Blue Stain in Sprinkled Log Decks and Lumber Piles of Ponderosa Pine

Ponderosa pine (Pinus ponderosa Laws.) logs decked under various water-spray conditions during summer in central Oregon soon changed appearance. Sapwood of log ends sprayed with clean river water darkened within a few weeks; white resinous bloom and green slime appeared later. Logs sprayed with warmer, turbid pond water were quickly covered with dark slime. Sapwood tended to be 10?F warmer than sprayed water. Intermittently sprinkled logs developed increasing amounts of blue stain from prolonged spray-off periods. Blue stain in logs amounted to <1 percent surfaced lumber tally if spray was continuous or brief and intermittent (6 min. on < 10 min. off); the longest sprayoff (34 min) cycle increased log stain to 3.6 percent. The amount of additional blare stain which developed in lumber close-piled outdoors for 4 weeks during November and December despite cool air temperatures, seemed unrelated to log sprinkling practices. Staining in lumber piles amounted to <2 percent of board footage. In some cases, more stain developed in lumber than in decked logs. Total downgrade by blue staining both logs and piled lumber was greatest in logs sprinkled the least (34 min. "spray-off" period); 5.7 percent downgrade and a loss of $11.75 per thousand board feet. No loss resulted when logs were sprayed 6 minutes on, 6 off, but absence of stain in that piled lumber probably occurred by chance. Less than half the stained surfaces lumber was actually downgraded, except if sprays were off 34 minutes.

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