1
Introduction
The
PosiTest
AT-A 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 dis-
played 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
AT-A
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
(loading fixture,
stub)
, glue, coating layers, and substrate.
Basic Steps to Perform a Pull-Off Test
1. Dolly & Coating Preparation
Clean and abrade the dolly and coating (pg. 3)
2. Glue & Dolly Application
Prepare the glue, apply it to the dolly, and place the dolly on the
coated surface, allowing the glue to cure (pg. 4).
3. Test Area Isolation -
optional
Isolate the test area of the coating from the area surrounding
the dolly by cutting or drilling (pg. 5).
4. Pull-Off Test
(pg. 5).
5. Analysis of Test Results
Examine and evaluate the dolly and coating to determine the
nature of the coating failure (pg. 8).
