This test method is useful for establishing the integrity of composite rod. The presence of voids, cracks, and hollow fibers are considered detrimental to the structural integrity of the composite and may cause reduced electrical resistance and increased current leakage.

A perfect composite would be flaw-free, and there would be no possibility of wicking. Composites of this type are virtually nonexistent, as there will typically be entrapped air in the resin developed during manufacture, occasional hollow fibers, and occasional cracks due to thermal stresses.

This test method is intended to provide a tool for measuring the extent of flaws in a composite over very short lengths of material. The presence of wicking over 1 in. [2.54 cm] lengths may not necessarily imply that the composite will perform unsatisfactorily for its intended end-use. Therefore, interpretation of test results should be made with care.

This test method was developed as a technique for estimating quality and consistency of pultruded rod stock, which is a composite of resin and reinforcement. The process may also affect the quality of the product. It should be useful for a manufacturer in determining whether any gross changes in quality have taken place due to process or raw material changes.

Since the results of this test are so sensitive to sample size, penetrant type, penetrant used, viscosity, duration of test, and other factors, no attempt to arrive at or recommend development of a specification for these materials has been made. It is suggested that such a specification should be negotiated between supplier and end user.