Control of Brown Stain in Sugar Pine with Sodium Azide

Treatment of sugar pine (Pinus Lambertiana Dougl.) with buffered sodium azide dip will control enzymatic brown stain. The control of brown stain and the degrade caused by it can result in a savings of $15 to $20 per thousand to the sawmill owner. The best dip found to control brown stain enzyme for a two-week period for a cost of cents per thousand is as follows: 0.5 lb. sodium azide, 3-4 lb. borax, 2-3 lb. soda ash, and 100 gal. water. In addition, 3-5 lbs. of sodium pentachlorophenate may be added if blue stain or surface molds are a problem. However, if ethyl-mercury phosphate is used to control blue stain, then the azide level can be reduced by 50 percent. Using sodium azide to control brown stain makes it possible to more effectively use a dry kiln. This is because by using the dip one can start the kiln at higher temperatures and higher wet-bulb readings and thus dry the lumber quicker without fear of degrade caused by brown stain. In order to use the dip most effectively, the lumber must be treated as soon as it comes off the headsaw. One should also try not to keep the logs for any length of time on the log yard unless some precautions are taken to prevent staining at this point. This same method has proven to be just as effective in controlling brown stain in Idaho white pine (Pinus monticola Dougl.)

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