Acrylic looks the same on the shelf but behaves very differently under the laser. Getting this right is the difference between a frosty clean result and a melted mess.
Cast vs Extruded — The Key Difference
| Property | Cast Acrylic | Extruded Acrylic |
|---|
| How made | Poured into molds | Pushed through rollers |
| Laser engrave | Bright white frosted mark ✓ | Faint grey, almost invisible ✗ |
| Laser cut | Slightly more melt | Cleaner cut edge |
| Price | More expensive | Cheaper |
| Flexibility | More brittle | Slightly more flexible |
| ID | Paper masking on both sides (often) | Usually one-side masking |
Rule: Use cast acrylic for engraving. Extruded for cutting.
Identifying Cast vs Extruded
- Cast: paper/film masking on both sides, slight cloudy tint when held up to light
- Extruded: one side masking, very clear and flat
- Ask your supplier — or test a small corner first
Engraving Settings (Cast Acrylic)
| Color | Speed | Power | Result |
|---|
| Clear cast | 3000 mm/min | 30% | Light frost |
| Clear cast | 2000 mm/min | 45% | Standard frost |
| Clear cast | 1200 mm/min | 60% | Deep frost |
| Black cast | 2500 mm/min | 35% | Reveals clear underneath |
| Colored cast | 2000 mm/min | 40% | Good contrast |
Cutting Settings
| Thickness | Speed | Power | Passes |
|---|
| 2mm | 400 mm/min | 90% | 3 |
| 3mm | 300 mm/min | 100% | 4 |
| 4mm | 200 mm/min | 100% | 6 |
Tips
- Leave masking on while cutting — protects surface from smoke residue
- Remove masking before engraving — masking reduces mark contrast
- Air assist for cutting — prevents melting and flaming
- Defocus slightly for engraving — move bed down 2–3mm for softer, wider marks
- Flood with water for cold cutting on thin pieces (eliminates melt marks)
Common Issues
| Problem | Cause | Fix |
|---|
| Faint/no mark | Extruded acrylic | Switch to cast |
| Melting on cut edge | Too slow or too many passes | Faster speed, fewer passes with air assist |
| Smoke residue on surface | Masking removed | Leave masking on for cuts |
| Crazing (micro-cracks) | Too much heat | More passes at lower power |