ASA is often described as an outdoor version of ABS, and Prusa calls it a successor to ABS. The two print in similar conditions and can both be smoothed with acetone, so the choice usually comes down to sunlight, impact loads and how much warping and odor you can manage.
For like-for-like numbers, this page uses Polymaker's PolyLite ABS and PolyLite ASA data sheets, which share the same ISO test methods and specimen print settings. Prusa's material guides add printing settings, UV notes and safety guidance. Other brands and colors will vary.
ABS and ASA side by side
| Property | ABS | ASA |
|---|---|---|
| Nozzle temperature | 245–265 °C (PolyLite ABS); Prusa: 255 °C | 230–260 °C (PolyLite ASA); Prusa: 260 °C |
| Bed temperature | 90–100 °C (PolyLite ABS); Prusa: 100 °C | 75–95 °C (PolyLite ASA); Prusa: 105 °C first layer, 110 °C after |
| Enclosure | Needed (Polymaker); Prusa says the printer should be enclosed | Needed (Polymaker); Prusa says needed for large parts |
| Heat deflection, ISO 75 (1.8 / 0.45 MPa) | 98 °C / 100 °C | 100 °C / 103 °C |
| Vicat softening, ISO 306 | 104 °C | 105 °C |
| Tensile strength, ISO 527 (X-Y / Z) | 33.4 / 29.7 MPa | 43.8 / 32 MPa |
| Elongation at break (X-Y / Z) | 17.9% / 3.1% | 6.7% / 1.65% |
| Notched Charpy impact, ISO 179 | 18.0 kJ/m² (X-Y) | 10.3 kJ/m² (X-Y), 6.7 kJ/m² (Z) |
| UV and outdoor use | Prusa: no UV resistance; yellows and becomes brittle outdoors | Prusa: high UV resistance, suited to outdoor parts; Polymaker cites improved weather resistance |
| Warping | Prusa: significant warping; parts shrink about 1–2% | Prusa: significant warping, but less than ABS |
| Fumes and ventilation | Prusa: potentially dangerous styrene fumes; ventilate | Prusa: potentially dangerous styrene fumes; ventilate; smells less than ABS |
| Drying | 70 °C for 6 h (Polymaker) | 70 °C for 7 h (Polymaker); Prusa lists 80 °C for 4 h for Prusament ASA |
Property values come from Polymaker's PolyLite ABS and PolyLite ASA technical data sheets (same ISO test methods; specimens printed at 260 °C in a 90 °C environment), with printing and UV guidance from Prusa's ABS, ASA and drying articles.
Sunlight and weather
UV exposure is the main reason to pick ASA. Prusa lists high UV resistance as an ASA strength and recommends it for outdoor parts, while its ABS article says ABS has no UV resistance, unlike ASA, and that outdoor ABS parts yellow and become more brittle over time. Polymaker describes PolyLite ASA as an alternative to ABS with improved weather resistance, though its data sheet gives no weathering test figures.
For a part that stays indoors, this difference matters much less, and the other properties below decide the choice.
Heat and mechanical data
Heat performance is close. Polymaker lists heat deflection temperatures of 98 °C for PolyLite ABS and 100 °C for PolyLite ASA at 1.8 MPa, with Vicat points one degree apart. Prusa gives ASA a temperature resistance of up to 93 °C.
The mechanical data split. PolyLite ASA has the higher tensile strength (43.8 MPa in-plane against 33.4 MPa) and slightly higher stiffness. PolyLite ABS stretches much further before breaking (17.9% against 6.7% in-plane) and has the higher notched Charpy value, 18.0 kJ/m² against 10.3 kJ/m². That suggests ABS for parts that must survive impacts and ASA where steady tension matters, but Polymaker presents these as comparison values, so a test print of the real part is the better guide.
Printing, warping and fumes
Both materials need care with warping. Prusa says ASA warps less than ABS but still lists significant warping as its main drawback, and recommends a bed of at least 100 °C for both. Polymaker lists an enclosure as needed for both grades, while Prusa says ASA needs one mainly for large parts and suggests the draft shield setting when no enclosure is available.
Prusa warns that both release potentially dangerous styrene fumes and recommends a well-ventilated room. It notes ASA smells less than ABS. Prusa also says that printing a lot of ASA in an unventilated enclosure can, over time, deform the printer's own plastic parts, such as the fan shroud.
Finishing and moisture
Prusa notes that both materials can be smoothed and glued with acetone and sanded before smoothing. Prusa describes ASA as partially hygroscopic. Polymaker recommends drying PolyLite ABS at 70 °C for 6 hours and PolyLite ASA at 70 °C for 7 hours; Prusa's own table lists 80 °C for 4 hours for Prusament ASA, so use the figures for your brand.
Which should you choose?
Choose ABS if…
- The part stays indoors, so UV resistance is not a factor.
- Impact toughness matters, given PolyLite ABS's higher notched Charpy value and elongation.
- You already have tuned ABS profiles and a ventilated enclosure.
- The part will be acetone smoothed and used indoors.
Choose ASA if…
- The part will be outdoors or in sunlight, where Prusa rates ASA's UV resistance highly.
- You want somewhat less warping and odor than ABS, as Prusa describes.
- Steady tensile load matters, given PolyLite ASA's higher tensile strength.
- You need roughly ABS-level heat resistance in a weather-exposed housing or cover.
Common questions
Is ASA just UV-resistant ABS?
Prusa describes ASA as a successor to ABS with better UV resistance, less warping and less smell. The data sheets show other differences too: in Polymaker's data ASA has higher tensile strength but lower impact strength and elongation than ABS.
Does ASA need an enclosure?
Polymaker lists an enclosure as needed for PolyLite ASA. Prusa says one is needed for large parts and suggests the draft shield setting otherwise.
Which handles more heat, ABS or ASA?
They are close. Polymaker lists heat deflection temperatures of 98 °C for PolyLite ABS and 100 °C for PolyLite ASA at 1.8 MPa.
Sources
- PolyLite ABS technical data sheet (V5.5) Polymaker · Checked 2026-11-02
- PolyLite ASA technical data sheet Polymaker · Checked 2026-11-02
- ABS Prusa Research · Checked 2026-10-15
- ASA Prusa Research · Checked 2026-10-15
- Drying filament Prusa Research · Checked 2026-10-15
- Enclosure guidepost Prusa Research · Checked 2026-10-16
This comparison summarizes the cited documentation; it is not a lab test. Properties vary by brand, grade, print settings and orientation, so check the data sheet for the exact product you buy.