The most common problem we see with parts printed elsewhere is not a design fault. It is a material chosen indoors for a job that happens outdoors.
PLA is the default on almost every desktop printer, for good reasons. It prints easily, holds dimensions well and has the cleanest surface finish of anything we run. It is also the wrong answer for a Maltese summer, and the failure is not subtle.
What actually happens to PLA in the sun?
Two separate processes, and they compound.
It softens. PLA has a glass transition temperature around 60°C — the point at which it stops behaving like a rigid solid and starts behaving like something you could dent with a thumbnail. That sounds high until you measure real surfaces. A dark object on a windowsill or a dashboard in July passes it comfortably. Parts do not melt dramatically; they sag, warp and lose their fit over days.
It degrades. Ultraviolet light breaks the polymer chains. The part becomes brittle rather than soft, and eventually snaps under a load it carried fine last season. Colour goes first, usually to a chalky version of itself.
Add the coastal air most of this island has, and a PLA part in permanent outdoor use is on a clock. Not a long one.
Is PETG good enough for outdoors?
Sometimes, and this is where people get caught out.
PETG stays stable to around 80°C and resists moisture well, so it survives things PLA does not — splash zones, sheltered exteriors, a shaded balcony. For a season or two of indirect exposure it is genuinely fine, and it costs less than the alternative.
What PETG does not do well is *sustained direct* UV. Over a couple of Maltese summers in full sun it yellows and slowly loses toughness. If the part is sheltered, PETG is the sensible economic choice. If it is in the sun all day, every day, it is a false economy.
What should you actually use outdoors?
ASA. It was developed for exactly this.
ASA is UV-stable and colour-fast, and stays rigid to around 100°C. It does not yellow, and it does not become brittle after a season the way PLA does and PETG eventually will. 3DOME Malta prints anything permanently exposed in ASA — outdoor mounts, signage, garden and terrace pieces, and statues destined for a conservatory or a sunny windowsill.
It costs a little more per part and is slightly fussier to print. On anything that has to last, that is not a close decision.
So is PLA ever the right choice?
Very often — indoors.
PLA gives the sharpest surface detail of any filament we run, which is why it is the standard choice for 3D printed busts and display pieces where the finish is the whole point. It is also the best option for visual prototypes, indoor keepsakes and gifts that will live on a desk or a shelf.
The mistake is not using PLA. The mistake is using PLA by default without asking where the part is going to live.
How do you choose in practice?
At 3DOME Malta the question we ask before quoting is not "what material do you want" but "where will this live and what does it have to survive". The answers map fairly cleanly:
- Indoors, detail matters — PLA
- Handled daily, carried, sheltered outdoors — PETG
- Permanent sun, full outdoor exposure — ASA
- Heat and mechanical stress, indoors — ABS
- Needs to flex — TPU
The full comparison, with heat tolerance, tensile strength and UV stability side by side, is on our materials page.
What if a part has already failed?
Bring it, or photograph it. A part that warped or snapped tells us more than a description does — where it failed usually says whether the problem was material choice, wall thickness or print orientation.
Reprinting the same design in a better material fixes the first. Fixing the other two means changing the design, and if the original failed because of a design weakness we would rather reinforce it than faithfully reproduce the flaw.