Key takeaways
- The mechanical figures differ by under 10 %. Don't choose on the mechanical data table.
- ABS loses toughness and chalks after a few months of direct sun. ASA was made not to.
- Both need an enclosure and extraction. ASA is not easier to print than ABS.
- ABS dissolves in acetone, so parts can be solvent-welded — the one valid reason to choose it for indoor parts.
This is one of the few material comparisons with a short answer. The two are so alike that if you handed me two parts printed indoors, I couldn't tell them apart by hand. Leave them on a Saigon rooftop for three months and you can tell from across the street.
Where the difference lies
ABS is a copolymer of acrylonitrile, butadiene and styrene. The butadiene forms a rubber phase dispersed through the matrix — that is what gives ABS its notched impact strength of 18.0 kJ/m² on the Polymaker TDS, more than five times PolyLite PLA.
The trouble is that butadiene has double bonds in its chain. Ultraviolet light carries enough energy to break exactly those bonds, and once the rubber phase is broken, ABS loses precisely what made it tough. The symptoms, in order: loss of gloss, colour shift, a chalky surface, then fine crazing. After that the part shatters when dropped instead of bouncing.
ASA replaces butadiene with an acrylate rubber — a saturated rubber with no double bonds to break. Everything else in the recipe stays the same. That is why the two data sheets are almost identical, and also why ASA costs more: acrylate monomer is more expensive than butadiene.
The numbers, side by side
| PolyLite ABS | Polymaker ASA | |
|---|---|---|
| Tensile strength | 33.4 MPa | 43.8 MPa |
| Elongation at break | 17.9 % | 6.7 % |
| Tensile modulus | 2,247 MPa | 2,379 MPa |
| Bending strength | 56.2 MPa | 73.4 MPa |
| HDT 0.45 MPa | 100 °C | 103 °C |
| Notched impact | 18.0 kJ/m² | 10.3 kJ/m² |
| Shrinkage | 0.8 % | 0.7 % |
| UV resistance | Poor | Good |
| Acetone bonding | Yes | Weaker |
| Relative price | ≈ 1.05× | ≈ 1.3× |
If the part can see the sky, the answer is ASA. Every other argument comes after that sentence.
Print settings: nearly identical
Starting settings
- ABS Core
- Nozzle 245–265 °C · bed 95–110 °C · chamber 45–55 °C · fan 0–20 % · dry 70 °C / 4 h
- ASA Core
- Nozzle 250–270 °C · bed 100–110 °C · chamber 50–60 °C · fan 0–15 % · dry 70 °C / 4 h
ASA wants about 5 °C more at both the nozzle and the chamber, and slightly less fan. Otherwise every rule is the same: an enclosure is mandatory for parts wider than about 80 mm, extraction is always mandatory, and both grip far better on a textured plate or a plate with adhesive.
Which one to choose
Decide by the part
- Outdoor mounts, sensor housings, signs
- ASA — there is no second option
- Parts in a car parked in the sun
- ASA — both heat and UV through the glass
- Indoor electronics housings near heat
- ABS — cheaper, and no UV to worry about
- Multi-piece parts solvent-welded together
- ABS — acetone dissolves the surface and cold-welds two pieces
- Vacuum-forming moulds, masters
- ABS — easy to sand and to smooth with acetone vapour
If the part has to go past 100 °C or take still more impact, both are out of road and the answer lies with polycarbonate and nylon. If your printer has no enclosure, read the substitution guide before buying any spool.
Frequently asked
Is ASA stronger than ABS?
Not exactly — it trades. On the Polymaker TDS, ASA is stronger in tension (43.8 vs 33.4 MPa) and bending (73.4 vs 56.2 MPa), but its notched impact is lower: 10.3 vs 18.0 kJ/m². In other words, ASA is stiffer and ABS is tougher. The real difference is still UV resistance: after a few months of direct sun, ABS loses most of its toughness and ASA doesn't.
Is ASA easier to print than ABS?
No. It needs about 5 °C more at the nozzle and in the chamber, shrinks about as much, and has the same enclosure and extraction requirements. People who say ASA is easier are usually comparing a dry spool of ASA with a wet spool of ABS.
Can I print ABS or ASA on an open-frame printer?
Small parts under about 80 mm sometimes survive. Larger parts warp at the corners or split between layers, because the lower layers cool and shrink faster than the top. An enclosure holding 45–60 °C fixes that; extraction remains a separate, mandatory requirement.
Can ASA be bonded with acetone?
Noticeably worse than ABS. The acrylate rubber phase doesn't dissolve in acetone the way butadiene does, so the bond is weaker and the surface won't vapour-smooth. For multi-piece ASA parts, use a two-part adhesive or design a mechanical joint.
Can PETG replace ASA for outdoor parts?
Only under a roof or for short-term use. PETG handles water well and UV moderately, but it yellows and loses toughness in prolonged direct sun, and its 73 °C heat deflection is too low for sun-exposed surfaces in a tropical climate.