I use a 30 gal. drum with 15 - 20 gal. of kiln dryed red oak and cherry. This has worked very well and routinly get 50 ppm on the soap test after one or two passes through the chips.
I have 2 lbs. of Thermax that i was going to use as a final polish but have not needed it.
On my next change-out would there be any benefit adding say 1 lbs. of the resin in a layer, in the middle or lower part of the sawdust?