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grayfree

temp for opening kiln?

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My new kiln takes a day and a bit to cool to 200C so slow in fact that a number of my glazes have changed significantly and some not for the better.. I haven't the recipe here but a blue/green has become so metallic and matte that I will have to play to get it where I want it or give it the flick.

Unless one of the readers of this post has any ideas.....taking plugs out and crash cooling at the top end?? What harm would this do to elements and bricks?

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I have no science behind this, but if you're crash cooling at the top end of your temp you're going to end up pulling in significantly cooler air through your peep holes - could possibly thermally shock hot elements and brick local to the peeps.  I do it because I already know I'll be working on my kilns continuously through the year, some home ceramicists might not ever touch their equipment until it breaks.

 

Sometimes you just gotta do what you gotta do.  I've been known to crash cool the student's work in a big gas kiln firing - just leave the damper and burner ports fully open and remove the spys.  Below maybe 500* I'll crack the door open and put on the blowers.  Usually this is only when we are on a time restriction, usually for critique.

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High Bridge Pottery

Joel Edmondson

Posted 06 March 2014 - 02:24 PM

You probably have a lot more pieces in a bisque firing to hold the heat in the kiln compared to the air in a glaze firing.

Great point, it all plays a roll in how fast the kiln cools. The scientific term is "thermal mass" for those who want to know in technical terms. The simple illustration is: two pots of water boiling on the stove covered. One has one quart of water, the other has 1 gallon of water; obviously the one gallon will take a lot longer to cool. Simple premise- but you get the point.

A cheap way to track temps on the low side of cooling (400F and under) is using an oven thermometer. Just stick it in a peep hole or under the lid. Can buy them most anywhere for $3-5 and most have a 3-5" probe.

Nerd

 

Note: Was just reading the technical specs on K-23 IFB. Very low thermal conductivity 0.17% @ 725F. Basically what that is saying is: at 725F the brick is storing little heat- everything else in the kiln however is.

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