This method is for making test boards for the evaluation of stock used for structural-type insulating boards. It applies only to pulps suitable for making boards which are normally 9.5 to 25 mm (3/8 to 1 in.) in thickness and may include modifications to the pulp such as the addition of resins or bituminous binders. The physical properties of the test boards are determined by test methods as specified in TAPPI T 1003 "Flexural Resistance and Deflection of Insulating Board," Commercial Standard CS 42-49, and Federal Specification LLL-F-321b. The stock used for the preparation of the test board by this procedure may or may not be sized. The subject of sizing has not been included in the method because of the diversity of sizing materials and processes in common use for the manufacture of structural-type board. The procedure described requires test boards to be prepared at four different densities. These are tested, and the results are plotted against board density. A "usual dry density" is selected by experience, and the transverse strengths and other physical properties at that density are recorded. The term "usual dry density" is used in this procedure to designate the normal moisture-free density of the boards into which the pulp under test is to be made. It corresponds to the customary density expected at the mill and may vary from approximately 240 to 352 kg/m(cubed) (15 to 22 lb/ft ) . If not otherwise required, use a board density of 288 kg/m(cubed) (18 lb/ft ) for evaluating the pulps.