Dusty bisque firing

[PottyMcPot]

Hi - I just opened my first solo bisque firing, terracotta and everything is in tact - tried the tumble stacking method - however, the pots are really dusty with fine terracotta powder. Is this normal or does it indicate something wrong with the firing? I only have a tiny Phoenix 13amp kiln: set it to 30% for an hour although everything was bone dry and had been in the sun all day. I then turned it up to 100% for 4 hours before the plug got hot and I felt I couldn't leave it longer. Going to get it hardwired before the next firing.

Any thoughts would be welcome.

Thx

 

[Callie Beller Diesel]

That’s normal, and it’s not your kiln. Some clays will do this more than others, and I seem to recall the earthenware I worked with waaay back in the day also seemed chalkier than usual after the bisque. Just give everything a rinse and let it dry before glazing. The dust isn’t good for you, and it’ll keep your glazes from applying properly. 

edited to add: not all clays will require this: some only need a wipe off with a damp sponge. Some don’t need it at all. Go with your own observations. 

[Min]

1 hour ago, PottyMcPot said:

set it to 30% for an hour although everything was bone dry and had been in the sun all day. I then turned it up to 100% for 4 hours before the plug got hot and I felt I couldn't leave it longer.

Going forward I would suggest putting some cones in so you can see what the kiln fired to. Just going by time alone isn't accurate enough, for glazes especially. It's good you are having someone look at the plug/wiring before doing another firing.

[PottyMcPot]

Thank you for your comments and I'm relieved you think the firing was probably good. I had ordered cones but was impatient for them to arrive! You can guess what happened: yes, they arrived during the firing! All set now to do my first glaze firing with cleaned and dusted pots and better wiring.

[neilestrick]

The rule for loading the kiln is to keep pots at least an inch away from the walls, at least on the walls with elements. This will prevent hot spots from  the pots being too close to the elements.