Wedge blocks in dimension of 5 x 7 to 8 x 155 cm3 were cut from indigeneous scots pine pitprops. Each of wedge block pairs were numbered and half of them were placed as the test blocks between the steel arches and the strata in a hard coal pit. Controls in laboratory and test wedge blocks in the mine were then sawn into 20 by 20 by 300 mm standard test sticks. Impact bending, static bending and MOE and specific gravity were determined to evaluate the natural durability of timber support against biodeterioration on the test sticks. Strength and specific gravity losses were calculated as a percentage of control values. Furthermore, relationships between residual strength values and losses in specific gravity were statistically evaluated. At the end of exposure period of 2.5 months, decreases in impact bending strength of scots pine wedge blocks were found 46.19%, in static bending strength 28.21% and in MOE 19.54% while the loss of 4.36% in specific gravity was determined. Blue staining moulding and brown-rot were identified on the wedge blocks.

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