The termination of "full dimensional lumber" coincided with the World War  II 
years. In the San Diego, California area, saw mills stripped away the outer  
six or eight inches of wood to cut their lumber for the "heart" wood (with 
dense  or close growth rings) rich in concentrated sap. This wood was harder, 
resistant  to termites, and fire-resistant. But during the war years, wood became 
scarce  and milling procedures changed to maximize the wood from logs. The 
mills churned  out thousands of board feet of soft boards that were fine for 
short-term  construction jobs, but subject to termites and burned like dry Xmas 
trees. After  the war, the mills sent the rough cut wood back through the saws 
to create a  smoother surface for the retail market, which reduced the size of 
the lumber.  This means that a full-cut 2" X 4" inch board might actually 
measure 1 7/8" by 3  7/8," although the length was the same.
 
Ron May
Legacy 106, Inc.