Pencil Hardness Test
The pencil hardness test is a simple and quick method for testing the surface hardness of coatings and materials with regard to the stresses inflicted by scratching with sharp edges or other rough surfaces.
Pencils of various grades of hardness are moved over the painted surface at an angle of 45o to the horizontal with a force of 7.5 ± 0.1 N. The pencil hardness is defined by those two grades of hardness the softer one of which just produces a writing trace while the next harder one leaves a perceptible scratch on the coating.
The pencil points are sharpened so that the graphite point protrudes about 5mm. The graphite point is face-ground sharp-edged on emery paper with a grain size of 400 for which the pencil is held vertically. The pencil is clamped into the holder block so that the pencil protrudes about 5mm. The instrument is moved over the specimen in the direction the pencil point shows at a speed of about 10cm/s. A pencil hardness of 2H...3H, for example, means that pencil type 2H still writes on the surface while pencil type 3H slightly scratches the surface.
Steel Wool Test
A steel wool test comprises using a super fine #0000 grade steel wool pad (≃8cm2) and rotating the pad with a pressure of 24psi for 100 rotations (≃1rps).
If testing haze then values are generally measured and recorded after 5, 10, 25, 50, 75 and 100 rotations.
Haze and Transmittance Test
ASTM D1003 Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics
This test method covers the evaluation of specific light-transmitting and wide-angle-light-scattering properties of planar sections of materials such as essentially transparent plastic. Two procedures are provided for the measurement of luminous transmittance and haze. Procedure A uses a hazemeter and Procedure B uses a spectrophotometer.
Test Information: http://www.astm.org/Standards/D1003.htm
ASTM D1000 Test
Standard test methods for pressure-sensitive adhesive-coated tapes used for electrical and electronic applications
Test Information: http://www.astm.org/Standards/D1000.htm