Do Board Grade and Flute Size Affect Pin Adhesion

Desi asks,

Do box grade and flute size have an effect on the Pin Adhesion Test? Also, I know that the double backer bond is stronger than the single facer so how do we know which side failed first in the normal pin adhesion test since no side is being held firmly to the base?

There is some thought that at the lower grammages and lower caliper the liner is not “rigid” enough to support itself or lay flat enough for the pins to do an adequate job of breaking the glue line. I have seen pin targets as low as 42 for 23# C flute.

The Pin Adhesion test is selective separation. The weakest point will be the first to give. In this test one side is supported while the other is tested, therefore sides should are tested separately. Using the TAPPI method, it should not be possible to test both sides in the same test.

If you search “pin adhesion” on this site you may find more helpful information.

— Ralph

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