Thursday, August 12, 2010

Kiln Testing...what have I learned from this???

Kathy asked me this question....and the first answer is to NEVER, NEVER try to pry a piece of fused ceramic off a kiln shelf with a screwdriver.  I can now bend my thumb 45 degrees without splitting open the wound.  I'm hoping for 90 degress by the weekend.  It's healing quick.

But I realized I didn't have a clue what the first test showed me.  Pyrometric cones are not straight forward.  The point at which a cone bends depends not just on temperature, but ramping speed, and hold time.  So after studying the Orton website I choose the my cones. 

I'm specifically testing my kiln with a full ramp up to 1550.

Full ramp, no hold time
Full ramp, 30 minutes hold time

Full ramp, 1 hour hold

 So I expected to see the cones slumped, especially the ones that had lower set points.  And I expected to see the cones bend more as the hold time was extended.  What I didn't expect to see was no bend in the cones that didn't have a hold time.  I expected some type of bend.

What did I learn??  Well, my kiln is firing just fine.  It certainly isn't underfiring...which was my concern.  And something we already knew....short hold times don't give the kiln the chance to equilibrate and let the heat effect the metal.

No comments: