Filament Materials

Choosing a filament

A filament choice is a compromise between four things: how easily it prints, how strong and stiff the part is, how hot it can get, and what it must resist (sunlight, water, oils, impact). Printed plastic is a thermoplastic: it softens and flows when hot, and for an amorphous plastic such as PLA, PETG, ABS or polycarbonate that starts near the glass transition temperature T_g, long before the plastic melts. That temperature, not the melting point, is the limit of what a part can do in service.

If you need…	Try	Because
The easiest print, a prototype or model	PLA	Low temperature, little warping, fine detail
A tough part with some heat and chemical resistance	PETG	Tougher and less brittle than PLA; softens near 80 °C
Outdoor, sun and heat resistance	ASA (or PETG)	ASA keeps its strength in UV; needs an enclosure
Higher heat resistance, post-processing	ABS	Sands, glues and smooths with acetone; warps and emits styrene
A wear-resistant, tough part such as a gear or hinge	Nylon (PA12 or PA6), or carbon-filled nylon	Low friction and fatigue-resistant; absorbs water
A stiff, light part	PLA-CF or PA-CF (carbon filled)	Stiffer and less warp; abrasive: needs a hardened nozzle
A flexible part: seals, grips, bumpers	TPU (95A)	Elastic; print slowly
High strength and heat resistance	Polycarbonate or PC blends	Needs a 260 to 310 °C hotend and an enclosure

The common materials compared

Material	Nozzle / bed (typical °C)	Tg or softening (approx.)	Tensile strength, printed (MPa, typical)	Stiffness (GPa, typical)	Notes
PLA	190–220 / 20–60	60 °C	45–60	3 to 3.5	Brittle; creeps under steady load; biodegrades only in industrial composting
PETG	220–250 / 70–85	80 °C	40–50	1.8 to 2.2	Tough; strings; absorbs some water; good chemical resistance
ABS	230–260 / 90–110	100–105 °C	30–45	1.8 to 2.3	Warps; styrene fumes; dissolves in acetone
ASA	235–260 / 90–110	100 °C	30–45	1.8 to 2.2	Like ABS, but UV resistant
Nylon (PA6, PA12)	240–270 / 70–90	Tg 40–60 °C dry; use to 80–120 °C	40–70	1 to 2 (more when filled)	Absorbs water; dry before use; warps
Polycarbonate	260–310 / 100–120	110–147 °C	50–65	2 to 2.4	Strong and heat-resistant; hard to print; absorbs water
TPU 95A	210–230 / 30–60	n/a (elastomer)	30–40 (elongation 400 % +)	0.02 to 0.05	Flexible; slow feed; direct drive preferred
PLA-CF / PA-CF	As the base plastic	As the base plastic	50–90	5 to 10	Stiff; abrasive; weaker layers across Z

Datasheet properties are measured on molded or well-printed specimens in the strongest direction, and a real printed part is lower and directional (see Strength, Accuracy and Fits). Treat these as typical values to compare materials, and check the maker’s datasheet for the filament you use. For comparison with other materials see Material Properties.

Printing temperatures

• Temperatures are starting points. Use the maker’s range on the spool, then tune with a temperature tower (a model that changes temperature as it rises): choose the temperature that gives the best surface, bridging and layer bonding without stringing.
• Higher temperature improves layer bonding and flow but increases stringing and oozing and can burn the plastic; lower temperature gives sharper detail and less stringing, with weaker layers.
• Bed temperature is set near (and a little under) the glass transition so that the base stays sticky but not molten: 50–60 °C for PLA, 70–85 °C for PETG, 90–110 °C for ABS and ASA.
• Enclosure temperature matters for ABS, ASA, nylon and PC: a warm chamber (35 to 60 °C) reduces warping and cracking.

PLA and its variants

PLA (polylactic acid) is the default filament: it prints at low temperature, barely warps and gives crisp detail. It is stiff and strong for its weight but brittle, and it creeps (slowly deforms) under steady load, and softens at about 60 °C, which a closed car in sunlight reaches (the dashboard of a parked car can exceed 70 °C). Variants: PLA+ and tough PLA (impact modifiers, less brittle), silk and matte PLA (finish), wood and metal-filled PLA (abrasive), glow-in-the-dark (very abrasive), and high-temperature PLA (annealable grades). Annealing PLA in an oven can raise its heat resistance to 90 to 110 °C, but the part shrinks and distorts (see Post-processing and Finishing).

PETG

PETG (glycol-modified polyethylene terephthalate) is tougher and more flexible than PLA, handles water and many chemicals, and is a good general engineering choice. It sticks hard to smooth PEI (use a release agent), strings readily, and scratches. It needs less cooling than PLA (30 to 60 percent fan) and a slower print speed for the best layer bond. It absorbs some moisture: dry it at about 60 to 65 °C for 4 to 6 hours if it pops or strings.

ABS and ASA

ABS and ASA (acrylonitrile styrene acrylate) are heat-resistant, machinable and, for ABS, can be smoothed with acetone vapor. Both shrink about 0.5 to 0.7 percent on cooling, which makes them warp and crack without an enclosure, a heated bed and low fan. ASA resists sunlight and weathering where ABS yellows and weakens. They emit styrene and other vapors: print in a ventilated enclosure, not in a living space (see Troubleshooting and Safety).

Nylon and polycarbonate

Nylon (polyamide, PA6, PA12, PA66) is the engineering favourite: tough, low friction and fatigue-resistant, good for gears, bushings, hinges and living hinges. It absorbs moisture from the air (several percent by weight), which lowers its stiffness, causes steam bubbles and rough surfaces when printed wet, and changes dimensions: always dry nylon (70 to 80 °C for 8 hours or more) and print from a dry box. It warps; use a garolite or PEI bed with glue, an enclosure, and a brim. Polycarbonate is strong and heat resistant but needs 260 to 310 °C, a high bed temperature and an enclosure; PC blends (PC-ABS, PC-PBT) are easier.

TPU and flexible filaments

TPU (thermoplastic polyurethane) is an elastomer measured on the Shore hardness scale: 95A is a firm rubber, 85A and 75A are softer. It prints best on a direct-drive extruder at low speed (15 to 30 mm/s) with little retraction, because the soft filament buckles in a Bowden tube. Parts take large strains and recover, which makes them good for seals, gaskets, bumpers, grips and wheels. Infill lets you tune the stiffness: lower density gives softer parts.

Filled and composite filaments

Filler	Effect	Watch out for
Carbon fiber	Stiffer, lighter, less warping, matte finish	Very abrasive (hardened nozzle); brittle across layers; electrically conductive
Glass fiber	Stiffer and more heat resistant	Abrasive; rough surface
Metal powder (bronze, steel)	Heavy, metallic look, can be polished	Abrasive; brittle; costly
Wood, stone, glow-in-the-dark	Appearance	Abrasive or clog-prone; weaker parts
Conductive, ESD-safe	Static dissipation or conductive tracks	Resistance varies widely; check the datasheet

Moisture, drying and storage

Many filaments absorb water from the air: nylon, PVA, TPU, PETG, PC and PLA to a lesser degree. Wet filament pops and hisses, strings, leaves a rough surface and makes weak parts. Drying removes the water, and a sealed box with desiccant keeps it out.

Material	Drying (typical)	Notes
PLA	45–55 °C, 4–6 h	Do not exceed the softening temperature
PETG	60–65 °C, 4–6 h
ABS / ASA	70–80 °C, 4 h
Nylon	70–80 °C, 8–12 h	Print straight from the dryer
TPU	45–55 °C, 6–8 h
PC	80–100 °C, 6–8 h	Very moisture sensitive

• Store sealed with desiccant (silica gel) and a humidity indicator; keep the printing spool in a dry box for nylon, PETG and TPU.
• Filament dryers are inexpensive; a food dehydrator or a small oven also works if its thermostat is accurate (check with a thermometer).
• Humidity limits: keep relative humidity below about 20 % for nylon, 30 to 40 % for PETG and PLA.

Spool length, mass and cost

The length of filament on a 1 kg spool follows from its density and the cross-section of the 1.75 mm filament (2.41 mm²). A denser plastic gives a shorter spool.

Material	Density	Mass per meter (1.75 mm)	Length per kg
PLA	1.24 g/cm³	2.98 g	335 m
PETG	1.27 g/cm³	3.05 g	327 m
ABS	1.04 g/cm³	2.50 g	400 m
ASA	1.07 g/cm³	2.57 g	389 m
Nylon (PA12)	1.02 g/cm³	2.45 g	408 m
TPU 95A	1.21 g/cm³	2.91 g	344 m
Polycarbonate	1.20 g/cm³	2.89 g	346 m
PLA-CF (carbon)	1.30 g/cm³	3.13 g	320 m

Related

• 3D Printing and Additive Manufacturing: the overview of this guide.
• Slicer Settings and Print Quality: temperature, cooling and flow settings.
• Strength, Accuracy and Fits: what printing does to material strength.
• Material Properties: strength, stiffness and thermal data.
• Troubleshooting and Safety: fumes, fire and failures by material.

FAQ

Which filament should I start with?

PLA. It prints at low temperature, barely warps, needs no enclosure and gives good surface quality. Move to PETG for tougher or outdoor parts, and to ABS, ASA or nylon when you need heat resistance or toughness and have an enclosed printer.

Is PETG stronger than PLA?

PETG is tougher (it bends and absorbs impact instead of snapping) and tolerates more heat, though PLA is often stiffer and slightly stronger in tension. For a snap-fit, hinge or part that must not shatter, choose PETG.

Do I need a hardened nozzle?

Only for abrasive filaments: carbon or glass fiber, metal and wood fills, glow-in-the-dark. Plain PLA, PETG, ABS and nylon print fine in brass.

Is 3D-printed plastic food safe?

Generally not. Layer lines trap bacteria, the nozzle may contain lead, and additives vary. Use food-contact parts only where the filament maker states it is food safe, and even then expect the surface to harbor germs.

References

• Filament makers’ technical data sheets (for example Prusa, Polymaker, Bambu Lab, eSun) for temperatures and properties.
• Stratasys and Ultimaker material data sheets for ABS, ASA, nylon and PC properties.
• Gibson, I., Rosen, D. and Stucker, B., Additive Manufacturing Technologies, Springer (material families).

Last reviewed: October 2026. Properties vary by brand and by how a part is printed: treat the figures as typical.