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Removing Scratches from Thin Clear Coat Plastic Parts

February 5, 2008

I'm working on a project to refinish small plastic lenses for cellular phones. The parts are polycarbonate substrate with a thin polyurethane clear coat. The issue we are having is how to handle the scratches in the thin layer of clear coat. The clear coat is thin enough that an abrasive buffing-type operation is not effective. The abrasive attacks the edge of the scratch and it propagates. I have tried several types of abrasive media, from buffing wheels with 2-5 micron polishing compound, to automotive paint polishing compounds from pepboys.

My question is this: Does anyone have any suggestions on how to fill in scratches using an additive process? These parts are clear and need to retain their optical clarity. The majority of the scratches are in the polyurethane clear coat.

This application can be applied to hundreds of different electronic consumer products, from cell phones, to PDAs and ipods.

Rob Dixon
Process Engineer - Rochester, New York

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A recent response (Jan. 26) to letter 30046 may contain the info you are looking for, Rob. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
February , 2008