PETG (Polyethylene Terephthalate Glycol)

Physical properties

Laser processing

Fumes contain minimal traces of non-hazardous organic compounds at normal processing volumes. PETG is considered one of the safest alternatives to PVC for laser cutting. Does not release chlorine or acidic compounds. Standard extraction is sufficient but always recommended.

CO₂: Excellent behaviour with CO2 laser. Thin thicknesses (1–3mm) cut extremely cleanly, with smooth, transparent edges. Adjust air and speed carefully to avoid flare-ups. PETG produces one of the cleanest laser cuts among common thermoplastics, with minimal edge melting.

Diode: Cutting limited to dark or coloured variants. The blue diode passes straight through transparent PETG without affecting it. Only black or heavily pigmented PETG sheets can be cut with a diode laser.

Fiber: Not applicable.

CNC / milling processing

Good CNC machinability. With a higher Tg than PLA (~80°C), it resists friction-generated heat better but still requires sharp single-flute bits and efficient chip evacuation. Use moderate RPM (16,000–20,000) and generous feed rates. Compressed air cooling prevents chip re-welding.

3D printing

Plotter and thermoforming

Post-processing

Sanding: Tough polymer: tends to create filaments rather than clean dust when dry-sanded. Wet-sand with progressive grits. Grit sequence: 180 → 240 → 320. For 3D printed parts, use filler primer before sanding for best results.

Primer: mandatory. If 3D-printed via FDM, requires filler primer to cover horizontal layer lines before acrylic painting. PETG has good paint adhesion compared to other thermoplastics. Standard plastic primer spray works well.

Gluing: Highly resistant to chemical solvents (does not react to acetone, unlike ABS). For structural bonding, prefer polyurethane adhesives or filled cyanoacrylates. Epoxy adhesives work but require surface roughening for mechanical grip.

Seasoning: PETG absorbs less moisture than PLA or PA. For 3D printing filament, drying at 65°C for 4 hours is sufficient. Store in a sealed container with desiccant for best print quality.

Over time: Excellent weather and moisture resistance. Very stable for long-term outdoor use compared to PLA. PETG does not become brittle over time and maintains impact resistance for years. Slightly less UV-resistant than PET; prolonged direct sunlight causes gradual yellowing.

Common defects

• Stringing (fine thread formation between moves) in 3D printing if the filament has been exposed to ambient humidity
• Very strong adhesion to glass printer beds — can tear glass pieces if removed without release agent

Safety

Very stable and safe thermoplastic polymer. Does not release corrosive acids. Excellent PVC substitute for transparent shaped applications. FDA-approved for food contact in many grades. Laser fumes are among the least harmful of common plastics.

Availability and formats

Commercial formats: filament 1.75mm, sheets 1–5mm

Related materials

Sources

• ISO 11357 — Plastics thermal analysis
• FDA Food Contact Substance Notification