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. |
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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) |
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