One of the most common questions in the 3D printing community is: “How long will my printed masterpiece last?” The internet is flooded with conflicting information – from one year to forever – depending on the type of plastic, the manufacturer, and the writer’s bias. One of the most questioned materials is “biodegradable” PLA, which some claim has a short lifespan by design. In contrast, others argue that plastics like PETG could outlast humanity itself. While the “green” community praises some materials and criticizes others, we decided to conduct an independent experiment under real-world conditions to get some answers.

Experiment Objective and Conditions: Several printed objects made from the most common types of thermoplastics will be stored in an open, mesh container outdoors for several years. They will be exposed to intense sunlight, both hot and cold winds, rain, and snow. Essentially, they will endure all the challenges posed by a sharply continental climate, with temperature fluctuations ranging from +40°C in the summer to -40°C in the winter.

The objects include parts, figurines, toys, and small test samples made from the following types of plastic:

• PLA (4 types)
• SBS
• HIPS
• PETG (2 types)
• NYLON
• FLEX
• TPU

The samples were placed outdoors on April 13, 2019. As of the writing of this article, nearly three years have passed, and we now have some surprising results to share.

Year One

After surviving the first scorching summer, the first cold winter, and damp transitional seasons, the samples were brought inside, cleaned of accumulated dust, and carefully inspected.

PLA, the material with the least expected durability, was the first to be examined. One large, thin-walled part showed slight deformation, probably due to excessive heat from the sun, but to our surprise, no other “aging” changes were observed. All PLA items looked as if they had just been printed, and their physical properties remained intact. The structure and strength were as good as new. We must admit, PLA pleasantly surprised us.

PETG showed no changes at all and maintained its signature glossy finish. As expected, the durability of this material was unquestioned.

HIPS (on the right) also showed no visible changes. SBS (on the left) became slightly darker and lost some transparency, which seemed odd since the manufacturer claims it is “weatherproof” and should not change structure over time.

FLEX also performed well, showing no loss in appearance, strength, or flexibility after the first year.

NYLON absorbed water and turned from clear to milky white. However, this had no impact on its mechanical properties – the legendary strength of nylon remained intact, and the wide “skirt” could still not be torn by hand.

Summary: After one year outdoors, all plastics showed little to no change. The strength and appearance of all samples were maintained, except for one PLA sample, which experienced slight geometric changes. However, it was already known that PLA “melts” when exposed to direct sunlight, so its thermal resistance was not expected to be high.

The samples were returned to their original position and left outside for another year.

Year Two

It’s now April 25, 2021, and our test subjects have been exposed to the elements for over two years. We bring them back inside, clean them, and check their condition.

PLA. No changes yet – visually or to the touch. All the samples are exactly as they were two years ago, even the lid that slightly bent in the first year shows no new changes. PLA continues to amaze us, as many reviewers had predicted it would last only one or two years under outdoor conditions, but it hasn’t even yellowed. Standing ovation.

PETG also performed flawlessly, showing no changes compared to new prints. It remains strong, beautiful, and pleasant in every way.

HIPS seems to have lightened slightly, but otherwise, it remains in excellent condition, indistinguishable from prints made yesterday.

NYLON is as strong as ever, and even looks more transparent than it did a year ago. Its color may depend on environmental humidity, which fluctuates over time. The “skirt” is still intact and nearly impossible to tear by hand.

SBS has significantly deteriorated, becoming darker and more opaque. When tested for strength, it crumbled at the slightest pressure, breaking apart like sugar cubes without resistance. This was our first failure, and the sample was removed from the experiment, losing its “weatherproof” designation. Likely, UV exposure caused this degradation, so it is no longer recommended for outdoor use.