Glossary · Material

3D printing

Filament

The printing material for most 3D printers: a thin plastic wire wound on a spool.

Explained in more detail

A thermoplastic strand of standardised diameter, today almost always 1.75 mm (more rarely 2.85 mm). Important quality features are diameter tolerance (good manufacturers about ±0.02 mm), roundness and dryness. Many filaments are hygroscopic, meaning they absorb moisture from the air. This leads to bubbles, strings and rough surfaces. Besides pure plastics there are filled variants with carbon or glass fibres, wood or metal particles.

Where does the term come from?

From Latin filum, "thread". In English, filament generally means a thin thread, for example also the filament of a light bulb. In 3D printing it refers to the plastic strand on the spool.

In practice

• You will find the diameter on the label: most current printers need 1.75 mm, and 2.85 mm only fits devices designed for it.
• Crackling during printing, more strings and rough surfaces point to damp filament; drying almost always fixes it.
• Store opened spools in an airtight box with desiccant; under 20% relative humidity is a good guideline.
• Filament with carbon or glass fibres, glitter or glow pigments wears down brass nozzles and needs a hardened nozzle.
• A standard spool holds 1 kg of filament. If you know the empty weight of the spool, you can easily determine the remaining amount with a kitchen scale.

Not to be confused

Filament is the material, not the process. Anyone who speaks of a filament printer means an FDM printer.

Frequently asked questions

Which filament is best for beginners?

Usually PLA: it prints at 190 to 220 °C, needs only 50 to 60 °C bed temperature and hardly warps. For more heat-resistant or tougher parts, PETG is the next step.

Can filament go bad?

The biggest problem is moisture, not age. Damp filament prints with bubbles, stringing and a rough surface, but in most cases it can be used again after drying.