Some limitations are imposed by incompatibilities of barrier material with chemical agents. Chemical resistant gloves, suits, etc. are rated on the ability to prevent contact with special types of chemicals. This performance is usually rated in terms of "breakthrough times", that is how long it takes for a particular chemical to pass through a particular barrier material under test conditions. This kind of information should be obtained from manufacturers (or from other reputable sources of technical information such as NIOSH, OSHA, etc.)and used to determine (a) What types of barrier materials are best suited for working with.