ABS vs ASA

Indoor vs outdoor.
Similar plastics.
UV makes the difference.

ABS is the workhorse injection molding thermoplastic — durable, affordable, paintable. ASA is ABS's UV-stable sibling — same mechanical properties, much better outdoor performance. For outdoor applications, the cost premium is worth it.

Get a Quote DFM guide

01 · At a glance

Side-by-side summary.

Option A

ABS

Acrylonitrile butadiene styrene. Standard injection molding thermoplastic. Impact resistant, machinable, paintable. Yellows and becomes brittle under UV. Indoor use default.

Option B

ASA (Luran S)

Acrylonitrile styrene acrylate. Same mechanical properties as ABS but excellent UV resistance. 10+ year outdoor service without degradation. Automotive exterior standard.

02 · Detailed comparison

Feature-by-feature breakdown.

Attribute	ABS	ASA
Density	1.05 g/cc	1.07 g/cc
Tensile strength	43 MPa	40 MPa
Impact strength	Excellent (Izod 20-30 J/m)	Excellent (similar)
HDT (1.8 MPa)	85-100°C	90-100°C
UV stability	Poor (yellows, cracks)	Excellent (10+ years outdoor)
Chemical resistance	Moderate (attacked by aromatics)	Similar to ABS
Paint adhesion	Excellent	Excellent
Cost per kg raw	$2-4	$3-5
Cost premium (vs ABS)	Reference	+20-40%
Injection moldability	Excellent	Excellent
3D printable	Yes (FDM standard)	Yes (FDM, specialty)
Typical applications	Electronics, interior, toys	Automotive exterior, siding

03 · Decision guide

When to choose each.

Choose ABS when:

Indoor consumer electronics housings
Interior automotive trim
Toys and household products
Cost-sensitive applications
Painted parts (UV protection from paint)
Applications where UV exposure is limited

Choose ASA (Luran S) when:

Automotive exterior trim (unpainted)
Outdoor housings (electronics, equipment)
Siding and architectural panels
Garden/outdoor products
Signage exposed to sunlight
RV and marine exterior components

FAQ

Common questions.

ABS contains butadiene rubber for impact strength. Butadiene has double bonds (C=C) that are attacked by UV photons. UV oxidation: breaks molecular bonds, yellows color, increases brittleness, initiates surface cracks. Within 1-2 years outdoor: visible yellowing. 3-5 years: brittle, cracking. ASA replaces butadiene with acrylic elastomer (saturated, no double bonds) — UV-stable chemistry. Same impact performance, radically different UV behavior.

Paint provides UV protection for ABS underneath. For painted parts, standard ABS is adequate — paint blocks UV from reaching polymer. Many painted automotive interior and consumer products use ABS with UV protection from paint. Problem arises if paint scratches or chips — exposed ABS then degrades rapidly. For unpainted outdoor or for paint reliability concerns: ASA.

ASA filament available for FDM 3D printing. Same print parameters as ABS (enclosed chamber, 230-260°C nozzle, 100°C bed). Better UV resistance makes ASA popular for outdoor 3D printed parts — automotive accessories, garden hardware, outdoor enclosures. Cost premium over ABS filament 30-50%. For outdoor FDM applications, ASA is generally preferred choice.

ASA is the automotive industry standard for exterior trim: grilles, side mirrors, wheel arch flares, bumper trim, fender liners. Both painted and unpainted parts. Premium cost over ABS justified by 10+ year outdoor durability required for warranty. Major automotive producers specify ASA (often by trade names BASF Luran S or Ineos Styrolution Luran). For aftermarket accessories, ASA preferred.

Both ABS and ASA: moderate chemical resistance. Attacked by: aromatic hydrocarbons (toluene, xylene), chlorinated solvents, some alcohols in prolonged contact. Resistant to: water, weak acids, weak bases, oils, alcohols (brief contact). For chemical-contact applications, neither is ideal — consider PP, HDPE, or PPS instead. For general exposure, both acceptable.

ABS outdoor: yellows significantly within 1-2 years. Light colors (white, cream) show yellowing dramatically. Dark colors (black, gray) mask yellowing somewhat but still fade. ASA outdoor: maintains color 10+ years. Pigmented ASA maintains color even in light shades. For color-critical outdoor applications: ASA required. Dark-painted exterior: ABS + paint adequate if paint is UV-stable.