ABS vs ASA: which filament should you print with
Quick answer
Print in ASA, such as Polymaker ASA ($24.49/kg) or OVERTURE ASA ($23.39/kg), for anything that will spend real time outdoors or in a car, since ASA holds its color and strength under UV exposure that turns plain ABS yellow and brittle within one season outside. Print plain ABS, such as SUNLU ABS ($17.99/kg), for indoor functional parts, since it is usually a little cheaper and prints with the same basic profile.
SUNLU ABS Filament 1.75mm,Black,1kg
indoor functional parts, enclosures, and anything you plan to acetone-smooth
| ABS | ASA | |
|---|---|---|
| UV resistance | Poor, yellows and gets brittle in sunlight | Good, holds color and strength outdoors |
| Warping tendency | High, needs a heated bed and draft-free space | High, same enclosure needs as ABS |
| Fumes at print temperature | Styrene and ultrafine particles | Styrene and ultrafine particles |
| Enclosure needed | Yes | Yes |
| Extraction needed | Yes, even with an enclosure | Yes, even with an enclosure |
| Acetone vapor smoothing | Yes, a common finishing technique | Yes, works similarly to ABS |
| Best use case | Indoor functional parts | Outdoor or UV-exposed parts |
Does ABS actually degrade in sunlight, or is that overstated?
It is a real and fairly fast effect, not a minor cosmetic issue. Plain ABS left outdoors or behind glass in direct sun will yellow and become noticeably more brittle within a single season of exposure, which matters for anything load-bearing like a mounting bracket or an outdoor enclosure. This is exactly the gap ASA was formulated to close: it is essentially ABS with real UV stabilizers added, so it keeps its color and mechanical properties far longer outdoors.
Do I need an enclosure for both ABS and ASA?
Yes, both filaments warp badly without one. Both shrink as they cool, and if the outer walls of a print cool faster than the inside, that uneven shrinkage pulls the print up off the bed at the corners or splits layers apart. An enclosure keeps the ambient temperature around the print more even, which is what actually controls warping, not the bed temperature alone.
Neither filament forgives an open, drafty room the way PLA does. If you are set up for PLA only, printing ABS or ASA without adding an enclosure will likely produce failed prints.
Is the smell from ABS and ASA actually dangerous, or just unpleasant?
It is a genuine air quality concern, not just an unpleasant smell. Both filaments emit styrene and ultrafine particles at typical printing temperatures, and these are the same category of concern as fumes from other heated plastics. This is exactly why an enclosure is not a complete solution on its own: sealing the print chamber for warping control also traps those fumes right where you are breathing, so extraction is needed in addition to the enclosure, not as a substitute for it.
Can I smooth ASA parts with acetone vapor the same way as ABS?
Yes, ASA responds to acetone vapor smoothing in essentially the same way ABS does, since they share the same base chemistry with ASA adding UV stabilizers on top. This makes ASA a reasonable choice even for parts you intend to finish smooth, since you get the UV resistance without giving up the finishing technique that made ABS popular for display pieces.
ASA
Polymaker ASA Filament 1.75mm Black 1KG, UV & Weather Resistant
outdoor brackets, automotive parts, and anything exposed to sun or weather
Both sides of this comparison
- ELEGOO
ELEGOO ABS 3D Printer Filament 1.75mm Black 1KG Strong Layer Adhesion
$16.99 Check pricePrices change often - Polymaker
Polymaker ABS Filament Black 1KG 1.75mm, Heat Resistant, Strength
$17.10 Check pricePrices change often
Safety
Common questions
Is ASA just ABS with a different name, or a different material entirely?
ASA is closely related to ABS, essentially ABS with added UV stabilizers, so its printing temperature, warping behavior and general mechanical properties are similar. The meaningful difference is UV resistance, where ASA holds its color and strength outdoors far longer than plain ABS.
Will ABS parts left outside eventually fail?
Left in direct sun or behind glass, ABS yellows and becomes brittle within roughly a season, and a brittle part is more likely to crack under load or impact than a fresh one. For anything staying outdoors long term, ASA is the more reliable choice.
Do I need extraction if I already have an enclosure for ABS or ASA?
Yes. An enclosure controls warping by keeping ambient temperature steady, but it also traps the styrene and ultrafine particles both filaments emit at temperature, so extraction is still needed to actually remove those fumes from the space you are in.
Which filament is cheaper, ABS or ASA?
ABS is typically a little cheaper per kilogram than ASA, since ASA includes additional UV-stabilizing additives in its formulation. The price gap is usually modest and worth paying whenever UV exposure is part of the part's use case.
Can I print ABS or ASA on a printer set up only for PLA?
Not reliably without changes. Both filaments need a heated bed, a warping-resistant enclosure or draft-free space, and generally a higher nozzle temperature than PLA. A printer running an open frame with no enclosure will likely see corner lifting and layer splitting on both materials.