Edge Polishing

Sanding, polishing. buffing and edge finishing give acrylic sheet an attractive, smooth transparent edge.

The edge of a saw cut must be finished. Scraping is the easiest edge finishing technique. A knife or almost any piece of metal with a sharp, flat edge can serve as a scraper. Special acrylic scraping tools are available.

Polishing, done on a stationary polishing head, creates the best finished edge. An 8-inch to 14-inch diameter bleached muslin buffing wheel with bias strips that give the wheel a pleated appearance is recommended. This design runs cooler than a stitched wheel and does a faster job. A medium polishing compound gives a good finish. For a high-luster finish, remove sanding marks with a fast cutting compound, then final buff with a high-luster compound.

When buffing edges, avoid excessive heat build-up. Too much heat can induce stress into the sheet and lead to crazing. Edge finishing machines are also commercially available.

Flame polishing with a hydrogen-oxygen torch, adjusted for a narrow, 3-inch-long flame, will produce a highly-polished, clean edge. Hold the torch at the angle and draw the flame along the edge of the sheet. If the first pass does not produce a completely polished edge, let the piece cool, then try a second pass. Annealing the part after flame polishing decreases the stress imparted and reduces the chance of crazing.

If scratches or machining marks are not too deep, the surface can be buffed without wet sanding. If the imperfections are too deep to be removed by polishing, wet sanding and then polishing will work.