Barcol Hardness Tester

Originally named the Barber-Colman Impressor, the Barcol Hardness Tester was developed by Walter Colman during World War II as a portable device to evaluate the hardness of materials. The U.S. Air Force required a handheld method to check the hardness of rivets, as there were concerns that standard-quality rivets might be replaced with soft lead or wooden rivets, potentially compromising aircraft safety during flight.

Easy to Use

The device’s lightweight design makes it highly portable, allowing for easy on-site testing without requiring extensive setup. The device operates by pressing its tip against the material under test. The depth of penetration of the indenter determines the material’s hardness. This is translated via a tension spring and lever mechanism to a reading on the dial.

Suitable for a range of materials, including soft metals, plastics, fiberglass sheets, and composites, the Hardness Tester is adaptable to diverse applications, from inspecting fire department ladders to testing rivets on aircraft. The indenter point’s small diameter enables precision, but it’s best suited for homogeneous materials.

Application

For accurate results, the test area should be smooth, free from mechanical damage, and at least 0,08 cm (1/32 inch) thick with a minimum distance 0,32 cm (of 1/8 inch) from edges. Note that the tester may show variations in readings for materials with a coarse or fibrous structure and is unsuitable for curved surfaces. The testing method is similar to the Shore D hardness test, which also uses an indenter, though Shore D uses a rounded tip, while Barcol uses a pointed one. It should be noted that Barcol hardness is not suitable for sloped or curved surfaces.

When pressure is applied to the device, the pointed tip penetrates the material, and the hardness value is displayed on a dial graduated from 0 to 100.