ISO 16604:2004 describes a laboratory test method for measuring the resistance of materials used in protecting clothing to penetration by blood-borne pathogens. This test method uses a surrogate microbe under circumstances of constant liquid contact. Protective clothing "pass/fail" determinations are based on the detection of viral penetration at an exact hydrostatic pressure using the ISO 13994 test apparatus.

This test method is not always powerful in testing protective clothing materials having thick, inner liners which readily absorbs the challenge fluid.

This test method includes a sensitive assay procedure. Because of the length of time essential to complete this test method, it might not be suitable for use as a material or protective clothing quality control or assurance procedure.