Recently, a customer was comparing coating film hardness of comparable water-base coatings for their application, and ratings of 2B and 2H hardness were being discussed.
We thought we would review pencil hardness which is an accepted method to measure coating hardness using various grades of lead pencils. The hardness of the coating is determined when the grade of pencil hardness does not mark the coating. The pencils of various hardness are prepared with a blunt end, using a file or sanding paper, then pushed across the coating at 45 degrees.
Pencil hardness classifications start at 9B (softest) through HB (medium) to 9H (hardest). Some U.S. made pencils will use a number system. Automotive, industrial, and wood coatings typically fall between F and 4H in pencil hardness.
9B 8B 7B 6B 5B 4B 3B 2B B(1) HB(2) F(2.5) H(3) 2H(4) 3H 4H 5H 6H 7H 8H 9HHandle: news/what-does-2h-coating-hardness-mean