thomas rubino wrote:That's not a bad price for refractory. Way more than fireclay but should be more durable than the FC mix Your going to want to experiment. Try a small batch at 50/50 then try a batch at 70/30 I think a 50/50 mix might be to fragile in the feed tube but be fine in the burn tunnel and riser. The fireclay mix is known for wear issues in the feed tube (trying to push wood down) When casting a core you should be able to vary the amount of perlite, using a refractory heavy mix at the feed tube end and then add more perlite as you form the burn tunnel . The riser can be cast with a "fragile mix " heavy on perlite.
Glenn Herbert wrote:I would suggest making a richer refractory mix for the inner surfaces of the feed tube and burn tunnel, and surrounding that with a highly insulative mix.
Glenn Herbert wrote:The riser can be mostly perlite with just enough refractory to hold it together (make test bricks with various ratios).