Hardness Test Pencil (method A)

Product Description

The BGD 511 Hardness Test Pencil is designed to simply and quickly test the resistance of a coating to scratches (such as writing marks or metal marking) using a usually hand-held, loaded stylus. This instrument is especially suitable for curved surfaces or small test specimens (minimum dimensions 30 mm × 50 mm). It conforms to ISO 22557 “Paints and Varnishes – Scratch Test Using a Spring-Loaded Pen.”

The test can be performed by Method A, using a pointed stylus (diameter 0.50 mm, 0.75 mm, or 1.00 mm), or by Method B, using a disc stylus (made of stainless steel, copper, thermoset, or PMMA [Polymethyl methacrylate]). The stylus, loaded with a test force between 0.5 N and 20 N, is manually moved over the coating’s surface. The resulting damage is then visually examined and assessed, often with a magnifier.

Standards

• ISO 22557

Technical Specification

Operating the Hardness Test Pencil is extremely straightforward. The desired spring tension is set using the slider. Holding the instrument vertically, place the tip on the test surface and draw a line 5 to 10 mm long at a speed of approximately 10 mm/sec. The stylus should produce a scratch that is just visible to the naked eye. If the spring tension is too high, the scratch will be clearly visible; if it is too low, no scratch will appear. The applied pressure is fixed by locking the slider and is marked in Newtons.

Three scales are engraved on the test pencil for the different pressure ranges:

• No. 1:   0-3 N (blue marking, graduation 0.1 N)
• No. 2:   0-10 N (red marking, graduation 0.5 N)
• No. 3:   0-20 N (yellow marking, graduation 1 N)

Main Technical Parameters