Achieving Polished Edges on Laser Cut Acrylic

Why Laser Cut Acrylic Edges Look Frosted

The laser melts and vaporizes acrylic along the cut path. The resulting edge is smooth but microscopically rough — it scatters light, producing the frosted appearance. This is unacceptable for optical pieces or display items.

Flame Polishing

A hydrogen or propane torch briefly melts the surface layer of the acrylic edge, which flows into a smooth, clear surface. Hold the torch 3–5cm from the edge and move at a steady 25mm per second. Never stop moving while the flame is on. One pass for material under 3mm, two passes for thicker. Let cool completely between passes.

Scraping and Sanding

For flat edges: scrape with a sharp cabinet scraper, then sand progressively — 220, 400, 800, 1500 grit wet — then polish with Novus Plastic Polish #1. Achieves optical clarity but is time-intensive for production.

Laser Parameters for Cleaner Raw Edges

Slow speed, lower power, more passes produces cleaner edges than fast/high power single pass
Focus 0.5–1mm below the material surface for cast acrylic cuts
Remove protective film before cutting — it causes uneven edge heating

Material Quality

Cast acrylic polishes to optical clarity. Extruded acrylic has internal stresses that cause micro-fractures during polishing — it never achieves the same clarity. For optical applications, always specify cast acrylic.

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