A wood based material may be formed having {HEAD ~ a permeability} which is {TAIL ~ at least 5 times that} of the untreated wood 
is
A wood based material may be formed having { HEAD ~ a permeability } which is { TAIL ~ at least 5 times that } of the untreated wood
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH