PA6 vs PA12: comparing nylon filament families

Two polyamides, one shared weakness at different levels

PA6 and PA12 both belong to the polyamide family, which the Prusa knowledge base describes as highly abrasion resistant, with excellent layer adhesion, a high melting temperature and a low coefficient of friction. Prusa also calls nylon very hard to print and recommends it for experienced users only. That general overview does not certify the properties of every PA6 or PA12 grade.

The difference that matters is water. According to Prusa, polyamide is hygroscopic and must be kept airtight with desiccant, since improper storage can let it absorb up to 10% of its weight. That warning covers nylon broadly, without separating PA6 from PA12. Polymaker's PA12-CF sheet, by contrast, puts the low moisture sensitivity of PA12 front and center as the main reason to choose that grade.

The general nylon material page covers the whole family. The angle here is narrower: what the sheets say about moisture uptake and about properties before and after water exposure, and above all under what conditions those numbers were produced. Wet filament makes bubbles, and Prusa links that directly to uneven layers and a rough surface.

What the sheets say about moisture uptake

The Fiberon PA12-CF 10 sheet publishes an absorption curve labeled 23 °C and 70 % relative humidity, with a stated equilibrium water absorption of 1.5 %. That air-exposure condition differs from the immersions used for the mechanical tests below. The sheet does not present it as a simulation of a workshop part and supplies no mechanical properties after that particular conditioning.

The same sheet states that the wet specimens used for mechanical testing were immersed in 60 °C water for 48 hours, reaching an average moisture content of 2.92%. That protocol describes the wet conditioning used for this sheet's mechanical tests; it is not the same condition as air equilibrium at 23 °C and 70% RH, and the sheet does not present it as a worst case in service. Polymaker's PA12-CF document uses yet another protocol: 3 days immersed in room-temperature water, with no moisture content reported.

On the PA6 side, none of the supplied sources publishes a curve or an uptake percentage. The Polymaker document states that, compared with PolyMide PA6-CF and other PA6 products on the market, the absorption of its PA12-CF is the lowest. That is a manufacturer statement about its own products, not an independent measurement. The practical rule is the same for both families: store dry, as covered in the guide to filament dryers.

Dry versus wet properties: read the test conditions first

The Fiberon PA12-CF10 sheet publishes dry and wet values under the same standards, ISO 527 for tensile, ISO 178 for flexural and ISO 179 for Charpy impact, on specimens annealed at 100 °C for 16 hours. In the XY plane it lists 77.4 MPa tensile strength dry versus 71.7 MPa wet. Along Z, tensile strength drops from 52.2 to 42.1 MPa. XY bending strength goes from 112.4 to 91.8 MPa. XY Young's modulus slips from 3311 to 3132 MPa.

Un-notched XY Charpy impact moves the other way, from 33.7 to 41.2 kJ/m², while the modulus drops; the sheet publishes these figures without explaining the cause. These values can be compared with each other because the protocol is identical across both columns. Polymaker's PA12-CF document presents a dry versus wet chart for PA6-CF and PA12-CF, with a note that one asterisked value was recorded at the maximum displacement of the testing machine because the specimen neither broke nor yielded.

What you cannot do is compare Fiberon's numbers to Polymaker's. The wetting protocols differ, 48 hours at 60 °C on one side and 3 days at room temperature on the other. Fiberon publishes a 100 °C, 16 hour anneal for its specimens, while Polymaker's comparison chart does not specify that parameter, so the protocols are not fully comparable. The Fiberon sheet also states that its typical values are for reference and comparison only, not design specification, and the PolyMide document describes itself as basic guidelines. Carbon grades are covered in more depth on the carbon fiber nylon page.

Temperatures, bed and enclosure: two different print profiles

The Prusa knowledge base, which addresses polyamide in general, recommends a 285 °C nozzle, a 110 °C bed and its dedicated PA Nylon sheet for adhesion. It adds that pure nylon is prone to warping and that a high ambient temperature, meaning an enclosure, helps a lot. Prusa notes that carbon fiber filled polyamides, such as its PA11 Carbon Fiber, warp far less and can be printed without an enclosure.

The PA12-CF sheets point the same direction but with settings very different from pure nylon. Polymaker lists a 260 to 300 °C nozzle, a bed of 25 to 50 °C that must not be exceeded, a chamber likewise capped at 50 °C, a print speed of 30 to 60 mm/s and the cooling fan off. Fiberon PA12-CF10 lists 280 to 300 °C at the nozzle, a 40 to 50 °C bed, a room-temperature chamber and the fan off.

The bed difference is striking: 110 °C at Prusa for generic nylon versus a 50 °C ceiling for these carbon PA12 grades. The PolyMide document explains that its Warp-Free technology relies on fine control of the microstructure and crystallization behavior of nylon; the Fiberon sheet only says that carbon fiber reinforcement and Warp-free technology enhance the size stability of prints. Do not carry a profile from one to the other. If you print PA6 or an unfilled nylon, the page on 3D printer enclosures explains why ambient temperature matters so much.

Drying, storage, nozzle and annealing: the published protocols

Three drying protocols appear in the sources, and they are not interchangeable. Prusa advises at least 4 hours at a temperature below 90 °C for polyamide in general. Polymaker specifies 80 °C for 12 hours in a convection oven for a PA12-CF that has picked up moisture, adding that the filament ships with the right moisture content and that an extremely dry filament can also hurt processability. Fiberon recommends 100 °C for 10 hours and storage below 20% relative humidity.

A suitable dryer helps track the time and temperature specified for the exact grade. The filament dryer guide distinguishes those settings from air humidity readings: a dry-air measurement inside a box does not measure water content in the filament. Find the protocol for your actual spool and check whether the dryer can follow it.

Both PA12-CF sheets stress the nozzle. Polymaker states that its PA12-CF contains 10% chopped carbon fiber by weight and can damage a brass nozzle after a few hundred grams. Fiberon is more specific and puts brass nozzle life at roughly 9 hours with its PA12-CF10. Finally, both sheets recommend annealing to reach the published properties: 80 °C for 6 hours at Polymaker, where tensile strength rises from 43.55 to 71.63 MPa, and 100 °C for 16 hours at Fiberon. The nozzle guide covers abrasion-resistant options.

Which family fits your part

For a stiffness requirement after water exposure, examine the published comparisons before selecting a grade. Polymaker calls its PA12-CF changes minimal against PA6-CF after 3 days of immersion. Fiberon measures 1.5 % equilibrium uptake at 23 °C and 70 % RH without a mechanical test at that condition; its wet mechanical values after 48 hours at 60 °C decrease, including 77.4 to 71.7 MPa in XY tensile strength and 52.2 to 42.1 MPa along Z. Fiberon claims lower moisture sensitivity than PA6/PA66 for its product. These findings concern the cited carbon grades and protocols; they do not predict a real part's stiffness or that of every unfilled PA6 or PA12.

If you are counting on dry values and you control storage, PA6 may remain a candidate, but the supplied sources contain no complete PA6 data sheet to quantify any such advantage. Polymaker's chart suggests a wider gap between dry and wet for PA6-CF, without a detailed protocol. Treat that as a trend, not a comparable measurement.

In both cases, three points are non-negotiable according to the sheets: filament dried per the manufacturer's protocol, an abrasion-resistant nozzle for any carbon grade, and annealing when the sheet calls for it. None of the sources guarantees behavior in a critical application, and each manufacturer places responsibility for validating the part on the user.

Sources and limits

• Prusa — Polyamide (Nylon)
• Polymaker PolyMide PA12-CF — PIS V1
• Polymaker Fiberon PA12-CF10 — TDS V1.1

We organize manufacturer and community documentation; we have not measured these products ourselves. The manual for your exact model takes precedence over general guidance.