hardwood - grades and specs


Hardwood Grading School

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Interactive Alder Grading Pages

These pages will help determine the grade

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Hardwood Specifications

The following data was compiled from industry-recognized tests conducted by the U.S. Forest Products Laboratory:

  Western Alder Bigleaf Maple Western Red Oak Pacific Madrone Tanoak Oregon White Oak Golden Chestnut Northern Poplar Oregon Ash Sycamore California Black Walnut Western Birch
Machining 9 8 9 10 8 7 6 4 7 7 9 9
Resistance to Splitting 8 8 9 9 9 8 7 6 8 7 6 7
Joint Strength 9 8 8 8 9 9 7 5 7 6 6 8
Gluing 10 8 8 8 7 7 8 6 7 6 7 9
Sanding/Polishing 10 8 9 9 8 8 8 4 7 5 9 9
Finishing 10 8 9 6 8 7 8 4 8 5 8 8
Specific Gravity .41 .48 .57 .65 .66 .72 .46 .35 .55 .49 .55 .60
Weight Per Cubic Foot 28.7 33.6 39.8 45.4 46.1 50.3 32.2 24.5 38.4 34.3 38.4 32
Weight per MBF 2390 2850 3320 3785 3930 4190 2680 2040 3200 2850 3200 3250
Hardness 5 5 8 10 9 9 6 3 8 6 7 7
Shrinkage Volume (%) 12.6 11.6 9.7 17.4 14.9 13.4 13.2 12.4 13.2 14.1 12.8 11.5
Static Bending 6 7 6 6 10 6 7 4 9 7 9 8
Impact Bending 5 6 5 6 8 6 7 4 8 9 8 6
Compression 6 6 8 8 8 9 5 3 7 5 6 7
Dimensional Stability 8 8 9 5 7 8 7 5 7 6 9 8

Values obtained from consideration of USDA Forest Products Lab, Oregon State University Forest Research Lab, Pittsburgh Testing Lab and years of practical applications.

Machining - Average of 5 operations: Planing, shaping, turning, boring and mortising (High of 10).

Resistance To Splitting - Resistance to splitting from nail or screw (High of 10).

Joint Strength - Average of side and end grain screw holding ability measured in shear factor and converted for comparison (High of 10)

Gluing - Total Bond Strength (High of 10).

Sanding/Polishing - Resistance to fuzzing (High of 10).

Finishing - Ability to absorb stain evenly, take oil and water based finishes without bleaching (High of 10).

Specific Gravity - Green volume, oven dry weight.

Weight Per Cubic Foot - Lbs at 12% moisture content.

Weight per MBF - Lbs per 1000 board feet at 12% moisture content, 4/4 rough.&

Hardness - Pressure to bury half of 1.13cm ball perpendicular to the grain (High of 10).

Shrinkage Volume - Percent of across grain shrinkage from green to 6% moisture content.

Static Bending - Resistance to rupture (High of 10).

Impact Bending - Resistance to fiber stress (High of 10).

Compression - Crushing strength, resistance to weight applied parallel to grain (High of 10).

Dimensional Stability - Resistance to expansion and contraction due to climatic variations (High of 10).

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