Barcol hardness test the Barcol impressor was developed by Walter Colman as a hand-held, portable means of assessing the hardness of a material during World War II. The United States Army Air Corps required a hand-held method of checking the hardness of rivets due to concerns that aircraft could be sabotaged by replacing normal rivets with soft lead or wooden ones which would fail during flight. The impressor operates when the tip is pressed against the material in question. The hardness of the material determines how far the tip indents and this is transferred by a tension spring and lever to be read
Draize test are removed with sticky tape), then covered with plastic sheeting. According to the British Research Defence Society, the Draize eye test is now a "very mild test," in which small amounts of substances are used and are washed out of the eye at the first sign of irritation. In a letter to "Nature", written to refute an article saying that the Draize test had not changed much since the 1940s, Andrew Huxley wrote: "A substance expected from its chemical nature to be seriously painful must not be tested in this way; the test is permissible only if the substance has