Why does your laser-marked QR code look gray instead of black?

LaserMarking PC

Why does your laser-marked QR code look gray instead of black? 🔍

We recently worked with a client engraving QR codes and serial numbers onto white PC parts — and the result wasn't the crisp, scannable black they needed. It looked hazy, low-contrast, almost like fog over the text.

The culprit? High TiO₂ content (>8%) in the base material.

Here's what's happening at the microscopic level:

→ TiO₂ is a high-reflectivity white pigment. At 1064nm fiber laser wavelengths, it reflects a large portion of the laser energy away before it can carbonize the resin.
→ The TiO₂ particles that do get trapped in the carbonized layer act like white specks in black ink — diluting the color and scattering light.
→ The higher the filler loading, the worse the contrast. What should be jet black reads as murky gray to both the human eye and the scanner.

Once we identified the root cause, the path to a solution became clear — matching laser parameters precisely to the material composition to maximize carbonization depth while compensating for the reflectivity.

The result? Sharp, high-contrast marks. QR codes that scan first time, every time.

If your laser marking results aren't meeting spec — especially on white or light-colored plastics — the answer often isn't "more power." It's understanding what's inside your material.

Happy to discuss. Drop a comment or send me a message.

#LaserMarking #LaserEngraving #Plastics #Manufacturing #QualityControl #Traceability #QRCode #PCMaterial

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