Defocusing and Other Hints For Engraving Acrylic

Engraving acrylic can produce beautifully smooth and polished results—especially when using the defocusing technique. This tutorial walks you through how to effectively defocus your laser, engrave different types of acrylic, and improve your overall finish using simple, tested tricks.

Why Defocus the Laser for Acrylic Engraving?

When engraving acrylic, defocusing the laser slightly from its optimal point can create a more even, smoother finish. This technique diffuses the beam slightly, softening the engraved surface and reducing harsh edges.

How to Set the Defocus Manually

For ⅛" (3mm) acrylic, manually set your laser’s focus height to about 0.3 inches above the surface before engraving. This minor adjustment helps achieve a clean, uniform look.

💡 Tip: Test different focus settings using small shapes (like circles or squares) to find the best result for your specific material and machine.

Engraving Mirror and Clear Acrylic

When working with mirror or clear acrylic, always flip the piece over and reverse your design before engraving. This way, you're engraving from the back, which allows the finished image to be seen clearly through the front and gives a more polished, professional appearance.

Order of Operations for Mirror Acrylic

1. Engrave first, then cut.

2. Never cut first and then engrave—cut edges can re-melt during engraving.

Cutting Mirror Acrylic: Avoid Re-Melting

All mirror acrylic is extruded, which means it’s prone to melting back together if not handled correctly. If you cut it and leave it in the laser while engraving, the heat can fuse the edges again.

To prevent this:

• Cut at the highest speed your machine allows—usually around 170–180 speed.

• Remove the cut pieces immediately after cutting to prevent re-bonding.

⚠️ Avoid slower cutting speeds like 150, as they increase the chances of the edges melting back together.

Masking and Soap for Cleaner Engraving

Before engraving, remove the masking from the side you plan to engrave. Then, apply a thin layer of liquid dish soap directly to the acrylic surface. This helps reduce burn marks and improves the overall clarity of the engrave.

You can also:

• Remove the masking from both sides of the acrylic.

• Apply dish soap to both sides if extra protection is desired.

Here is a YouTube video that shows how to do this: