ASA is the outdoor filament that actually holds up — UV-stable, heat-resistant, and tougher than PETG in direct sunlight. The catch: it prints like ABS and warps if you rush it. Here's how to get it right the first time.
ASA — Acrylonitrile Styrene Acrylate — was developed as a direct answer to ABS's biggest weakness: ultraviolet degradation. ABS yellows, becomes brittle, and loses structural integrity within months of sustained outdoor exposure. ASA replaces the butadiene rubber phase in ABS with an acrylate-based rubber that is chemically resistant to UV radiation. The result is a material with almost identical mechanical properties to ABS, but with genuine long-term outdoor durability.
In practical terms, ASA parts left in full sun maintain colour and strength for three to five years rather than months. Automotive parts, marine accessories, garden fixtures, weatherproof enclosures, signs, and outdoor camera mounts are the canonical use cases — anywhere PETG's moderate UV resistance isn't enough and PLA would fail within weeks. If your print will live outside, ASA is almost always the correct choice.
The trade-off is that ASA inherits ABS's printing challenges. It warps, releases styrene fumes that require ventilation, and benefits strongly from an enclosure. On a Bambu Lab X1C or P1S with the heated chamber, those challenges are mostly solved out of the box. On open-frame machines, you'll need to work harder.
ASA is not a beginner material, but it's also not as finicky as its reputation suggests if your printer has an enclosure. The table below covers tested starting values for both Bambu Lab enclosed printers and general FDM machines. Tune from these baselines rather than starting from scratch.
| Setting | Recommended Value | Notes |
|---|---|---|
| Nozzle Temperature | 240–260°C | 245°C for most brands; 255°C for better layer bonding on structural parts |
| Bed Temperature | 90–110°C | 100°C is the reliable all-rounder; 90°C can work on textured PEI |
| Enclosure / Chamber Temp | 40–50°C ambient | Enclosure required; Bambu's heated chamber is ideal. Without it, expect warping on parts over 100mm |
| Print Speed | 40–80 mm/s | Slower = better layer bonding. Don't push ASA as hard as PETG |
| Part Cooling Fan | 0–20% | Minimal or off; active cooling causes warping and layer delamination |
| Retraction Distance | 0.5–1.5 mm | Direct drive: 0.6–1 mm. Bowden: 3–5 mm |
| Retraction Speed | 30–40 mm/s | Moderate speed; ASA is less prone to stringing than PETG |
| Brim | 8–12 mm recommended | Large brim significantly reduces corner lifting on big flat parts |
Bambu Lab's ASA filament comes with a pre-tuned profile that works well on the X1C and P1S — both have the heated chamber ASA needs. The A1 and A1 Mini lack a proper enclosure, which means full-chamber ASA printing is not practical on them. You can print small ASA parts (under 80mm in any direction) on A1/A1 Mini with a DIY enclosure or by boxing in the printer with a cardboard tent, but it's a workaround, not a proper solution.
These three materials cover the realistic outdoor printing options for FDM. PLA fails so quickly in sunlight it's not worth including. Here's how ASA, PETG, and ABS compare on the properties that actually matter for outdoor use cases. For a broader comparison including PLA, see our PLA vs PETG vs ASA guide.
| Property | ASA | PETG | ABS |
|---|---|---|---|
| UV Stability | Excellent (years) | Moderate (months) | Poor (weeks–months) |
| Heat Resistance (HDT) | ~100°C | ~80°C | ~98°C |
| Impact Strength | High | High | Moderate |
| Water Resistance | Excellent | Excellent | Good |
| Printing Difficulty | Hard (needs enclosure) | Moderate | Hard (fumes + warping) |
| Warping Tendency | High without enclosure | Low | Very high |
| Acetone Smoothing | Partial effect | No effect | Works well |
| Fume Safety | Requires ventilation | Low odour | Strong fumes |
Warping is ASA's defining challenge, and it comes from thermal differential: the outer edges of a print cool faster than the centre, creating internal stresses that curl the part off the bed. Every setting tweak for ASA ultimately reduces this differential. Understanding why helps you prioritise fixes.
Any ASA print over roughly 80mm in width needs a stable chamber temperature between 40–50°C to prevent corner lifting. Bambu Lab's X1C and P1S achieve this automatically. For open-frame printers, a proper enclosure (like a Bambu Lab retrofit or a commercial enclosure kit) is the single most impactful upgrade. A cardboard box tent reduces drafts and retains some heat — it's not ideal but meaningfully reduces failures on smaller parts.
Textured PEI is the gold standard for ASA. At 100°C bed temperature, ASA bonds aggressively enough to survive the full print without a brim on medium parts. For larger prints, add a 10–12mm brim. Never use smooth Cool Plate — ASA bonds unevenly and the high bed temperature risks permanent damage to the plate. See our complete bed adhesion guide for surface-by-surface comparisons.
If you're having persistent adhesion issues: clean the textured PEI with IPA, increase bed temperature to 105°C for the first three layers, and use the "Bed Levelling" calibration in OrcaSlicer before each ASA print. Even a 0.05mm variation in Z-offset causes the first layer to fail.
Thin, flat parts with long unsupported edges are ASA's enemy. If you have a 200mm-long flat bracket, the corners will lift unless you add a brim and/or print diagonally to reduce the effective unsupported length. Parts with a natural chamfer at the base — 45° angles rather than sharp 90° corners meeting the bed — lift far less because stress concentrates at the tip rather than across a sharp edge. Design for this where possible.
ASA is hygroscopic — it absorbs moisture from the air within days of being opened. Wet ASA produces a distinctive crackling or popping from the nozzle, rough bubbly surface texture, and reduced layer bonding strength. Dry ASA at 70–75°C for 4–6 hours before any critical print. Unlike PETG, which dries at 65°C, ASA needs slightly higher temperature to drive out absorbed water efficiently. A dedicated filament dryer running during a long print also prevents re-absorption if your humidity is high.
ASA quality varies considerably between brands. Poor-quality ASA has inconsistent diameter, higher residual moisture, and inadequate UV stabiliser concentration — meaning it may warp in the sun almost as fast as ABS despite carrying an ASA label. These are the brands with consistent results:
| Brand / Product | Best For | Price | Notes |
|---|---|---|---|
| Bambu Lab ASA | Bambu X1C/P1S users, AMS printing | ~€24/kg | Pre-tuned profiles, consistent diameter, AMS-compatible. Limited colour range but reliable every time |
| eSUN eASA | Functional outdoor parts, colour variety | ~€19/kg | Good UV stabilisation, wide colour range including UV-fluorescent options, reliable diameter |
| 3DJake ASA | Budget-conscious EU buyers | ~€15/kg | Solid performance for the price, fast EU delivery, good for first ASA experiments |
| Extrudr ASA NX2 | Maximum outdoor performance | ~€32/kg | Enhanced UV package, excellent mechanical properties, used in professional outdoor signage |
| Prusament ASA | Precision, tight tolerances | ~€28/kg | ±0.02mm diameter, documented batch testing, great surface finish |
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