

See Links Below for Amazon
thermocouple
pyrometer

Bisque ^06
Seg Ramp Temp Hold
1 250F 230F 30
2 200 1000
3 100 1100
4 180 1569
5 80 1854 10



FWIW, the largest I ever fired on it's side was a 16" platter and It came out fine

Thanks for the tips and links!

Would you mind explaining the ramp up table just a bit more? Also, do you include a prolonged candle period beforehand?
Thanks

 

[penumbra]

When I load my large kiln, 13 cu ft, the pieces are not yet completely dry. I run the kiln up to about 180F or a bit more and turn it off. Then I open the lid and have a fan blow across it. If the kiln is really packed I do this a couple of times. This way my pieces are assembled or made, dried and bisque fired within a week tops. I do a slow bisque that takes 12 hours and I don't open the kiln for 24+ hours.

 

[MaxChavez]

When I load my large kiln, 13 cu ft, the pieces are not yet completely dry. I run the kiln up to about 180F or a bit more and turn it off. Then I open the lid and have a fan blow across it. If the kiln is really packed I do this a couple of times. This way my pieces are assembled or made, dried and bisque fired within a week tops. I do a slow bisque that takes 12 hours and I don't open the kiln for 24+ hours.

Very interesting, thanks for sharing. Would you not worry about that with thicker(5/8-3/4") pieces? In drying salami, you worry about "case hardening" where the outside dries and seals moisture inside, creating a bunch of problems. Maybe that isn't the case since the gentle heat in a full kiln creates a steam drying environment of sorts?
I had previously only heard dry as slow as you can, but all info is good info!

 

[NaoTK]

In drying salami, you worry about "case hardening"

This is a great description, I will have to steal it. Pots can explode because you think the outside is dry but the inside is still moist. Depending on the clay you use it may or may not vent the inner moisture out to the dry surface quickly. Folks can weigh their pot over time to verify it has stopped venting moisture.

Pots go through phases as they dry...first the clay is wet and it changes shape as it shrinks and dries. You do not want to force dry a pot in this stage because it will shrink unevenly and crack. But once the pot has stopped shrinking and it is still moist but starting to change color, then you can force dry it. I sometimes put these pots in the sun or in front of fans.

 

[RonS]

Thanks for the tips and links!

Would you mind explaining the ramp up table just a bit more? Also, do you include a prolonged candle period beforehand?
Thanks

The ramp is how many degrees I go up per hour

Would you not worry about that with thicker(5/8-3/4") pieces?

When I load my kiln I know for a fact that they are dry, so no I do not candle.

Most of my work is 1/4" to 3/8" thick. If I were to go as thick as you mention, then yes, I would candle.

Maybe I need to rethink how thick I make bonsai pots.

 

[MaxChavez]

1st bisque fire success in the books yesterday! No explosions. Thanks all for your help and advice!

 

[MaxChavez]

First glaze fire in the books! Still lots to learn, especially regarding glaze thickness. But, all in all, happy for the first go. I like things pretty rough and earthy, obviously.
Will definitely try to slow the cool down and maybe reduce the sheen a bit on some glazes. Which definitely sounds like a pain manually, but after picking up the pyrometer , does seem doable. Some day I'll splurge for the programable control panel.
Thanks for stopping by!

 

[19Mateo83]

Awesome work!