In certain environments, workers can be exposed to or come in contact with liquid chemicals capable of causing them harm. The primary requirement of the protective clothing worn by these personnel is reduction in direct skin contact with the chemical. To understand liquid penetration resistance of the material used in construction of the protective clothing, testing is performed using procedures stated in American Society Testing and Materials (ASTM) F 903, Standard Test Method for Resistance of Protective Clothing Materials to Penetration by Liquids.

The outside surface of the material specimen is continuously subjected to a liquid chemical challenge for a specified time and pressure sequence. Observations of visible penetration of the liquid are noted. The sample is mounted in the test cell to form a closed chamber for the external or test side of the material. As such, the specimen is acting as a partition separating hazardous liquid chemical from the viewing side of the test cell. In use, the viewing side of the test cell is presumed to be human skin. A challenge liquid is introduced into the chamber contacting the material surface. After a designated observation period, the air pressure is raised from 0 psig to a predetermined pressure and time duration. During the test, the surface of viewing or skin side of the specimen is monitored for the appearance of the liquid. If the liquid passes through the specimen, the material fails the test for resistance to penetration of that liquid. If liquid appears on the surface or if discoloration is noted, the test is terminated. Results are reported as either pass or fail.