ASA gets described as ABS’s outdoor-durable sibling often enough that it is easy to assume the two are nearly the same material with a different name. Chemically, they are close. The practical difference that actually matters when picking between them is narrow and specific: what happens to the part after months of sun exposure, not how it prints or how strong it is fresh off the bed.
Chemically close cousins
ABS is acrylonitrile butadiene styrene; ASA swaps the butadiene rubber component for an acrylate rubber, according to Polymaker’s material documentation. That one substitution is the entire reason ASA resists ultraviolet light and weathering far better than ABS does, since the butadiene component in ABS is the part that breaks down under UV exposure. Everything else about the two polymers, the styrene backbone, the general stiffness and heat behavior, stays broadly similar.
Printing behavior is nearly identical
ABS and ASA print in overlapping ranges: ABS typically runs 230 to 255 degC at the nozzle with a bed around 95 to 110 degC, and ASA runs a little hotter, commonly 240 to 260 degC, with a similar bed range. Both benefit from an enclosure to control warping and both release fumes that call for real ventilation, covered in more detail in the PLA vs ABS guide. Community reports on whether ASA warps more or less than ABS in practice do not fully agree, so do not expect switching from one to the other to meaningfully change how much enclosure and bed prep your printer needs.
UV and weathering is the actual gap
Left outside, ABS chalks, yellows, and turns brittle within a season or two of steady sun exposure. ASA was built specifically to resist that: Polymaker’s own two-year outdoor aging test on their ASA showed a color change value under 2.5, and a separate accelerated aging test equivalent to roughly 8000 kJ/m2 of UV exposure still showed only minimal tensile strength loss. That is the entire case for ASA in one comparison: it holds its color and mechanical properties outdoors for years in conditions that visibly degrade ABS within months.
Heat resistance and strength are close enough not to decide it
Heat deflection figures for the two materials overlap more than they differ. ABS typically holds up to somewhere around 90 to 100 degC, and Prusament’s own data sheet for ASA lists a heat deflection temperature of 86 to 96 degC depending on test load, essentially the same range. Tensile strength figures likewise sit in the same rough neighborhood across brands for both materials. Neither one has a clear enough edge here to be the reason you pick it; that decision comes down to where the part will live.
Cost and availability tilt toward ABS
ASA typically costs more than ABS, commonly cited at around 10 percent or more depending on brand, and it comes in fewer colors and from fewer manufacturers since it is a smaller-volume product. That gap has narrowed as more budget ASA options have shown up, but ABS remains the cheaper, easier to find default of the two.
A practical choice
If the part lives outdoors, on a vehicle, or anywhere it will take direct sun for months at a time, spend the extra cost on ASA rather than finding out later how quickly ABS chalks and cracks in that environment. If the part stays indoors, gets painted or clear-coated, or only sees occasional sun through a window, plain ABS holds up fine and costs less. When in doubt, the deciding question is not how strong or how hot each material can run, it is how much direct outdoor time the finished part will actually see. If PETG is also on the table instead of ABS, the PETG vs ASA guide compares ASA against that alternative too. If PC is in consideration instead, the PC vs ABS comparison covers when the extra heat resistance is worth the harder print.