TAPPI T821 – Pin Adhesion of Corrugated Board by Selective Separation

TAPPI T821 is used to measure the force required to separate corrugated board between the flute tips of corrugated medium and its linerboard facings.

TAPPI T821 standard, developed by the Pulp, Paper and Conversion Industry Technical Association (TAPPI), defines a test method to measure the force required

to separate the corrugated cardboard between the corrugated ends of the corrugated cardboard and its primer coating surfaces.

This is a compression method.

The two parts are pushed apart by two rows of pins (support and pressure pins) spaced according to the groove dimensions.

Good adhesion of the corrugated media to their coating is essential in obtaining high quality corrugated boards and boxes.

The adhesion strength (PAT) test provides a means to determine the nature and strength of the bond formed during the joining process and is used to detect certain

manufacturing defects such as poor adhesive penetration, spotty adhesion, and cardboard with low internal bond strength.

The test method described in this standard measures the Z-direction force required to selectively separate the inner or outer surface of the corrugated board.

But when a liner is too flexible, it tends to bend around the pressure pins and a shear error will occur rather than a straight Z-direction error resulting in lower readings.

*** Before conducting TAPPI T821 , it is important to read the entire specification. Standards can be obtained from appropriate standard authorities.