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I just finished reading the thread on duraboard firing.

I applied the rigidized on all six sides; let it dry for two days; fired it to 1450. I opened the kiln this morning and the board is all blotchy. Charlie says if it's not white, flip it over and fire it again.

I flipped it over and the other side is all blotchy also.

Is this thing suppose to end up white or did I not put enough rigidizer on it?

Judy

Fire it again. It usually takes a couple of firings to clean it up.

Phil

Judy Schnabel wrote:I just finished reading the thread on duraboard firing.

I applied the rigidized on all six sides; let it dry for two days; fired it to 1450. I opened the kiln this morning and the board is all blotchy. Charlie says if it's not white, flip it over and fire it again.

I flipped it over and the other side is all blotchy also.

Is this thing suppose to end up white or did I not put enough rigidizer on it?

Judy

White means that the binders are burned out. Blotchy, not quite burned out.

The way I have always approached burnout is to fire to whatever temp you plan to use the board at. If you are a comber, go to 1700. If you fire at 1500, go there...

Thanks Phil & Bert,

I'll crank it up again.

Judy