SANDING EDGES OF ACRYLIC SHEET

Vical acrylic sheet should not be sanded unless the surface imperfections are too deep to be removed by light buffing and the resulting optical distortion can be tolerated. Use the finest sandpaper that will remove the imperfections. Coarse paper will cause scratches deeper than the original imperfection and additional finishing operations will be needed. If sanding is required, it is recommended that wet sanding be used. The application of water makes it possible to produce a smoother finish, because a fine­grit sandpaper can be used. Without water, this same fine­grit paper would fill up and over­heat the acrylic.

Using wet 600 grit sandpaper wrapped around a rubber­padded sanding block, sand over the scratch using increasingly larger areas of sanding. The sanding should be done in directions mutually 30 degrees apart to produce a diamond pattern. After sanding, polish the Vical acrylic as described below. For very deep scratches, a 240­grit or 320­grit paper will be coarse enough to start the sanding process. This first step should followed, after rinsing, by a 400­grit, and then by a 600­grit paper. Be sure to use plenty of water and rinse the sandpaper frequently to keep it from clogging. With power sanders, only light pressure should be applied to reduce friction. Follow "Polishing Surfaces" procedure for a higher finish.

The same general procedure applies to disc and belt sanders and grinding wheels generally used on the edges rather than the surface of the Vical acrylic. The greater danger of heat generation with mechanical sanders makes the use of water or oil coolants doubly desirable. Wet sanders are preferred, but dry sanders can be used with care. Open coat sandpaper should be used since it does not become clogged as fast as closed coat sandpaper.

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