Choose a material for outdoor and UV-exposed parts

Outdoor parts face three things at once: ultraviolet light, heat from the sun, and moisture. In a tropical climate like Malaysia’s, all three are strong all year. A part that is perfectly fine indoors can fade, chalk and crack within a season outside.

What fails outdoors

• UV degradation. UV light breaks polymer chains at the surface. You see fading and a chalky finish first. Later the surface turns brittle and cracks start there.
• Heat. A dark part in direct sun can get far hotter than the air around it. Materials that soften at modest temperatures will sag.
• Moisture. Water uptake changes the size and stiffness of some materials, nylon in particular. Repeated wetting and drying adds stress.
• Thermal cycling. Daily hot and cool cycles open up weak layer lines over time.

Which properties matter

Datasheets rarely give a single “UV resistance” number, so read the description and our outdoor badge first. Then check heat deflection temperature to make sure the part will not soften in the sun, and impact strength because weathered surfaces lose toughness first.

Material families that usually work

• ASA is the usual first choice for printed outdoor parts. It behaves much like ABS but is designed to resist UV. Our ASA grades show an HDT of 87–100 °C (median 97 °C, 9 materials).
• UV-stabilised PETG and PC blends can work well, but only when the grade says it is stabilised. Plain PETG yellows and embrittles over time.
• PP and PVDF resist weather and chemicals well. Some PP grades need UV stabiliser to last.
• Fibre-filled nylons can be strong outdoors, but plan for moisture uptake.
• Standard resins and PLA are poor choices for long outdoor life. Most photopolymers keep reacting to UV and turn brittle.

1. Photopolymer 944–90
2. PETG 664–85
3. ASA 987–100
4. PP 573–135

Bar = lowest to highest, dot = median. 29 materials, live from our database.

Process considerations

FFF gives you access to ASA and stabilised blends, which is why it dominates printed outdoor parts. Resin parts need a UV-blocking coating to survive outside, even if the resin itself is tough. Powder nylon parts are tough and sealed when dyed and coated, but plain nylon still absorbs water.

Design and post-processing tips

• Pick lighter colours to keep surface temperatures down, or black when the grade relies on carbon black for UV protection.
• Coat it. A UV-resistant clear coat or paint protects any material and is essential for resin parts.
• Use thicker walls and more perimeters. The outer skin weathers first, so give the part some to spare.
• Use stainless fasteners and avoid trapping water in pockets.
• Allow for expansion. Long parts grow and shrink with temperature, so do not over-constrain them.

A shortlist from our data

We flag 50 materials as suited to outdoor or UV-exposed use. Of the filaments, these hold up best to heat:

Check the test load on each HDT value. Our article on HDT test loads explains why it matters.

Common mistakes

• Assuming any PETG or ABS is UV-stable. Only stabilised grades are.
• Testing indoors for a week and calling it validated. Run a real outdoor trial, or accelerated weathering, before committing.
• Forgetting sun-heated surface temperature when checking HDT.
• Leaving resin parts uncoated.

See all outdoor and UV-resistant materials 50 materials