It is the purpose of this work to secure data on the shrinkage and specific gravity of woods tested under Project 124.  The figures to be obtained are for use as average working values rather than as the basis for a detailed study of the principles involved.

MATERIAL

The material will be taken from that provided for mechanical tests.

RADIAL AND TANGENTIAL SHRINKAGE

Specimens

Preparation:  Two specimens 1 inch thick, 4 inches wide, and 1 inch long will be obtained from near the periphery of each “d” bolt.  These will be cut from the sector-shaped sections left after securing the material for the mechanical tests or from disks cut from near the end of the bolt.  They will be taken from adjoining pieces chosen so that the results will be comparable for use in determining radial and tangential shrinkage. (When a disk is used, care must be taken that it is green and has not been affected by the shrinkage and checking near the end of the bolt.)

One of these specimens will be cut with its width in the radial direction and will be used for the determination of radial shrinkage.  The other will have its width in the tangential direction and will be used for tangential shrinkage.  These specimens will not be surfaced.

Marking:  The shrinkage specimens will retain the shipment and piece numbers and marks of the bolts from which they are taken, and will have the additional mark 7R or 7T according as their widths are in the radial or tangential direction.

Shrinkage measurements:  The shrinkage specimens will be carefully weighed and measured soon after cutting.  Rings per inch, per cent sap, and per cent summer wood will be measured.  They will then be air-dried in the laboratory to constant weight, and afterward oven-dried at 100 deg.C. (212 deg.F.), when they will again be weighed and measured.

VOLUMETRIC SHRINKAGE AND SPECIFIC GRAVITY

Specimens

Selection and preparation:  Four 2” X 2” X 6” specimens will be cut from the mechanical test sticks of each “d” bolt; also from each of the composite bolts used in getting a comparison of green and air-dry.  One of these specimens will be taken from near the pith and one from near the periphery; the other two will be representative of the average growth of the bolt.  The sides of these specimens will be surfaced and the ends smooth sawn.

Marking:  Each specimen will retain the shipment, piece, and stick numbers and mark of the stick from which it is cut, and will have the additional mark “S.”