\flhite Speck ln Douglas Fir

Bv H. L. Brown, General Superintendent \ilest Coast Bureau of Lumber Grades and Inspection

One of the most stubborn misconceptions among' lum,ber users-that the structural value of a piece of Douglas fir lumber is diminislied by the presence of white speck-has recently been exploded by a report from the Forest Products Laboratory of the U. S. Departrnent of Agriculture.

This is of far-reaching importance in the construction industry because in the past there has been a tender-rcy among' some building inspectors to refuse boards and dimension with white speck in the honest belief that the characteristic was dangerous decay.

At the instigation of A. A. Kayser, Bureau district supervisor in the Los Angeles area, the Forest Products Lab- oratory examined representative samples of lumber having this characteristic, and reported favorably on its use.

Summarized, the Laboratory report stated that: l. The durability of the pieces of Douglas fir containing rvhite speck would be no lower than heartwood free of white speck; their durability would be considerably greater than sapwood free of white speck.

2. If proper construction conditions prevail, a piece of sheathing, roof or sub-floor with white speck will have the same lasting quality as a neighboring piec.e rvithout white speck

3. The occurrance of white speck in Douglas fir could be expected to have no effect upon the subsequent durabilitv of the rvood.

4. The fungus Fomes pini, which produces the white speck in Douglas fir, dies when the lumber is dried so that it would not spread to neighboring pieces. If, horvever, the wood is used in a green condition and kept green it might spread.

By lvay of comment on the report it may be stated that it is impossible to keep lumber green, and that any lumber u'hich could be kept green might deteriorate. The warm dry climate of California guarantees that all decay action stops once the lumber is in the structure.

White speck is not a characteristic which indicates that the lumber has come from a dead tree. It is a characteristic found chiefly in mature, growing trees in certain areas. White speck occurs near the outside of the tree, where the knots are fewest, and such pieces consequently have a correspondingly higher value.

Since the structural value of the lumber is not impaired, the grading rules allow it in the No. 2, No. 3 and No. 4 grades in respective proportions.