Crash Cooling

[Mark C. 3,719]

Ok we all know not to cool a kiln  down to fast. I had some friends who cracked their advancer shelves by opening the damper to soon to cool off their downdraft 30 cubic foot kiln.

I alwaysa close the damper at cone 11 and let it sit for a few days until last Saturday.

You know when ceramics seems like its flowing along well than wam two X four in the head.

Last Saturday I was firing two glaze kilns (both gas) started them at 5.30 am. The 1st one went off at 4.30 pm and I closed it up as I have a thousand times before.

We get into a routine about these things or so we think.

Second kiln cone 11, 1/2 way down  at 5 PM -turn off 4 burners on right side and then the other 4 burners left side.

About 3 hours later I sat down on couch in living room and noticed the heat waves reflecting on my socks-I jumped up realizing the low sun was showing the heat waves into the living room meaning the damper never got shut down 3 hours ago. I raced out and shut the damper. The digital pyro showed the kiln dropped 1,000 degrees in that 3 hour period. I was off on a two day trip to SF in the am and for two days  thought about the worst-broken shelves cracked pots under oxidized glazes-you name it. I have never done this in 45 years-made a damper mistake.

I knew the cystals would not be there in the glazes 9they needs slow cooling to form) What else can happen to a 35 cubic kiln load of stuffed porcelain pots when its crashed cooled.

Last night when arriving from a 6 hour drive I opened the kiln to find all is well. The only thing so far noticed is my brown glaze is muddy and very brown not reddish. I have yet to unload it all so we shall see what else is astray .

Just when its all going so well-even the pros get it wrong now and again.Ceramics is most humbling at times

[oldlady 2,339]

oooohhhh mark................

[liambesaw 1,567]

I found a neat trick for iron reds the other day, I have an iron glaze that goes tomato red if I bisque it after glaze firing.  It is usually brown.  Gonna try it with my other iron glazes soon

[Mark C. 3,719]

If you use synthetic bone ash (if your recipe calls for bone ash) it will be way red.

[Babs 903]

yes got a borinhg green which is lovely refired to cone 03

good luck Mark, and nice observations form the couch!!!!

i guess you placed that couch so could be alerted of such things...licky the sun was shining on you!

[neilestrick 3,345]

You should only have problems with cracked ware and such if it gets too cold in the crash, like quartz inversion temps. Beyond that things should be fine. A refire of iron reds does wonders. @liambesaw if you slow down your cooling you should be able to get the reds without having to refire.

[Mark C. 3,719]

Yes my pots did not crash through quartz inversion so that was a great thing. I'm unloading kiln today at 3 pm-I already took a bunch of stuff from it to outlets.

This year was super for sales as Mothers day and graduation weekend at the collage where on two separate weekends-Often its the same weekend . So I made sales at a show at UC Davis far away for 3 days over mothers day and all outlets sold well that weekend as well as the next weekend  when the state collage has 2,600 graduates with parents mostly from out of town  visiting so sales again spike at the outlets.Checks will be rolling in and I had to restock 8 outlets as well again.

Edited May 24 by Mark C.