Scratch Hardness Tester 293 TRIFORCE
Pencils of various grades of hardness are moved over the painted surface at an angle of 45° to the horizontal with a force of 5 N, 7.5 N or 10 N (± 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.