Introduction
Introduction
The portable, hand-operated
PosiTest Pull-Off Adhesion Tester
measures the force
required to pull a specified test diameter of coating away from its substrate using
hydraulic pressure. The pressure is displayed on a digital LCD and represents the
coating's strength of adhesion to the substrate.
In accordance with ASTM D4541, D7234, ISO 4624 and others, the
PosiTest
evaluates the adhesion (pull-off strength) of a coating by determining the greatest
tensile pull-off force that it can bear before detaching. Breaking points,
demonstrated by fractured surfaces, occur along the weakest plane within the
system consisting of the dolly, adhesive, coating layers and substrate
.
Basic steps for testing coating adhesion with a PosiTest Adhesion Tester:
1. Dolly & Coating Preparation
The dolly and the coating are cleaned and abraded. (see pg. 4)
2. Adhesive & Dolly Application
The adhesive is prepared and applied to the dolly. The dolly is then adhered to
the coated surface and the adhesive is allowed to cure. (see pg.4)
3. Test Area Separation - Optional step
The test area of the coating is separated from the area surrounding the dolly by
cutting or drilling. (see pg. 5)
4. Pull-off Test
a) PosiTest AT (manual)
(see pg. 6)
b) PosiTest AT-A (automatic) (see pg. 8)
5. Analysis of Test Results
The dolly and the coating are examined and evaluated to determine the nature
of the coating failure. (see pg. 10)
6. Store Pull-Off Test Results - Optional step
The PosiTest’s internal memory stores maximum pull pressure, pull rate, test
duration and dolly size for up to 200 pulls. (see pg. 10)
Page 3
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