ASA vs ABS: Differences and When to Choose Each

ASA is often described as the successor to ABS. It prints at similar temperatures and warps in similar ways, but it resists sunlight, warps less and smells less. This page compares the two using Prusa's material guides and Prusament data. It is research from manufacturer documentation, not our own print tests, and the price gap is not covered because we could not verify a like-for-like pair.

The short answer

• Choose ASA for parts that live outdoors or in sunlight, or that sit in a warm place such as a car interior or near electronics.
• Choose ABS for indoor technical parts when you want a material that has been used for hobby printing for longer, and sunlight is not a concern.
• Both need an enclosure, ventilation and a hot bed. If you have an open-frame printer and want an easier tough material, read ABS vs PETG first.

ASA vs ABS side by side

Figures come from Prusa's ASA and ABS knowledge base articles, its filament material table and the Prusament ASA page. Brands differ, so the label on your spool takes priority.

UV resistance and outdoor use

This is the main reason to pay attention to ASA. Prusa says that, compared with ABS, ASA is more UV resistant, warps less and does not smell as much, and calls it suitable for outdoor use. For ABS, Prusa says parts used outdoors turn yellowish and more brittle over time. Prusament describes ASA as UV stable and says it will keep its toughness and not yellow for a long time. Typical outdoor jobs are garden fixtures, bike parts, signs and housings.

Heat resistance

Prusa gives ASA a temperature resistance of up to 93 °C and says Prusament ASA shows no deformation up to temperatures near 93 °C. Prusa's ABS page calls its high-temperature resistance good but gives no figure. Treat 93 °C as a ceiling and leave a margin for parts under load, and check the data sheet of the filament you buy.

Warping and printing conditions

Neither is easy. Prusa lists significant warping as the main disadvantage of ASA, caused by the temperature difference between the model and the room, and says an enclosure is necessary for large parts. For ABS it also lists significant warping and says an enclosure is required. Prusament notes that even with the bed at 110 °C, large ASA prints can shrink and warp and detach, though much less than ABS, and says an enclosure or a tall skirt helps.

Both materials share the same tactics: a bed of at least 100 °C, no drafts, a draft shield if you lack an enclosure, and ventilation without a draft around the print. Prusa also warns that printing a lot of either material in an unventilated enclosure can deform the fan shroud and extruder plastic parts. See enclosed vs open-frame printers for what an enclosure gives you, and ABS print settings. If your prints crack between layers, fix ABS cracking applies to ASA too.

Bed surface and finishing

Both can grip a smooth PEI sheet hard, so Prusa recommends a glue stick on the smooth or powder-coated PEI sheet for each. ASA sticks very well to Prusa's sheets; on glass, Prusa says it may need a layer of acetone with dissolved ASA or ABS. It warns against putting acetone or ABS and ASA juice on powder-coated sheets.

Finishing is almost identical. Both sand wet or dry, glue with acetone and smooth with acetone vapors to a glossy surface. Prusa says smoothed objects usually lose detail and sharp edges.

Safety

Prusa says both materials release potentially dangerous fumes during printing, so run them in a well-ventilated area and avoid creating a draft around the print. Prusament notes that ASA contains styrene and produces odors, though less than ABS. Follow the filament maker's guidance and Safety Data Sheet. Our 3D printer safety basics page gives general precautions.

Which should you pick?

For a wider look at material options, read PLA vs PETG vs ABS vs TPU, or PETG vs PLA if you do not need an enclosed printer.