ABS and ASA are close relatives. Both need heat, both warp, both want an enclosure, and both make parts that survive temperatures where PLA gives up. Choosing between them is simpler than the specification sheets suggest.
The short answer
Sunlight decides it. ASA holds its colour and surface under UV. ABS yellows, chalks, and gets brittle after a season outdoors. If the part lives outside or behind a car windscreen, print ASA. If it lives in a drawer, ABS is cheaper and does the same job.
Printing difficulty
They are nearly the same to run:
- Nozzle around 240 to 270 °C
- Bed 80 to 100 °C
- Chamber 45 to 60 °C
- Part cooling off or very low
Both shrink as they cool, which is why an enclosure matters. Without one, tall parts split at a layer line partway up, and large flat parts lift at the corners. A cardboard box over an open frame printer is a genuine improvement over nothing.
ASA is marginally more forgiving in practice. It cracks slightly less often mid print and smells less aggressive, though both want ventilation.
Strength and heat
Mechanically the two are close enough that the choice rarely comes down to numbers. Both stay usable well above the temperature at which PLA starts creeping, both take impacts without shattering, and both drill and tap cleanly.
ABS has one advantage that survives from its long history: acetone vapour smoothing. Expose an ABS part to acetone vapour and the surface melts into a glossy, near injection moulded finish. ASA responds to acetone too but less predictably.
UV and weather
This is the whole argument.
| Property | ABS | ASA |
|---|---|---|
| UV stability | Poor, yellows and chalks | Good, holds colour for years |
| Water resistance | Good | Good |
| Colour fade outdoors | Noticeable in one summer | Minimal |
| Typical price | Slightly cheaper | Slightly higher |
The acrylic component in ASA is what buys the UV stability. Everything else about the material is essentially ABS.
What to print in each
ABS: enclosures for indoor electronics, tool handles, anything you plan to vapour smooth, prototypes that need heat resistance on a budget.
ASA: garden and fence brackets, car interior clips, sensor housings, letterbox parts, anything mounted on a south facing wall.
When to skip both
If your printer has no enclosure and no easy way to improvise one, print PETG instead. PETG holds shape to around 80 °C, resists weather reasonably well, and prints on an open frame without cracking. You lose the top of the temperature range and the vapour smoothing, and you gain a print that actually finishes.
For parts that see both heat and mechanical load, a carbon filled nylon is the next step up, with the drying and hardened nozzle requirements that come with it.
Annealing
Both materials benefit from a post print bake, typically 80 to 90 °C for six to twelve hours. It relieves the internal stress that printing leaves behind, which reduces later cracking in parts that get hot in service. Expect a small amount of shrinkage, so test on a spare part before annealing anything that has to fit.