ABS and ASA — the complete guide
ABS is the original engineering plastic of 3D printing — tough, heat-resistant, and the same material as Lego. ASA is its UV-stable sibling, designed for outdoor use. Both warp badly without an enclosure, both off-gas styrene that you shouldn't breathe, and both reward proper temperature management with parts that hold up in cars, in sun, and under load.
Nozzle 240–260 °C, bed 100 °C, fan 0–25%, enclosure mandatory above ~80 mm tall parts. Vent the enclosure to outside — ABS/ASA fumes are unpleasant and potentially irritating. Use glue stick or ABS slurry on the bed. ASA for outdoor parts, ABS for indoor mechanical or acetone smoothing.
ABS vs ASA — what's the difference?
Both are styrene-based copolymers from the same chemical family:
- ABS = Acrylonitrile Butadiene Styrene. The original. Same material as Lego bricks and most automotive interior trim.
- ASA = Acrylonitrile Styrene Acrylate. Replaces the butadiene rubber with acrylic rubber, making it UV-stable.
For 3D printing purposes they behave nearly identically — same settings, same warping, same fume profile. Pick ASA for anything outdoors; ABS for indoor parts, acetone smoothing, or where cost matters (ABS is slightly cheaper).
Recommended print settings
| Setting | ABS | ASA |
|---|---|---|
| Nozzle temperature | 235–255 °C | 240–260 °C |
| First-layer temperature | 250 °C | 255 °C |
| Bed temperature | 95–110 °C | 100–110 °C |
| Enclosure temperature | 40–55 °C | 40–55 °C |
| Print speed | 40–60 mm/s | 40–60 mm/s |
| Part cooling fan | 0% (layers 1–5); 15–25% after | Same |
| Retraction | 0.6–1.5 mm (direct), 4–5 mm (Bowden) | Same |
| Bed surface | Smooth PEI + glue stick, or ABS slurry on glass | Same; textured PEI works without glue |
| Brim | 8–10 mm | 8–10 mm |
| Drying | 70 °C / 4 hours if showing symptoms | Same |
Enclosure: required, vented
Without an enclosed, warm chamber, ABS and ASA warp on anything larger than a small calibration cube. The enclosure does two things:
- Raises ambient temperature to 35–55 °C, reducing the cooling differential that causes warping.
- Blocks drafts — even a fan running on the other side of the room causes localized cooling that lifts corners.
Enclosure options
- Factory-enclosed printers: Bambu X1C / P1S / H2D, Prusa CORE One, Qidi X-CF Pro, Snapmaker.
- Aftermarket fabric enclosures: Creality and Anycubic sell $60 fabric tents for open-frame printers.
- DIY: IKEA Lack table hack, plywood box, or repurposed grow tent.
- Don't try to print ABS open-frame on anything bigger than ~50 mm tall — you'll waste filament.
Ventilation matters
Both are respiratory irritants. Print enclosed and vented to outdoors, in a garage, or under a fume hood. A HEPA-only filter doesn't remove gaseous VOCs — you need activated carbon or actual outdoor ventilation. See the 3D printing safety guide.
Bed adhesion for warpy materials
Three options that work:
- Smooth PEI + glue stick (Pritt, Magigoo, 3DLac). Reapply every 3–5 prints.
- ABS slurry on glass — acetone with dissolved ABS scraps painted thin. Classic Stratasys-grade adhesion.
- Textured PEI — usually works without adhesive, but glue stick helps for tall ABS prints.
Plus: a wide brim (8–10 mm), mouse-ears at the corners, and bed temp at the top of the recommended range.
Fighting warping
See the dedicated warping guide, but for ABS/ASA specifically:
- Print enclosed (mandatory above ~80 mm tall).
- Bed at 100–110 °C.
- Wide brim (8–10 mm) with 0.1 mm separation gap so it peels.
- Part-cooling fan at 0–25% (never 100%).
- Round bottom corners on your CAD (1 mm fillet) so there are no sharp corners to lift.
- Orient the largest flat face on the bed.
- If still warping: thicker first layer (0.25 mm) and slower first-layer speed (15 mm/s).
Strengths
- Heat resistant: ~100 °C HDT. Survives a car interior in summer.
- Tough: high impact resistance; bends rather than snaps.
- Acetone-smoothable (ABS only) — vapor smoothing produces injection-molded-quality surfaces.
- Easy to glue: ABS-to-ABS bonds with acetone. ASA needs MEK or specific ASA cement.
- UV stable (ASA): outdoor parts last years without yellowing or embrittling.
- Cheap: $20–$30/kg, comparable to PLA.
Weaknesses
- Warps badly without enclosure.
- Off-gasses styrene and VOCs — not safe to print in living spaces without ventilation.
- UV degrades ABS within months outdoors — use ASA instead.
- Hygroscopic: dry before printing (less critical than nylon, more than PLA).
- Visible layer lines: ABS shows layer aliasing more than PETG.
- Slight shrinkage: design parts ~0.5–1% larger than target dimensions.
Mechanical properties (typical)
| Property | ABS | ASA |
|---|---|---|
| Tensile strength | 30–40 MPa | 35–45 MPa |
| Flexural strength | 60–80 MPa | 65–85 MPa |
| Impact (Izod, notched) | 10–25 kJ/m² | 10–20 kJ/m² |
| HDT (heat deflection) | ~95 °C | ~95 °C |
| UV resistance | Poor | Excellent |
| Density | 1.04 g/cm³ | 1.07 g/cm³ |
Acetone smoothing (ABS only)
One of ABS's unique party tricks: acetone vapor dissolves the surface layer, smoothing layer lines into a glossy finish.
- Use a sealed glass container (jar, big tupperware).
- Place paper towels saturated with pure acetone around the inside, away from the print.
- Suspend the print on a metal mesh in the centre.
- Seal and leave for 10–30 minutes. Inspect every 5–10 min.
- Remove and let cure 24+ hours before handling — the surface is soft until the acetone fully evaporates.
Do this outdoors or in a fume hood. No ignition sources. Don't seal in a metal container that could rust into the seal — the resulting pressure-pop is not fun.
When to choose ABS or ASA
- Car interior parts (dashboard clips, brackets) — ABS or ASA.
- Outdoor parts — ASA.
- Mechanical enclosures with heat exposure — either.
- Snap-fits for repeated use — either.
- Smooth-finish display pieces — ABS for acetone smoothing.
- RC parts — ASA for outdoor RC; ABS for indoor.
Avoid for: parts you'll print without an enclosure, indoor spaces without ventilation, fine miniatures (use PLA), anything bigger than your enclosure's stable warm volume.
Related articles
Sources & further reading
- Prusa Knowledge Base — ABS material guide
- Bambu Lab Wiki — Bambu ABS documentation
- Bambu Lab Wiki — Printing Tips for Engineering materials