DeFelsko PosiTest AT Guide D'utilisation page 6

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.
Cohesive fracture:
fracture occurs within a coating
layer (same coating on dolly
face and coated surface).
Adhesive fracture:
fracture occurs at the interface
between layers (coating on
dolly face differs from surface).
Glue failure: visible separation of the glue from itself,
the coating or dolly (no coating visible on the dolly face).
Cohesive fracture
(within a layer)
Glue failures typically occur when the glue is improperly mixed or
the coated surface has not been adequately prepared (see pg.2).
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.
Analysis of Test Results
Dolly
SUBSTRATE
Adhesive fracture
(between layers)
Dolly Face
Glue
4
Coated Surface
Glue failure
(coating/glue)