The Barber-Colman Impressor is a portable test instrument for checking the hardness of various soft metals, plastics and other low density materials. The Impressor and it's original wooden case are shown here.
This fiberglass reinforced boat is being checked for hardness under temperature ranges from -37F to 128F at the American Petrochemical Corporation research center in Minneapolis. (Photo date: May,1960)
To order the Barcol tester, click here.