7. Assessing the Result of a Pull-Off Adhesion Test

New and updated edition.

When testing coating adhesion using a pull-off adhesion tester, typically the dolly, or pull stub, is completely pulled off the surface, and you record the resultant tensile pull off force. You then assess the dolly face and surface, to determine the failure mode; i.e. glue, adhesive, and cohesive failures.

This video will guide you through how to record the result of a pull off adhesion test in accordance with ASTM D4541 and ISO 4624.

When the coating has failed within the layer, leaving the same coating on both the dolly and the test panel, it is known as a cohesive failure.

Adhesive failures occur when either the coating has failed at the interference with another coating, (leaving coating on the dolly and another coating on the substrate), or when the coating has failed at the substrate, (leaving coating on the dolly, and a bare substrate).

It is possible for both adhesive and cohesive failures to occur during one test.

Many National and International Standards require the user to record both the pull-off force and the nature of the failure as an estimated percentage to the nearest 10%.

Once the dolly and substrate have been assessed, the dolly diameter, the pull rate, whether you did or did not cut around the dolly, the pull off force, and the percentage cover of the failure should all be recorded.

For most gauges you will have to record this manually.

The Elcometer 510 Automatic Pull-Off Adhesion gauge is different.

The gauge allows the user to store all of this data against each reading, which you can later transfer via USB or Bluetooth to ElcoMaster, Elcometer’s free software application, which allows you to create professional inspection reports, instantly.

When using ElcoMaster on your Android or Apple mobile device, you can instantly add photos to your test results – a quick and easy way to provide evidence of the result.

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 [email protected] or visit our website: http://elcometer.com/en/coating-inspe...

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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