Hoff­man Scratch
Hard­ness Tester

Scrape
Adh­e­sion Test

The Hoff­man Scratch Hard­ness Tester was devel­oped for the com­par­a­tive eval­u­a­tion of scratch resis­tance and adh­e­sion of many types of coat­ings.

• Sim­ple pocket size tester
• Ideal for field use and demon­s­tra­tions

This instru­ment con­sists of a four-wheeled car­ri­age, a scale arm gra­d­u­ated from 0-20 that is attached per­ma­nently to the car­ri­age in a coun­ter­poised con­di­tion about the pivot axis, and a scratch tool with a sharp cir­cu­lar rim mounted at 45° to the flat test sur­face.

Pro­ce­dure

To oper­ate, attach rid­ers to the scale arm at the num­bered posi­tions. The car­ri­age is held down firmly by hand and moved in the oppo­site direc­tion, to cause a trail­ing scratch. The large stan­dard rider loads 100 g per divi­sion, while the small rider loads 25 g per divi­sion. This small rider may be used for mak­ing low-range mea­sure­ments involv­ing small incre­ments of pres­sure, or it may serve as a vernier with the large rider in mak­ing more pre­cise medium-range mea­sure­ments.

Scratch Hard­ness
The force neces­sary to cut through the film to the sub­s­trate.

Adh­e­sion
The force required to scrape a path through the film, when the sty­lus begins its motion on an uncoated por­tion of the panel.

Comes com­plete with:
One large stan­dard rider
One small rider and one extra scratch­ing tool
Car­ry­ing case
Oper­at­ing instruc­tions