Some advantages of fibre board:
- It is light weight making it easy to move.
- Fibre board has very good cooling characteristics as it doesn't hold the heat the same way a mullite shelf does.
- The board is fragile, but with care can last years.
- Fibre board shelves do not thermal shock as ceramic based shelves can.
Considerations for use:
- If it will be moved it needs hardening.
- It needs repeated sanding and hardening for a really smooth surface. Alternatively you can smooth on something like batt/kiln wash or alumina hydrate for each firing.
- It needs to be supported on kiln posts at 100 mm intervals.
You need to use dust masks when ever working with fibre board.
Some disadvantages of fibre board:
- The board can warp over time even when supported every 100 mm.
- The board will warp over time if placed on the kiln floor.
- The board needs to be thick - at least 25mm, thicker for larger kilns.
- It can't be scraped clean of batt/kiln wash.
- Ceramic fibre board is possibly not much cheaper than mullite shelves.