Plastic Repair: Adhesion Promoter

Adhesion promoters, or surface modifiers, are extremely important when making some types of adhesive plastic repairs. If the adhesion promoter is not applied when required, or applied incorrectly, the repair will fail. (although there are some exceptions because some plastics do not require adhesion promoters). Let’s take a look at some ways to avoid this type of repair failure.

Most of the bumpers today are made of an olefin plastic. This type of plastic seems “greasy” and will require adhesion promoters. The first step in any product application is to follow the instructions. Not following the instructions almost guarantees a repair failure. After the repair area surface has been prepared correctly, following the product maker’s instructions, the adhesion promoter is applied. Most adhesion promoters are applied using a mist coat (light dusting). The adhesion promoter should make the plastic look dull, not glossy. If the area has a shine, too much adhesion promoter has been applied and it will likely cause a repair failure. If the surface is glossy, allow it to dry, re-sand the affected area, and reapply the adhesion promoter.

The next thing is to pay attention to flash times. If the adhesion promoter has product applied over it too soon, there will be adhesion problems and the repair will fail. Also pay attention to the sanding time of the product, as sanding too early in the curing of the adhesive will not allow the adhesive time to adhere to the surface.

Finally, make sure the adhesion promoter is for the plastic repair adhesive that is being used. Do not use a paint manufacturer’s plastic adhesion promoter. While both are designed to aid in adhesion, they are designed for totally different materials and will likely lead to a failed repair.

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