Fire fiberclay in a well ventilated kiln Dont Panic ...
There will be smoke.
How to fire Fiber Clay
Fiber clay is easy to fire as it is very forgiving, EXCEPT! there will be smoke and bad smells up to 900 degrees F.
I suggest you fire in a well ventilated space, leave the lid propped open a couple inches and leave the bottom peephole open. The idea is to allow the fiber to burn out (oxygen is needed for this). Fire like this until the smoke stops and then close the lid. At some point your pieces will be black, this is normal. The carbon will burn off as it reacts with the oxygen to burn. Panicking and turning off the kiln will not help.
If you have the Sheepdog brand fiber clay you will fire it to cone 04. You must do this in a well-ventilated kiln hopefully with a envirovent. Then glaze with any low-fire glaze from Duncan or Mayco and fire to cone 06. Of course in a greenware firing pieces can touch.
Magic clay should be bisqued to 06-04 the glazed with a midrange glaze from Amaco, Coyote or Mayco (and Duncan)and fire to cone 5-6.