Source link: https://www.smooth-on.com/page/preparation-surfaces-epoxy-adhesive-bonding/
Porous materials are simple provided they are dry.
Surface should be sanded till clean and free from dust
Non-porous surfaces, e.g. metal and plastic materials
Surfaces should be degreased, dried, and roughened by sanding, sandblasting or chemical etching.
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It is more than sufficient to follow the provided instructions for an adhesive, i.e. read its technical data sheet. The source link provides very specific procedures for different materials. The procedures seem to be very specific and require technical expertise to perform. We would not resort to procedures researched online unless the technical data sheet of adhesives do not explicitly provide surface preparation instructions.
Source links:
https://www.smooth-on.com/page/preparation-surfaces-epoxy-adhesive-bonding/
https://www.smooth-on.com/page/preparation-surfaces-epoxy-adhesive-bonding/