Preferably, however, the chamber is slightly leaky in both directions so that a pressure barrier, which builds up within the kiln as it generates reducing gases, prevents {HEAD ~ an oxidizing atmosphere} from entering {TAIL ~ the kiln chamber} or rapid atmosphere exchange 
from entering
Preferably , however , the chamber is slightly leaky in both directions so that a pressure barrier , which builds up within the kiln as it generates reducing gases , prevents { HEAD ~ an oxidizing atmosphere } from entering { TAIL ~ the kiln chamber } or rapid atmosphere exchange
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH