The ability to quickly and accurately evaluate and predict long-term weathering performance of factory-applied coatings is of paramount importance in making sound business and technical decisions.

It is important to include control specimens of known field performance to determine the efficacy of this practice for specific substrate(s) and coating system(s). These reference specimens may include materials known to possess acceptable and unacceptable field performance for the defect(s) under consideration.

Results derived from this practice are best used to compare the relative performance of materials tested at the same time in the same device.

The inclusion of control specimens and their resulting data will assist in dealing with test variability caused by seasonal or annual variations in important climatic factors. However, quantitative service life approximations “acceleration factors” based on the above data are not recommended unless a sufficient number of field/accelerated test comparisons have been analyzed to compute the statistical significance of the “time to failure” estimate for each exposure.

A minimum of two replicates for both control specimens and test specimens is recommended to allow statistical evaluation of results.

1.1 This practice covers techniques to accelerate weathering effects of factory-coated embossed hardboard using apparatus described in Practice G 90.

1.2 This practice is based upon Cycle 1 of Practice G 90 (concentrated natural sunlight with periodic surface water spray) plus a soak-freeze-thaw cycle (see 5 of this practice).

1.3 Testing by use of the methods described in this practice may be employed in the qualitative assessment of weathering effects. The relative durability of coated hardboards may be best determined by comparison of their test results with those of pass-fail control specimens derived from real time exposure test experience (see 8.2 for specific guidelines).

1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.