Loblolly pine microtome sections 100μm thick were tested wet in tension. This thickness was approximately double the outside diameter of tracheids. Results indicate a curvilinear relationship between tensile strength and specific gravity of microspecimens combining both earlywood and latewood zones. Contrary to expectations the rate of change in slope of curve, expressed as tangent angles, decreased as specific gravity increased. Both tensile strength and stiffness values of these microspecimens are low in relation to their specific gravity. This reduction in strength and stiffness is probably related to the low ratio of microspecimen thickness to tracheid diameter, but needs further investigation. If the proper ratio between microspecimen thickness and tracheid diameter is determined, the transitional variation in tensile strength and stiffness within growth ring may be accurately established. The transitional variation in specific gravity can be successfully established from microtome sections, however the method is time consuming and not completely free of errors. This study is a part of a larger study that concerns the determination of several mechanical properties of the earlywood and latewood zones of southern yellow pine in relation to their anatomical characteristics. The part presented in this paper concerns the following objectives: 1. To determine whether microtome sectioned specimens can be successfully used to establish the transitional variation in physical properties within loblolly pine (Pinus taeda L.) growth rings. 2. To investigate the relationships between tensile properties and specific gravity obtained from testing microtome specimens within loblolly pine rings. © 1969 Springer-Verlag.
