This test is used to determine the adhesion-strength of coatings on a surface, such as paint or primer on wood.

DeFelsko PosiTest AT-A

Data collection screen of the PosiTest AT-A.

This instrument is an automatic pull-test system that uses an actuator to exert pressure on the sample while pulling the applied dolly off.  The dolly is applied to the surface coating being tested in advance using at two-part epoxy.  Once the epoxy has set, the test can be conducted.  The instrument measures the amount of pressure applied in psi and shows a curve of psi applied over seconds elapsed until the dolly and coating separate from the substrate; if the instrument is connected to a computer, it can log the data using PosiSoft software.

This instrument has been used in the study of paint and primer systems on weathered historic wood samples.

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PosiTest AT-A instrument with the actuator clamped around a dolly on one of the painted wood samples.

 

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National Center for Preservation Technology and Training
645 University Parkway
Natchitoches, LA 71457

Email: ncptt[at]nps.gov
Phone: (318) 356-7444
Fax: (318) 356-9119