Pretreatment of Specific Substrates

For metallic adherends most of these prelreatments either involve acid etching or an acid etch followed by an acidic anodising process. However, individual alloys and the particular surface structures caused by different heat treatments may respond differently to a given pretreatment for example, aluminium clad aluminium alloys (Alclad ) as opposed to the bare , unclad alloys. 

The eifectiveness of one pretreatment over another can he shown only by comparative trials using both the type of metal and the adhesive specified for the work. 

In virtually all cases where chemical pretreatment has been used, the water-break test can be used to confirm the effectiveness of the process. 

Surface modification of plastic materials is, nowadays, frequently carried out by exposing the surface to be bonded to a controlled flame, plasma or corona discharge. 

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