PLA is fine for decorative prints. But the moment your part needs to live outdoors, handle mechanical load, or survive inside a hot car, you’re choosing between PETG, ABS, and ASA. Each has a distinct personality — what prints easily, what warps, what lasts. Here’s how to match the filament to the job.
The Five-Second Decision Guide
If your part needs ONE thing above all else, here’s your filament:
- Temperature resistance: ASA (withstands 95°C before softening; PETG sags at 70°C, ABS at 85°C)
- Ease of printing: PETG (no enclosure needed, minimal warping, prints on any bed surface)
- UV/outdoor durability: ASA (designed for outdoor use; PETG yellows after 6-12 months, ABS degrades in weeks)
- Impact resistance: PETG (absorbs shock without cracking; ABS/ASA shatter under sharp impact)
- Chemical resistance: PETG (stands up to oils, mild acids, IPA; ABS dissolves in acetone)
- Post-processing: ABS (acetone vapor smoothing; PETG and ASA don’t smooth with solvents)
The Numbers That Matter
| Property | PETG | ABS | ASA | Why It Matters |
|---|---|---|---|---|
| Glass transition (Tg) | 70-75°C | 100-105°C | 105-110°C | When the part goes soft |
| Printing temperature | 230-250°C | 240-260°C | 250-265°C | All-metal hotend required for ABS/ASA |
| Bed temperature | 70-85°C | 100-110°C | 100-110°C | Enclosure mandatory for ABS/ASA above 5cm height |
| Tensile strength | 50 MPa | 40 MPa | 42 MPa | PETG is measurably stronger before yield |
| Flexural modulus | 2000 MPa | 2100 MPa | 2200 MPa | ASA is stiffest — less flex under load |
| Elongation at break | 15-20% | 10-15% | 10-15% | PETG stretches before breaking; ABS/ASA crack |
| UV resistance | Moderate (6-12 months) | Poor (weeks) | Excellent (years) | Outdoor parts: ASA wins decisively |
| Warping tendency | Low | High | High | PETG wins for ease of printing |
| Vapor smoothing | No | Yes (acetone) | No (ASA resists acetone) | ABS for cosmetic parts |
| Smell during printing | Minimal (sweet) | Strong (styrene) | Strong (styrene) | Ventilation required for ABS/ASA |
| Density | 1.27 g/cm³ | 1.04 g/cm³ | 1.07 g/cm³ | ABS/ASA parts are ~17% lighter |
| Cost per kg | $18-25 | $15-22 | $22-30 | ABS is budget; ASA carries a premium |
Real-World Application Mapping
PETG: Drone mounts, camera brackets, GoPro cases, battery straps, tool organizers, printer parts (not near hotend). The impact resistance means a TPU-printed GoPro mount that flexes can be replaced with PETG that snaps on securely and survives crashes. It’s the go-to material for FPV accessories as discussed in our 3D printed drone parts guide.
ABS: Voron printer parts (designed for ABS), enclosure panels, functional prototypes that need vapor smoothing, budget mechanical parts. ABS is lighter than PETG and the vapor smoothing option means cosmetic parts look injection-molded. But the warping: anything taller than 5cm without an enclosure WILL lift from the bed at corners.
ASA: Outdoor brackets, drone antenna mounts, car interior parts, solar panel mounts, anything that lives in the sun. ASA is basically UV-stabilized ABS with slightly better temperature resistance. The higher cost per kg is justified if the part lives outdoors — PETG outdoors will yellow and embrittle within a year, and ABS outdoors becomes brittle in weeks.
What Creators Get Wrong About These Materials
Mistake #1: Printing ABS without an enclosure and blaming the filament. ABS warps because it shrinks 1.5-2% as it cools from 250°C to room temperature. Without an enclosure maintaining 45-60°C ambient, the part cools unevenly — top layers shrink while bottom layers are still warm. That differential shrinkage curls corners upward. An enclosure isn’t optional; it’s physics. Our enclosure DIY guide walks through building one that works.
Mistake #2: Assuming PETG can replace ABS in all applications. PETG is great for most things, but it softens at 70°C. Inside a car on a summer day (dashboard hits 80°C), PETG parts deform. Motor mounts near a hotend (60-80°C ambient in the enclosure) lose dimensional accuracy over time. When heat is involved, the 30°C gap between PETG and ABS/ASA glass transition temperatures becomes the only spec that matters.
Mistake #3: Not drying PETG and ABS/ASA before printing. PETG absorbs moisture faster than PLA — a spool left out for 48 hours in 50% humidity will pop and string. ABS and ASA absorb less but are printed at higher temperatures where any moisture turns to steam at the nozzle, creating surface bubbles and weak layer adhesion. Dry PETG at 65°C for 4-6 hours. Dry ABS/ASA at 80°C for 4 hours. Our filament dryer guide covers moisture effects in detail.
Mistake #4: Using the same bed surface for all three materials. PETG sticks aggressively to PEI — sometimes too aggressively, peeling the PEI coating off the steel sheet. Use a glue stick or hairspray as a release agent, or switch to a textured PEI sheet. ABS/ASA need the opposite: maximum adhesion. A smooth PEI sheet cleaned with IPA works, or ABS slurry (ABS dissolved in acetone) painted on glass. Different bed surface strategies for different materials.
⚠️ Safety Notice: ABS and ASA emit styrene fumes during printing — a known irritant and potential carcinogen with prolonged exposure. Always print ABS/ASA in a well-ventilated area with active filtration (HEPA + carbon) if printing indoors. Enclosures should be constructed from fire-resistant materials and equipped with thermal runaway protection. PETG fumes are significantly less hazardous but ventilation is still recommended for long print sessions.
CNC Kitchen’s material comparison testing covers real strength numbers:
Printing functional drone parts and need filament that won’t let you down? The eSUN PETG+ and eSUN ASA filaments at uavmodel.com offer consistent diameter tolerance (±0.03mm) and ship vacuum-sealed with desiccant — no drying required out of the box. Available in black, white, and gray.