Material Comparison

PETG vs ASA

Two functional filaments for parts that need to survive real-world conditions. One is easy to print, the other handles the outdoors better.

Last updated: March 2026

For a full side-by-side comparison of PETG, ASA, and 6 other materials, see our master comparison table:

Materials Comparison Table
When to use
PETG

PETG is the low-friction path to functional parts. It prints without an enclosure, emits minimal fumes, and works on any printer with an all-metal hotend and heated bed.[1] The glass transition temperature sits around 80 °C, which is enough for most indoor mechanical applications — brackets, tool holders, electronics housings, cable management clips. It handles impact well, flexing slightly under load instead of shattering like PLA.

The downsides are well-documented: PETG strings like crazy, sticks too aggressively to smooth PEI, and does not hold up as well under prolonged UV exposure as ASA does. It also has a glossy finish that shows fingerprints and scratches.

Ideal for: indoor functional parts, mechanical brackets, electronics enclosures, tool holders, and anything that needs to be tougher than PLA without the hassle of an enclosure.

Community tip: Use a textured PEI sheet for PETG. On smooth PEI, PETG bonds so aggressively it can rip chunks off your build plate. A thin layer of glue stick acts as a release agent, not an adhesion promoter.
Browse PETG Deals Best Value PETG Guide
When to use
ASA

ASA exists for one reason: outdoor durability. It is effectively ABS with UV stabilizers baked in, giving it excellent resistance to sun, rain, and temperature swings.[2] The glass transition temperature is around 100 °C, well above PETG, meaning ASA parts survive inside a hot car or in direct summer sun without deforming. It also has a matte finish that looks more professional and hides layer lines better than PETG's gloss.

The catch is that ASA demands an enclosed printer. It warps badly in open air, even worse than ABS. It also emits styrene fumes during printing, so you need active ventilation — a carbon-filtered enclosure or a fan exhausting to a window.[3] Color selection is narrower than PETG, and it costs slightly more per kilogram.

Ideal for: outdoor enclosures, garden fixtures, automotive parts, signage, camera mounts, anything that lives in direct sunlight year-round.

Community tip: Print ASA in a heated enclosure at 40-60 °C ambient. Use a brim or raft on large flat parts. If you are seeing layer splits, raise your hotend temp by 5 °C and slow down — ASA needs more heat and time than PETG.
Browse ASA Deals Best Value ASA Guide
The community verdict

Use PETG for indoor functional parts. Use ASA when the part lives outside. That is the consistent advice on r/3Dprinting and the Voron/Bambu forums. PETG is the easier material by a wide margin — no enclosure, no fumes, fewer failed prints. But if your part needs to survive UV exposure for months or years, PETG will yellow and become brittle while ASA holds up.

If you already own an enclosed printer (Bambu X1C, Voron, Prusa with enclosure kit), ASA is a natural step up from PETG for outdoor projects. If you are printing on an open-frame machine, PETG is the practical choice — fighting ASA warping without an enclosure is not worth the trouble.

One more thing: if your "outdoor" part is just a mailbox flag or a garden stake that you can reprint in 20 minutes, PETG is fine. Save ASA for parts where failure matters — weatherproof electronics housings, security camera mounts, outdoor sensor enclosures.

Frequently Asked Questions

Does ASA really need an enclosure?
Yes. ASA warps aggressively when exposed to drafts or temperature swings. An enclosure that maintains 40-60 °C ambient is practically required for anything taller than a few centimeters. Without one, expect curling corners and layer splits. PETG, by contrast, prints fine in the open.
Is ASA safe to print indoors?
ASA emits styrene fumes during printing, which are irritating and potentially harmful with prolonged exposure. You need active ventilation — either an enclosure with a carbon filter or printing near an open window with a fan exhausting air outside.[3] PETG emits far fewer volatile organic compounds and is considered safer for indoor use, though all filaments produce ultrafine particles.
Which is better for outdoor use, PETG or ASA?
ASA is the better choice for permanent outdoor parts. It has superior UV resistance and will not yellow or become brittle after months of sun exposure. PETG handles outdoor use reasonably well — better than PLA — but will degrade faster under sustained UV. For parts that live outside year-round, ASA is the clear winner.
Can I print ASA on a Bambu Lab or Prusa printer?
Yes. Any printer with an all-metal hotend, a heated bed reaching 100 °C, and an enclosure can print ASA. The Bambu Lab X1C and P1S both have enclosures and handle ASA well out of the box. Prusa MK4 can print ASA with the add-on enclosure. The Prusa MINI and Bambu A1 mini lack enclosures and are not recommended for ASA.
Does PETG string more than ASA?
Yes, PETG is notorious for stringing. It has a very wide temperature range where it remains viscous, making clean retractions harder. ASA strings less than PETG but more than PLA. For PETG, tuning retraction distance (4-6 mm bowden, 0.5-1 mm direct drive) and lowering temperature by 5 °C increments helps. Pressure advance also makes a noticeable difference.

References

  1. Prusa Knowledge Base — PETG. https://help.prusa3d.com/article/petg_2059
  2. Prusa Knowledge Base — ASA. https://help.prusa3d.com/article/asa_2035
  3. UL SPOT — Emissions from Desktop 3D Printers. https://spot.ul.com/3d-printing-emissions/