Prong test and stress development during conditioning in red oak

Lumber must be conditioned to relieve transverse drying stresses. The stand ard prong test has been used for many decades to determine the conditioning time needed for complete stress relief. However, no work has been directed at the proper procedures or interpretation of this test. The purpose of th is study was to obtain initial information on the factors influencing the p rong test and stress development. The major factors studied were prong thic kness and surface moisture content. Data on stress distribution, moisture g radient, and prong response were obtained periodically throughout condition ing of red oak. Slicing, a residual strain release method, was used to obta in the stress distributions. The results demonstrated that the prong respon se is a function of prong thickness and stress distribution. Additionally, an explanation of how the stresses are altered was proposed. Further studie s concerning conditioning schedules need to be performed before standard le st procedures can be suggested.