Filament for Outdoor Use: UV, Heat and Weather

Who this guide is for

You're printing something that will live outside or on a sunny windowsill: a garden fitting, a hose clip, a mailbox flag, a sensor housing, a bike mount. Three things will act on it:

• Sun. UV light, which makers discuss in terms of fading, yellowing and brittleness.
• Heat. A dark part in direct sun, or a part in a parked car, can get much warmer than the air around it.
• Water. Rain, humidity and sprinklers, which matter for both the finished part and the spool before printing.

This guide collects what filament makers publish about each, material by material, and names the maker and product behind every claim. For heat, our heat deformation guide already compares each maker's HDT and Vicat figures with their test loads, so this page adds only figures that guide doesn't cover. If you've narrowed it to two materials, see ASA vs PETG or ABS vs ASA.

What makers say, material by material

The sections below give each maker's wording and any figures.

Can PLA be used outdoors?

Prusa is the most direct. Its PLA guide says PLA "is not suitable for technical and outdoor use," and that it "gets soft and deforms at temperatures over 60 °C" and "degrades under UV light." It lists "Low UV and temperature resistance" as a drawback. The Prusament PLA page says "The combination of being both low UV resistance and having low-temperature resistance means that it's not ideal for outdoor use."

Polymaker's PLA wiki page lists "Low Heat Resistance: Unsuitable for automotive or outdoor use without modifications." Our heat deformation guide covers Bambu Lab's "about 50 ℃" limit for PLA.

Polymaker's exception: Matte PLA for Production

Polymaker's wiki has a page titled "PLA Can Be Weather Resistant." It says "traditional PLA may degrade more quickly under prolonged sunlight or outdoor exposure," but that "specially engineered PLA variants can hold up much better." Its example is Polymaker's Matte PLA for Production, which it says "performs on par with ASA" in weather resistance testing.

The FAQ on the product's wiki page describes the test. Polymaker says it tested the effect of accelerated weathering on tensile strength, Young's modulus and Charpy impact strength:

• UV exposure to ISO 4892-3 (the FAQ writes "ISO 4892.3"), with UVA-340 lamps at 0.76 W/m² at 340 nm
• Cycles of 102 minutes of UV only and 18 minutes of water spray
• A black panel temperature of 63 ± 3 °C
• 60 days (720 cycles), which the FAQ calls "equivalent to ~3+ years," citing MICOM Laboratories and an acceleration factor of 21.5

The FAQ doesn't give the before-and-after results on that page. The claim covers that one Polymaker product, not PLA in general. It also doesn't change PLA's heat limits. Polymaker's weathering page notes that PLA "is well-known for having a relatively low heat resistance." A PLA part in hot sun can still soften, whatever its UV rating. If you're deciding between PLA and ASA for an outdoor part, see PLA vs ASA.

Is PETG good for outdoor use?

Makers agree that PETG suits outdoor and wet settings. They disagree on how well it holds up in long sun exposure.

• Prusa says PETG suits "mechanical parts for both indoor and outdoor use," and lists "Water and humidity resistant" as an advantage. Its guide says PETG parts suit "most exterior use (with temperatures below 80 °C)." The Prusament PETG page says "Because of the very good layer adhesion, the PETG prints are suitable for waterproof applications." Neither page makes a UV claim.
• Bambu Lab says PETG Basic's "strong resistance to water, UV, and temperature makes it a highly cost-effective option for outdoor applications," with garden labels as an example. Its PETG HF page goes further, citing "superior resistance to water, UV, and temperatures" and outdoor toys "that require long-term exposure."
• eSUN headlines its PETG with "Excellent Weather Resistance Withstands Sun and Rain Outdoors," and says it is "Durable Outdoors," that it "Retains Color Without Fading," and that it is "Rain- and Humidity-Resistant – Maintains Shape and Firmness."
• Polymaker's pages disagree with each other. The FAQ on its PETG product page says "PETG is UV and water-resistant, making it suitable for outdoor parts, though prolonged exposure may degrade some properties." Its wiki says PETG "withstands exposure to acids, alkalis, oils, and UV light, making it ideal for outdoor applications like garden tools, automotive components, or UV-exposed signage."

No PETG maker here publishes weathering test results. Polymaker's product-page caveat is the most cautious statement, so plan around it for parts that will sit in strong sun for years.

Heat. Polymaker's pages also disagree on PETG's heat limit. The wiki says PETG withstands "up to 80°C," while the product page gives "approximately 70 °C HDT." The product page's spec table gives 65 °C at 1.8 MPa and 69 °C at 0.45 MPa (ISO 75). Prusa's 80 °C guide figure and the Prusament page's 68 °C differ the same way. Our heat deformation guide has the full tables. Bambu Lab's PETG HF data sheet (V1.0) gives 62 °C at 1.8 MPa and 69 °C at 0.45 MPa (ISO 75), from specimens "annealed and dried at 75 °C for 8 h." Those figures are below its PETG Basic sheet's 68 °C and 71 °C. eSUN's PETG page lists a heat distortion temperature of 64 °C without a test load.

Is ABS UV resistant?

ABS is where makers disagree most.

• Prusa's ABS guide lists "Lacks UV resistance (unlike ASA)" as a drawback. Its introduction is softer, saying that compared with ASA "there is slightly worse UV resistance," but adds that "ABS parts used outdoor turn yellowish and more brittle over time."
• Polymaker's ASA wiki page compares the two in a table, rating UV resistance "Excellent" for ASA and "Poor" for ABS, and outdoor use "Ideal" for ASA and "Not Recommended" for ABS. It says ASA, "Unlike ABS," "retains its color and mechanical properties even after prolonged sun exposure."
• Bambu Lab's ABS data sheet (V3.0) opens by describing ABS as "known for its superior comprehensive properties such as high temperature resistance, UV resistance and water resistance." Its ABS store page doesn't mention UV. It claims "Good Heat & Freezing Resistance" and says Bambu ABS "ensures relatively long-lasting durability when used in a wet environment." Bambu Lab's own ASA page draws a line between them: ASA provides "better resistance to fading, yellowing, and degradation from sunlight exposure," while ABS "is commonly used for indoor applications."
• eSUN lists "Outdoor Decoration" among the applications for its ABS+ but makes no UV claim for it. Its page also gives two heat figures. The feature text says "Heat deflection up to 89'C," mentioning "in-car heat exposure," but the spec table lists a heat distortion temperature of 73 °C. Neither states a test load, so plan around the lower figure.

So two makers say ABS is a poor outdoor choice, one data sheet says it resists UV, and Bambu Lab's ASA page still points outdoor parts to ASA. If the part will see years of sun, the published evidence points to ASA. See ABS vs ASA for the trade-offs at the printer.

ASA: the outdoor material, with one caveat

Every ASA maker we checked sells it for outdoor use. Our ASA vs PETG guide covers the printing side. Here's what each maker says about sunlight and colour:

• Prusa: the ASA guide calls it "a technical material suitable for outdoor use, due to its high UV light and temperature resistance." The Prusament ASA page says that "Thanks to UV stability," the material "will keep toughness and durability for a long time and will not turn yellow."
• Polymaker: the FAQ on its ASA product page reports test results. After "a two-year natural aging examination," it reports a "slight color alteration" with a colour change (ΔE) "below 2.5." In accelerated aging, it reports a ΔE "below 5 and minimal tensile strength loss, even after exposure to 8000 kj/m2 irradiation, showcasing superior performance compared to ABS." It concludes that parts exposed to "sunlight, rain, temperature fluctuations" "maintain integrity for a minimum of two years." It's the only lifespan figure we found from any maker, and it describes Polymaker's own ASA.
• Bambu Lab: its ASA page says the material "offers extraordinary UV, oxidation, and aging resistance, providing effective protection against breakage and color degradation when used outdoors for long-term purposes." The ASA data sheet suggests "plant signs, mailboxes, wind vanes" and parts "that require long-term exposure to challenging outdoor conditions."
• eSUN: says that under long-term sunlight ASA+ "effectively resists UV radiation," "preventing fading, yellowing, or brittleness of prints," and that "the color of the printed product is consistent."
• SUNLU: the product page says its ASA remains "fade-resistant and shape-stable even after prolonged exposure to outdoor conditions." Its data sheet adds a caveat in the handling section: "The product may yellow under the action of ultraviolet light, so it should be stored away from direct sunlight." The two documents don't say whether that applies to the spool, the printed part, or both.
• OVERTURE: says its ASA is "specially formulated for maximum UV protection," offered in "fade-resistant colors," with "superior UV resistance and greater stability in outdoor environments compared to ABS."
• Anycubic: the product page says its "anti-UV and anti-oxidation formula" lets the ASA keep "both structural integrity and vibrant color" in "intense sunlight" and "heavy rain and high winds." Its data sheet describes "rain and UV resistance, making it suitable for outdoor environments."
• ERYONE: claims "Superior heat, chemical, and weather resistance for outdoor applications" for its high-speed ASA.

Only Polymaker backs its claim with numbers. SUNLU is the one maker whose own documents both promise fade resistance and warn of yellowing. To see two of these ASA spools side by side, read Polymaker ASA vs Overture ASA or eSUN ASA+ vs SUNLU ASA.

Heat. In Bambu Lab's data sheets and on Polymaker's and Prusament's pages, each maker's ASA has a higher heat rating than its PETG. The heat deformation guide has Bambu Lab's, Polymaker's and Prusament's figures. The other ASA makers publish in different formats:

PC: makers contradict each other

• Polymaker's PC wiki page lists "UV Sensitivity: Degrades under prolonged sunlight unless coated" as a limitation of PC.
• eSUN says its PC-HT adds chemical resistance to "the excellent weather resistance inherent to PC," which it says helps parts keep "their appearance and structural integrity, even in outdoor and other demanding environments."
• Prusa lists "Good UV stability and resistance to common chemicals" for Prusament PC Blend Carbon Fiber specifically. That page says that "Unlike the unmodified PC Blend," the carbon-fiber grade has "good resistance to UV light and common chemicals."

The disagreement is between a general wiki statement about PC and two product-specific claims. If you need PC's heat resistance outdoors, pick a grade whose maker makes an outdoor claim for that product. Our polycarbonate guide covers PC's heat figures and printing needs.

TPU: few outdoor claims

Makers say little about TPU in sunlight:

• Polymaker's TPU wiki page says TPU "Withstands industrial solvents and UV exposure, suitable for outdoor use." It's a general statement about TPU, not a product test.
• Prusa's flexible materials guide says flexible filaments "stay flexible even in cold environments," and makes no UV claim. The Prusament TPU 95A page lists "High resistance to hydrolysis and microbial degradation" and says its elasticity and impact resistance "remain even at low temperatures (as low as -50 °C)." It lists a heat resistance of 78.6 °C "Under 1.80 MPa."
• Bambu Lab's TPU 95A HF page makes no outdoor or UV claim, and its data sheet lists HDT as "N / A."

If a flexible part has to live in the sun, ask the maker of your exact TPU about UV before relying on it. Our TPU hardness guide covers choosing a grade.

Carbon-fiber grades

Most carbon-fiber grades make the same outdoor claims as their base material:

• Bambu ASA-CF: the product page calls it "one of the top materials for outdoor use, with excellent resistance to harsh weather and UV exposure," and its data sheet (V1.0) says it is "Engineered for harsh outdoor conditions." HDT is 102 °C at 1.8 MPa and 110 °C at 0.45 MPa (ISO 75), against 92 °C and 100 °C for Bambu ASA. Both sheets say their specimens were annealed and dried at 80 °C for 12 hours.
• Bambu PETG-CF: the product page says "Thanks to its enhanced resistance to heat and moisture, Bambu PETG-CF is ideal for outdoor applications." Its data sheet (V3.0) gives 68 °C at 1.8 MPa and 74 °C at 0.45 MPa (ISO 75), from specimens annealed at 65 °C for 8 hours. That matches PETG Basic's 68 °C at 1.8 MPa and is 3 °C higher at 0.45 MPa.
• Prusament PETG Carbon Fiber: Prusa says it gives "very durable, professional-looking prints suitable even for outdoor use."
• Prusament PC Blend Carbon Fiber: "Good UV stability," as above.
• Polymaker's wiki describes PETG-CF as balancing "rigidity with UV/chemical resistance," with "outdoor fixtures" as an application. It calls PLA-CF "Brittle; unsuitable for high-stress or high-temperature environments."

Prusament PC Blend Carbon Fiber is the one grade here whose maker claims better UV resistance than the unfilled base, and Prusa doesn't say whether the fiber is the reason. Check the claim for the exact grade. Fiber grades also need a hardened nozzle. See our carbon fiber filament guide.

Water, rain and moisture

Two different things get called "water resistance":

The finished part. Makers that address rain mostly mean the part holds up when wet. Prusa calls PETG "Water and humidity resistant" and Prusament says PETG prints suit "waterproof applications" because of layer adhesion. Bambu Lab says its ABS ensures "relatively long-lasting durability when used in a wet environment." eSUN, SUNLU and Anycubic mention rain for their PETG or ASA. Prusament TPU 95A's "High resistance to hydrolysis" is the most specific water claim for a flexible material.

The material soaking up water. Bambu Lab's data sheets give a saturated water absorption rate at 25 °C and 55% RH for each material:

Bambu Lab doesn't link these figures to how long a part lasts outdoors. They describe test specimens, and other makers test under other conditions. Prusa calls ASA "Partially hygroscopic (absorbs moisture)."

The spool before printing. This matters more for print quality. Bambu Lab's filament pages say to store filament "in a cool, dark, and dry environment away from direct sunlight and high temperatures," and SUNLU's ASA data sheet says to store it "away from direct sunlight." Don't leave a spool in a sunny shed. Our filament storage guide and wet filament guide cover drying and storage.

Heat in the sun

Sun brings heat as well as UV, and the heat limit is often what fails first. Our heat deformation guide compares each maker's HDT figures at the same load and covers annealing. Some extra points from this research:

• Compare HDT only at the same load (1.8 MPa or 0.45 MPa) and preferably from the same maker. Several product pages give a single figure with no load: Bambu ABS (87 °C, which matches its data sheet's 0.45 MPa figure), eSUN ABS+, eSUN PETG and eSUN ASA+.
• Bambu Lab's ASA page has a comparison table headed "Heat Resistant (HDT, 0.45 MPa)" that lists PC at 117 ℃. Bambu Lab's PC data sheet (V2.0) gives 117 °C at 1.8 MPa and 112 °C at 0.45 MPa. The two documents don't agree on which load the 117 °C belongs to.
• Polymaker's wiki says "Thin-walled or low-density prints are more prone to warping and deformation when exposed to heat," and that a print's heat resistance "cannot be determined by material rating alone." A thin part can sag in the sun even when its material has a good rating.

Side-by-side summary

All entries are manufacturer statements about specific products or materials. Other brands and grades differ.

Choosing for an outdoor part

• Years in direct sun, or colour matters: ASA, from a maker that publishes its outdoor claims, ideally with test data. Check the maker's enclosure and ventilation guidance. See ASA vs PETG.
• Partial sun, rain or damp, on an open-frame printer: PETG. Its makers call it suitable outdoors, but Polymaker's caveat about prolonged exposure applies.
• Outdoor PLA: only a grade whose maker makes an outdoor claim for it, such as Polymaker Matte PLA for Production, and only where the part stays cool enough for PLA.
• Stiff outdoor parts: an ASA-CF or PETG-CF grade sold for outdoor use, with a hardened nozzle.
• Hot as well as sunny: check the HDT at the same load in the heat deformation guide, then the UV claim for that exact product.
• Flexible outdoor parts: confirm with the TPU maker. Most don't make a UV claim.

Checklist before you buy

• Write down how much direct sun the part gets, the highest temperature it may reach, and whether it gets wet.
• Find the outdoor or UV statement for the exact product, not the material in general.
• Check whether the maker publishes weathering test results or just a description.
• Compare heat figures at the same test load, from the same maker where possible.
• Look for caveats in the data sheet's handling or storage section, like SUNLU's yellowing note.
• Check that your printer can handle the material: enclosure, nozzle and bed temperatures, and a hardened nozzle for fiber grades.
• Store the spool dry and out of direct sunlight.
• Plan to inspect outdoor parts over time. Makers' lifespan claims cover their own tests, not your climate.

Ready to choose?

The ASA filament shortlist matches verified ASA spools to the printers they suit, with each maker's UV, enclosure, heat and drying guidance. The PETG filament shortlist covers PETG for open-frame printers and moderate outdoor use. For stiffer outdoor parts, see the carbon fiber filament shortlist. To compare the two main outdoor materials in depth, read ASA vs PETG and ABS vs ASA.

How this guide was checked

This is a research-based guide. We haven't weathered any prints for it. Every claim comes from the manufacturer documents listed in the sources, retrieved on 2026-10-13, and is attributed to the maker and product it came from. We used visible page text and data sheets only, not customer reviews. Product-page FAQs were used only where the maker answers them. Where a maker's documents disagree with each other or with another maker, we've said so. Read more in our editorial standards and affiliate disclosure.

Specialty materials: what to check before you buy a spool ↗