3D printing and the environment: what is true and what is marketing

PLA is sold as biodegradable and plant-based, and both are true with small print almost nobody reads. Here it is, because choosing a material well also means knowing what happens to the part at the end of its life.

Biodegradable PLA, in full

PLA degrades in an industrial composting plant: sustained temperature above 55 °C, controlled humidity and the right microorganisms. In the composter on your terrace, in landfill or in the sea, a PLA part behaves much like any other plastic for a very long time. Putting it in the organic bin and expecting it to disappear will not work. And that is its behaviour out of the sun; outdoors it turns brittle and fragments, which is worse still.

Where the impact actually is

• The support that gets thrown away. A badly oriented part can generate as much support material as part. Designing and orienting to avoid it is the most effective environmental measure in the process, and it is cheaper too.
• Failed prints. A part that lifts off the bed at six hours is wasted material and electricity. That is why a small test before the big part is not only economic prudence.
• Unnecessary infill. Printing at 60% what would work at 20% triples the plastic in an interior nobody will see or use.
• Electricity. Real but modest: a printer draws on the order of a small appliance, not an industrial oven. Total time counts more than power.

What to do with a printed part that is finished

The plastics bin is the reasonable destination in practice, though it is worth knowing that PLA is not one of the plastics sorting plants separate well, so it will probably end up in the reject stream. Filament recycling schemes exist and work, but they need clean material, separated by type, free of paint and glue. If you have volume — a workshop accumulating supports and failures — it is worth finding a point that collects PLA specifically rather than mixing it in.