Standardized Laboratory Methods for Evaluating Matte Print Coating Burnishing
Standard laboratory burnish evaluation uses controlled sled friction and 60-degree delta gloss measurements to quantify matte coating asperity degradation.
Gakushin Tester
Mechanical Friction
Testing apparatus of this design assesses the resistance of printed and coated substrates to surface wear from repetitive reciprocal sliding. The Gakushin tester is widely used to evaluate friction damage on paperboard packaging and heavy printed sheets. It simulates the abrasive forces that packages experience during transport.
Slide Motion
Operations involve placing a test specimen on a curved specimen holder while a weighted arm with a curved contact head rubs against it. The tester utilizes a reciprocating mechanism that moves the head across the specimen in an arc. A force of two newtons is typically applied to the arm, and the machine completes a predetermined number of cycles at a fixed speed.
This action exposes the ink or coating to intense friction, and the amount of rub off is evaluated visually or with a densitometer.
Board Sensitivity
Proper specimen preparation requires secure mounting to prevent the board from shifting during the test run. Friction evaluation must be performed in a temperature controlled room to keep moisture levels stable. This method does not apply to very thin or flexible plastics that can bunch up under the rubbing head.
Heavily textured papers may give inconsistent results due to the uneven distribution of the abrasive forces.