An arm pit hair
For those of you that have fired or do fire a solid fuel kiln in reduction you will know that the width of a hair can make the difference between reduction and oxidation. Our kiln has fired at the same damper setting and fuel pressure tickedy boo for close to 300 glaze firings. The last few have started to not be killer. Sheila and I vacuumed the burners for spiders and earwigs, reset the air, inspected then with the door open etc, etc and still not the racer firings we had expected. We checked the damper and could see erosion of almost a half inch and just plain old wear and tear. We just replaced the damper so we hope to be back in the zone again.
Here is a pic of some of my tiles leaning against the rolls in the kiln. We find firing the flat ware including plates and platters on edge in the bisque firing has a much greater success rate. These tiles are two inches thick and heavy as sin.