WarmGlass.com

Hi,

I made a mold with ceramic fiber, using Hotline mold hardener. Searching through this site and others, I figured out that I first needed to fully dry the mold (heating at approx 175F for a few hours then air-dry). While the next step seems obvious for this rigidizer (firing at 1300F), I have not found any information on how long to fire the mold for. I assume that the rate of increase is not critical, but I have been wrong before

Any help would be much appreciated!

Lucie

I know of no reason not to fire as quickly as you like.

I fired it at 1300F for 30 min. When I opened the kiln this morning, the mold was still fairly soft (definitely not as hard as ceramic) and I would even say almost brittle. The Hotline rigidizer that I used was purchased in February and always kept at room temperature, so it should still be good. The mold was soaked in, then the excess squeezed out, so there should have been enough colloid particles in there.

What is next? Can I soak the same mold again, dry it and fire it again?

Lucie

i have always had to rigidise twice. do not expect the mold to be as tough as ceramic though. they will always be fragile. if you do not pick them up by the edges or bash them around , they are very long lasting. rosanna

Thanks Rosanna! That second firing did the trick.

Lucie