Fix lid seal if a bright red glow is visible around the seal when kiln is operating and/or excessive heat loss can be felt around seal.

1. Rub seal high points down with sandpaper until no more than 1/16 of an inch gap is found at any point along seal.
2. Check for unevenness in the gap that will cause an excessive heat loss.
3. Replace lid if it is excessively cracked or worn or has holes in it. Replace lid.