Nylon Filament Guide: Properties, Settings, and Best Uses

When someone asks me "what's the strongest filament I can print?" the answer is almost always nylon. Not PLA (too brittle), not PETG (too soft under load), not ABS (decent but outclassed). Nylon-specifically the polyamide family (PA6, PA12, and their carbon-fiber variants)-offers a combination of tensile strength, impact resistance, and fatigue life that nothing else in the FDM filament world can match. The catch? Nylon is genuinely difficult to print well.

I've spent six months testing four different nylon formulations on my enclosed Bambu Lab P1S, and the data tells a clear story: nylon rewards meticulous preparation and punishes shortcuts. Here's the complete guide to getting it right.

Understanding Nylon Types: PA6 vs PA12 vs PA-CF

Not all nylon is the same. The "PA" designation (polyamide) followed by a number indicates the chemical structure, and each variant has distinct printing and performance characteristics:

PA6 (Nylon 6): The original industrial nylon. Highest strength and stiffness of the PA family, with excellent wear resistance. But it's the hardest to print-extreme moisture absorption, aggressive warping, and it requires nozzle temperatures of 260–280°C with bed temps of 90–110°C. PA6 is what you reach for when mechanical performance is the absolute priority and you're willing to fight the printing process.

PA12 (Nylon 12): The "easy nylon." Lower moisture absorption than PA6, significantly less warping, and prints at a more moderate 240–260°C. Mechanical properties are slightly lower than PA6 (about 15–20% less tensile strength) but still dramatically superior to PETG or ABS. PA12 is my default recommendation for anyone trying nylon for the first time. Polymaker PolyMide PA12 and Bambu Lab PA6-CF (which despite the name behaves closer to PA12 in printing difficulty) are excellent starting points.

PA-CF (Carbon Fiber Nylon): Nylon reinforced with chopped carbon fibers. The carbon fibers increase stiffness by 50–80% compared to unfilled nylon and reduce warping significantly (the fibers constrain shrinkage). The tradeoff is reduced impact resistance-CF nylon is stiffer but more brittle than pure nylon. Also, carbon fiber is abrasive: you need a hardened steel or ruby nozzle. A brass nozzle will be destroyed within 200–300g of CF nylon.

The Moisture Problem: Why Drying Is Non-Negotiable

Nylon is hygroscopic-it actively pulls moisture from ambient air. PA6 can absorb up to 9% of its weight in water, and even PA12 absorbs 1.5–2%. This isn't a minor concern you can ignore-wet nylon is effectively unprintable.

When wet nylon hits the 250°C+ hotend, the absorbed water turns to steam and creates bubbles in the molten plastic. You'll hear popping sounds during extrusion, and the printed surface will be covered in tiny craters, pits, and rough patches. Layer adhesion drops by 30–50% because the steam disrupts the bond between layers. Dimensional accuracy goes out the window because the steam expands the extrusion unpredictably.

Drying protocol: Every spool of nylon must be dried before first use AND kept dry during printing. My protocol:

Initial drying: 70–80°C for 6–12 hours in a filament dryer. PA6 needs the full 12 hours. PA12 is usually good after 6–8 hours. I use a Sunlu FilaDryer S2-it hits 70°C reliably and holds a full spool. A food dehydrator also works if it can reach 70°C.

During printing: Print directly from a dry box. I use a sealed container with a PTFE tube running from the container to the printer's filament sensor. Desiccant packs inside the container keep humidity below 15% RH. If you don't have a dry box, at minimum keep the spool in a sealed bag with desiccant and only take it out for the duration of the print.

Between prints: Reseal the spool in a vacuum bag with fresh desiccant immediately after printing. Nylon left on a shelf in average indoor humidity (40–60% RH) absorbs enough moisture to degrade print quality within 24–48 hours. This is not an exaggeration-I've measured it.

Print Settings: Dialed In After 50+ Test Prints

These settings represent my optimized configuration after extensive testing. Treat them as starting points and adjust based on your specific nylon brand and printer:

Nozzle temperature: 250–270°C for PA12, 260–280°C for PA6, 260–275°C for PA-CF. Start at the lower end and increase if you see under-extrusion or poor layer adhesion. Too hot causes stringing and oozing (nylon is extremely stringy at high temperatures).

Bed temperature: 80–100°C. PA12 sticks well at 80°C on textured PEI. PA6 needs 90–100°C and benefits from a bed adhesive (glue stick or Magigoo PA).

Print speed: 40–60 mm/s. Nylon's slow solidification rate means it needs more time between layers to set properly. I run 50 mm/s as my baseline for PA12 and 40 mm/s for PA6. PA-CF can handle slightly higher speeds (up to 70 mm/s) because the carbon fibers speed up solidification.

Enclosure: Required for PA6 and strongly recommended for PA12. Maintain 40–55°C ambient temperature inside the enclosure. PA-CF is the most forgiving-small parts print fine without an enclosure, though large parts still benefit from one.

Cooling fan: 0–20%. Like ASA, nylon needs slow cooling for good layer adhesion. I run 0% fan for the entire print on PA6 (enclosed printer), and 10–15% for PA12 on overhangs only.

Retraction: Nylon strings aggressively. Use retraction distance of 1–2 mm (direct drive) or 4–6 mm (Bowden) at 40–60 mm/s retraction speed. Even with optimized retraction, expect some stringing-a heat gun at low setting cleans it up in seconds after printing.

Bed Adhesion: The Warping Battle

Nylon warps. Not as bad as ABS, but significantly more than PLA or PETG. The warping comes from crystallization shrinkage as the polymer cools-nylon shrinks 1.5–2% during cooling, which creates enormous internal stress that peels corners off the bed.

Textured PEI + glue stick: My preferred combo for PA12 and PA-CF. The glue stick (Elmer's purple) creates a release layer that prevents the nylon from bonding permanently to the PEI while still holding during printing. Without glue stick, PA12 on PEI bonds so strongly that removal can damage the PEI surface.

Garolite (G10/FR4) sheet: The gold standard for PA6 adhesion. Garolite is a fiberglass-reinforced laminate that has a chemical affinity for nylon. Parts stick firmly during printing at 100°C bed temp and release cleanly when cooled. A 300x300 mm Garolite sheet costs $15–20 and lasts essentially forever. If you print PA6 regularly, this is worth the investment.

Brim: Always use a brim of at least 5 mm (I use 8 mm for PA6). The brim increases the contact area with the bed, resisting the warping forces. Remove it after printing with a deburring tool or knife. For large flat parts, increase to 12–15 mm brim.

When Nylon Beats Everything Else

Nylon isn't the right choice for every print. It's harder to print, more expensive ($35–60/kg vs $20 for PLA), and requires dedicated preparation. But for specific applications, nothing else comes close:

Living hinges and snap fits: Nylon's fatigue resistance is extraordinary. A snap-fit clip printed in nylon can be flexed thousands of times without cracking. The same clip in PLA fails in 5–10 cycles, and PETG lasts 50–100. If your part needs to flex repeatedly, nylon is the answer.

Gears and bearings: Nylon's natural lubricity (low friction coefficient) makes it excellent for gears that mesh with other plastic or metal gears. It's the same reason injection-molded nylon gears are used in automotive timing systems, power tools, and robotics. A 3D-printed nylon gear running against a metal shaft will outlast PETG or ABS by 10x or more.

Impact-resistant enclosures: Drop a PLA enclosure and it shatters. Drop a PETG enclosure and it cracks. Drop a nylon enclosure and it bounces. For protective cases, drone frames, robot chassis, and anything that takes physical abuse, nylon absorbs impacts without fracturing.

Chemical exposure: Nylon resists oils, greases, fuels, and most organic solvents better than any other common FDM filament. Automotive parts, chemical handling tools, and industrial fixtures in nylon hold up in environments that would degrade other plastics.

PA-CF: The Best of Both Worlds?

Carbon fiber nylon deserves its own section because it's becoming the go-to material for advanced functional printing. The carbon fibers (typically 10–20% by weight, chopped to 100–200 micron lengths) transform nylon's properties:

Stiffness: PA-CF is 50–80% stiffer than unfilled nylon. Parts feel rigid and solid-more like a machined engineering plastic than a 3D print. Deflection under load is minimal.

Warping reduction: The fibers constrain shrinkage during cooling, reducing warp by roughly 60% compared to unfilled PA6. This makes PA-CF the most printable high-performance nylon variant. I've successfully printed 200x200 mm flat parts in PA-CF without warping-something I can't reliably do with unfilled PA6.

Surface quality: PA-CF produces a matte, slightly textured surface that hides layer lines better than any other filament I've tested. Parts look professional straight off the printer with zero post-processing. The matte finish is visually similar to injection-molded nylon parts.

The cost: PA-CF typically runs $45–65/kg, roughly 2x the cost of unfilled PA12. Plus you need a hardened steel nozzle ($10–15) that you replace every 3–5 kg. The total cost per part is significant, so reserve PA-CF for parts where its properties are actually needed-high-stiffness brackets, load-bearing tools, and production-quality prototypes.

My Nylon Workflow in Practice

Here's my actual workflow for a nylon print from start to finish:

Day before: Pull the nylon spool from its vacuum-sealed bag, load it into the filament dryer at 75°C, and run it overnight (8–12 hours). Transfer the dried spool to the dry box the next morning.

Print setup: Apply glue stick to the PEI bed (or use the Garolite sheet for PA6). Load the filament from the dry box through the PTFE tube. Preheat the enclosure by running the bed at 100°C for 10 minutes with the enclosure doors closed. This stabilizes the ambient temperature before the first layer goes down.

During print: Monitor the first 3–5 layers closely. If warping starts, increase bed temp by 5°C. If adhesion is too strong, add another layer of glue stick (it paradoxically acts as a release agent when applied thickly). After the first 5 layers, nylon prints are generally stable-warping that's going to happen shows up early.

Post-print: Let the part cool to room temperature on the bed. Nylon parts removed hot will warp from thermal shock. Once cool, flex the PEI sheet to release. Clean up the brim with a deburring tool. For PA-CF, a quick pass with 220-grit sandpaper on the brim edge gives a finished look.

Storage: Immediately reseal the spool in a vacuum bag with 2–3 fresh desiccant packs. Label the bag with the date so you know how long it's been sealed. Nylon stored this way stays printable for months.

Nylon demands more preparation, more attention, and more money than any other FDM filament. But the parts it produces are in a completely different category of strength, durability, and professional quality. Once you print a nylon gear that actually runs under load, or a snap-fit enclosure that survives repeated drops, you'll understand why engineers reach for polyamide when the part needs to perform-not just exist.