4
Analysis of Test Results
Glue failures typically occur when the glue is improperly mixed or
the coated surface has not been adequately prepared (see pg.2).
Upon completion of the pull-off test, the dolly and coated surface
should be examined. In addition to pull-off force, many National
and International standards such as ASTM D4541 and ISO 4624
require the nature of the fracture to be recorded.
The PosiTest AT-A model provides an interface to document the
nature of the fracture for each pull-off test (see pg. 10). Fracture
results are included in test reports.
Glue failure: visible separation of the glue from itself,
the coating or dolly (no coating visible on the dolly face).
Dolly Face
Coated Surface
Dolly
Glue
Cohesive fracture
(intercoat)
Adhesive fracture
(between layers)
Glue failure
(coating/glue)
Substrate
Adhesive fracture:
fracture occurs at the interface
between layers (coating on
dolly face differs from surface).
Cohesive fracture:
fracture occurs within a coating
layer (same coating on dolly
face and coated surface).
To Next Page
Loading...
