Short answer: Very similar materials. ASA resists sunlight and weather; ABS is slightly cheaper and ideal indoors.
Side by side
| ABS | ASA | |
|---|---|---|
| Heat | About 95–100 °C (200–210 °F) | About 95–100 °C (200–210 °F) |
| Sunlight and weather | Yellows and weakens | Built to resist UV and weather |
| Toughness | Tough | Tough |
| Finish | Glossy; vapour-smooths well | Slightly matte |
| Cost | Lower | Slightly higher |
Choose ABS for
- Indoor heat-resistant parts
- Parts to be vapour-smoothed
Choose ASA for
- Anything that lives outdoors
- Car exterior parts, signs, and mounts
Still unsure? Find a local shop and ask which material they'd recommend for your part.