Mmm, don't think 0q fibers are possible. (fiber-q(crops) depend on planted seed-q, and seeds are capped at a minimum of 1q.) But if anyone can proof me wrong ... please do.
----
Mmm, depending on Caveclay and Feldspar having a survival softcap (could not find anything saying 'yes' or 'no'). Boneclay could be pushed down to 4q. -> (4q-kiln, instead of 8q, or 5q with grey clay.)
- But, a 4q versus 5q kiln will only seems to make a difference if the unburned item q is a multiple of 1.5 (so for 3,6,9,etc.)