ASA vs ABS: Which Is Better for Outdoor Prints?
Both ABS and ASA handle heat and impact well — but for anything going outside, ASA wins on UV resistance and weather durability. Here's a complete comparison with settings for both.
Use ASA for outdoor prints. Use ABS for indoor parts that need acetone smoothing.
ASA was specifically developed as an outdoor-rated alternative to ABS. It shares ABS's strength and heat resistance but adds UV stability and better weather resistance.
Side-by-Side Comparison
| Property | ABS | ASA |
|---|---|---|
| Heat resistance | ~100°C | ~100°C |
| UV resistance | Poor (yellows, becomes brittle) | Excellent |
| Weather resistance | Moderate | Very good |
| Impact resistance | Good | Good |
| Acetone smoothing | Yes | No (requires MEK or THF) |
| Print difficulty | Hard | Moderate |
| Enclosure needed? | Yes | Yes (strongly recommended) |
| Price | $15–22/kg | $18–25/kg |
| Fumes | Strong | Moderate |
Why ABS Fails Outdoors
ABS contains no UV stabilizers. When exposed to sunlight:
- UV radiation breaks down polymer chains
- Surface yellows and becomes chalky
- Part becomes brittle and prone to cracking
- Structural integrity degrades within months
Tests show ABS parts can lose 40–50% of their tensile strength after extended UV exposure. For outdoor hardware, plant pots, drone parts, or car exterior clips — this is unacceptable.
What Makes ASA UV-Stable
ASA (Acrylonitrile Styrene Acrylate) replaces the butadiene rubber component of ABS with an acrylate rubber. Acrylate bonds are much more resistant to UV degradation. Real-world outdoor ASA prints maintain their color and structural properties for 2–5 years in direct sunlight.
ASA Print Settings
ASA prints very similarly to ABS, with slightly more forgiving settings.
| Setting | Value |
|---|---|
| Nozzle temp | 240–260°C |
| Bed temp | 100–110°C |
| Fan speed | 0–10% (bridging only: 20%) |
| Print speed | 40–50mm/s |
| Enclosure | Strongly recommended |
Key differences from ABS:
- ASA can tolerate slightly more fan (5–10%) without delaminating
- ASA is slightly less prone to warping on large flat parts
- ASA tolerates a wider temperature range (240–260°C vs ABS 235–250°C)
Bed Adhesion for ASA
Same options as ABS:
- Textured PEI: Works well when hot; releases when cool
- Glass + ABS juice: ABS juice works for ASA too (use leftover ABS or ASA scraps dissolved in acetone)
- Garolite: Excellent adhesion for both ABS and ASA
- High-temp hairspray: Works in a pinch
When to Choose ABS Instead
The one area where ABS still wins: acetone smoothing.
Acetone vapor polishing gives ABS a near-injection-molded finish. ASA doesn't respond to acetone — you'd need MEK (methyl ethyl ketone) or THF, both of which are much harder to source and more hazardous to work with.
If you need a smooth finish on an indoor part (cosplay props, display models, models to paint), ABS + acetone smoothing is hard to beat.
Best ASA Filament Brands
| Brand | Notes |
|---|---|
| Polymaker ASA | Most recommended; great UV resistance |
| eSUN ASA | Good value, reliable |
| Bambu ASA | Excellent for Bambu printers |
| Prusament ASA | Premium quality, tight tolerances |
Bottom Line
| Use Case | Choose |
|---|---|
| Outdoor mounting hardware | ASA |
| Garden stakes, markers | ASA |
| Car exterior parts | ASA |
| Drone components (outdoors) | ASA |
| Indoor functional parts | ABS or PETG |
| Parts you want to acetone smooth | ABS |
| Anything heat-exposed indoors | Either |