3. Selecting the Most Appropriate Position for a Pull-Off Adhesion Test

New and updated edition.

When preparing a pull-off adhesion test, it’s important to select an appropriate position on the substrate to adhere the dolly to, as poor positioning can result in low pull-off values or invalid tests.

This is true regardless of the pull off adhesion tester you are using.

The flatness of the surface is critical. Test standards require that the dolly is pulled off perpendicularly to the test surface – a uniform, tensile pull.

If the dolly is adhered on a ridge or bump, as opposed to a clean flat surface, when the gauge tries to pull the dolly off the surface, the moment of fracture pivots around the ridge or bump, tearing the dolly off, and not pulling perpendicularly to the surface - leading to an inaccurate test.

It is essential to position the dolly on a flat surface, located away from any bumps, seams or edges, and have sufficient space around it for the gauge or actuator to be attached for a uniform, perpendicular pull.

All pull-off adhesion testers follow the same principle. A properly prepared dolly, or pull stub, is glued to the prepared coating, and, once the glue has fully cured, the dolly is pulled off -perpendicularly (or 90 degrees) from the surface. The resultant tensile pull-off force, together with the dolly diameter, and the conditions of the dolly, are all recorded.

For more information on measuring pull-off adhesion on coated substrates using Elcometer's range of pull-off adhesion gauges, please contact Elcometer at sales@elcometer.com or visit our website:

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STANDARDS:

Elcometer 106

AS 1580.408.5, ASTM D 4541, AS/NZS 1580.408.5, EN 13144, EN 24624, ISO 4624, ISO 16276-1, JIS K 5600-5-7, NF T30-062, NF T30-606

Elcometer 106/6

ASTM D 7234, BS 1881-207, DIN 1048-2, EN 1542, EN 12636

Elcometer 506

ASTM D4541, ASTM D7234, AS/NZS 1580.408.5, BS 1881-207, DIN 1048-2, EN 12636, EN 13144, EN 1542, EN 24624, ISO 16276-1, ISO 4624, NF T30-606, NF T30-062

Elcometer 510

ASTM C1583, ASTM D4541, ASTM D7234-12, AS/NZS 1580.408.5, BS 1881-207, DIN 1048-2, EN 1015-12, EN 12636, EN 13144, EN 1542, EN 24624, ISO 16276-1, ISO 4624, NF T30-606, NF T30-062

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