Shore D scale is for testing the following materials:
Rubber: Hard
Plastics: Harder grades such as rigid thermoplastics, plexiglass, thermoploystrene, vinyl, sheet, cellulode acetate, thermosetting
Laminates (ie fornica)
Other: Paper filled calendar rolls, calendar bowls, etc. (materials that would not normally indent under fingernail pressure, such as a pocket comb or bowling ball).