4.1 The purpose of this test method is to provide a relative measurement of the combustibility of fire-retardant-treated wood specimens based on their percentage loss in weight under controlled fire exposure conditions (1).3 In addition, other possible data include rate of weight loss, time of flaming and afterglowing, increase in temperature, and maximum vertical flame progress.

4.2 This test method is not sufficiently large scale to evaluate the suitability of a given treated product for building construction, but it is a convenient method to use for purposes of development or as a quality-control test during manufacture.

4.3 This test method gives a procedure for sampling and preparation of test specimens from a lot of treated material in which complete penetration is a requirement. A procedure is also given for the sampling of charges at a treating plant for purposes of quality control of the treatment process.

4.4 This test method has proven useful for evaluating comparative fire performance effectiveness of fire-retardant chemicals and treatment formulations for wood and wood products (2-5).

4.5 In this test method, the specimens are subjected to one or more specific sets of laboratory test conditions. If different test conditions are substituted or the anticipated end-use conditions are changed, it may not be possible by or from this test method to predict changes in the fire-test-response characteristics measured. Therefore, the results are valid only for the fire test exposure conditions described in this procedure.