What Makes the Lumber Blue?

The Southern Pine Council has created an informative brochure about blue stained lumber. The brochure includes a helpful FAQ section as well.

What makes the lumber blue?

Blue stain is a common cause for the discoloration of lumber. Certain dark-colored microscopic fungi cause a bluish or grayish discoloration in the sapwood of the tree. However, not all blue stains are blue. Common stain shades can be blue to bluish black or gray to brown. Sometimes, the stain coloration in lumber may appear as red, yellow, orange, or purple.

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