The Barcol #934-1 impresser is the industry standard hardness tester for checking the hardness of softer metals and hard plastics in the field. Typical applications include brasses, light alloys, GRP and epoxy composites. As a guide, optimally cured polyester layup or gelcoat resins should give Barcol Hardness readings of approximately 40 ~ 42 at 20 °C (68 °F). (See manufacturer's data sheets for specific information.) Under-cured resins provide lower mechanical strength than optimally cured examples and are more likely to distort at elevated temperatures. Moisture absorption will also be greater, increasing the risk of blistering (Osmosis). Where Barcol Hardness figures are quoted in reports without a model number it is usually safe to assume that a #934-1 Impresser was used. Kit includes the Barcol Impresser, two spare indenter points, test disks, wrench and detachable foot all housed in a foam lined carry case.
See details of the Barcol #935 and #936 impressers for use on softer materials.
Please note that hardness readings from plastics will vary with temperature, dropping significantly as the Glass Transition Temperature (Tg) is approached. Hardness should be measured with the gauge and specimen at 20 °C (68 °F) unless otherwise specified. Surface temperature may be measured with an infra-red thermometer.
