SYMPOSIA PAPER Published: 01 January 1994

Methods of Predicting the Adhesion of Silicone Sealants to Anodized Aluminum


The quality of silicone sealant adhesion to anodized aluminum varies widely. Key parameters that affect adhesion are the degree of surface sealing, the nature of the cleaner, and the time period allowed between cleaning the substrate and sealant application. While the cleaners display different effectiveness in removing organic contamination from the anodized aluminum surface, this effectiveness does not correlate with adhesion quality. It is hypothesized that by adsorbing on the anodized aluminum substrate the cleaning solvents ‘condition’ the surface for improved silicone sealant adhesion. This conditioning effect diminishes, as the cleaning solvents desorb over time. For a given cleaning solvent, optimum adhesion is observed for a certain degree of surface sealing. Adhesion to unpigmented anodized aluminum substrates can be predicted by measuring the degree of surface sealing according to the ISO 2143 acid etch method. For pigmented anodized aluminum substrates, electrical phase shift measurements can be used to predict adhesion quality.

Author Information

Descamps, P
Parc Industriel, Seneffe, Belgium
Iker, J
Parc Industriel, Seneffe, Belgium
Wolf, AT
Dow Corning Corporation, Midland, Michigan
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Developed by Committee: C24
Pages: 95–106
DOI: 10.1520/STP14003S
ISBN-EB: 978-0-8031-5289-2
ISBN-13: 978-0-8031-1993-2