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Old 26th Mar 2019, 12:00 pm   #25
ajgriff's Avatar
Join Date: May 2004
Location: Halifax, West Yorkshire, UK.
Posts: 2,576
Default Re: Polishing old cloudy transparent plastics

The principle abrasive used in proprietary plastic polishes is cerium oxide. This can be acquired economically (minimal packaging and marketing hype) in the form of a white powder. I bought 50g for £5 about five years ago which may sound a lot for a couple of teaspoons full but it really does go a long way. From memory I've used it to remove scratches from and polish turntable covers, meter lenses, CDs, bakelite 'phones, plastic 'phones, aluminium trim, sheet steel, car light lenses, mirrors & a car windscreen. All this and I still have about 10g left. Incidentally, power tools are a practical necessity for glass but plastics and soft metals must be done manually.

Tractionist also mentioned using wet & dry paper for deeper scratches ie, ones you can feel with a thumbnail, which is realy the only way to approach the problem. It does take a leap of faith to see a transparent surface turning opaque as a deep scratch is erased. However, it's very satisfying when bright and shiny transparency is restored with polishing. The abrasive used for wet & dry paper is usualy silicon carbide which is an exremely hard compound just like cerium oxide. The difference between them is that the carbide particles have a sharp jagged surface whereas the oxide particles are smooth and rounded.

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