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
Les Janka Les Janka Leslie A. Janka is President-Saudi Arabia for Quincy International LLC, resident in Riyadh Saudi Arabia.. He has more than 25 years experience as an international affairs specialist in the U.S. Government, business consulting and academic institutions. Prior to joining Quincy International, Janka was President of Raytheon Arabian Systems Company in Riyadh, Saudi Arabia. Prior to managing his independent consulting firm, Les Janka International from 1995 to 2007, he directed the international practice of the energy utility and telecommunications specialty consulting unit of Arthur Andersen, LLP. Janka is a frequent writer and lecturer on the Washington political scene, specializing