Nylon problems: wet filament, warping, adhesion, stringing

This guide is for nylon (PA) prints that pop and bubble, string, curl off the plate, won't stick, or come out weaker or softer than expected. It collects what Polymaker, Bambu Lab, Prusa, ELEGOO and SUNLU say about their own nylon, and keeps each setting to the product the maker names. It's the troubleshooting companion to our nylon filament guide, which has every maker's full drying, bed, nozzle and enclosure tables, so this page links there rather than repeating them. Start here:

Wet filament: dry first

Every maker here calls for drying nylon. The signs of a wet spool they describe:

• Polymaker: "If you hear "popping" or "cracking" noises, then the filament needs to be dried." It says its PA-CF "should only be printed while kept in a heated filament dryer the entire time you print."
• Prusa: "Moist polyamide filament makes bubbles, which leads to uneven layers and an ugly surface." It says improper storage "can lead it to absorb water weighing up to 10% of filament weight." Its drying article adds that high water content "can cause low layer adhesion, blobs on the prints, and bubbling and smoke during extrusion."
• Bambu Lab: "Nylon and PC absorb moisture within hours in a humid environment — never leave them on the spool holder overnight." It says PA-based filaments left in open air for around three months take up so much moisture that "it becomes very difficult to dry them using a conventional convection oven at 80–90 °C," so a spool you won't use for a while "must be protected with desiccants and stored in a sealed container."
• SUNLU PA12-CF: "After 6 hours of unpacking, drying is required before printing."
• Prusament PA11: print quality deteriorates once absorbed humidity gets high, and "Deterioration occurs between a few days and a month."

The settings differ a lot between makers, from Prusa's general advice of "at least 4 hours at a temperature below 90 °C" to 100 °C for 10 hours for Polymaker's Fiberon nylons and 80 °C for 24 hours or 110 °C for 4 hours for SUNLU PA6-CF. Bambu and ELEGOO give 80 °C for 8–12 hours and 80 ± 5 °C for 8 hours for their PAHT-CF. Use the setting for your exact spool, and check what its spool can take: Bambu cites 80–90 °C as within its own spool's limit, and Prusa says its black spool resists drying temperatures up to 90 °C. Our nylon guide's drying table lists every maker's setting.

Keeping it dry while it prints matters as much. Bambu's PAHT-CF usage guide recommends "a dry box or an enclosed feeding system such as the AMS," and Polymaker's PA guide says nylon "Should be kept in dryer entire time being printed." Our wet filament guide covers how to tell if a spool is damp, and our dryer vs dry box guide covers the equipment. If you don't have a dryer yet, our filament dryer shortlist compares them.

Stringing and oozing

Bambu Lab is the one maker here that addresses nylon stringing directly, and it points to moisture first. Its PAHT-CF usage guide says "When the filament absorbs moisture, the internal water vaporizes at high temperatures, disrupting the melt flow stability. This results in stringing, oozing, and uneven surface texture." For leakage, it says to "first follow the drying procedure." Its filament guide lists stringing, under-extrusion, holes, rough surfaces and reduced strength as the results of printing damp filament.

Once the spool is dry, these are the retraction starting points makers publish for their own nylon:

Prusa notes that "Some filaments are naturally more stringy than others," and says to compare results across your prints. Our stringing guide covers temperature towers and retraction tests for any material.

How do you stop nylon from warping?

Prusa says that "Apart from moisture issues, the main disadvantage of pure polyamide is warping." Bambu's warping guide ranks PA-CF and PA second and third in its list of shrinkage-prone filaments, after PC and ahead of ABS. But the makers fix it in opposite ways, depending on the product:

What else the makers suggest for lifting parts:

• Bambu Lab (PAHT-CF usage guide): clean the plate and apply its glue stick, enable a brim, and on printers with active chamber heating, use it. When the room is cold, it says the X1C and P1S should "preheat the bed to the maximum temperature and wait 15 minutes before starting the print." It says to "Avoid using a fill rate above 50% to reduce material shrinkage," and that "the default 2 walls + 15% infill is sufficient" for most non-structural parts.
• Bambu Lab (warping guide): in a room below 20 °C, it says that for ABS, ASA, PA and PC "an enclosed printer with a heated chamber is essential," and that on an open-frame printer such as the A1 you should raise the bed by an additional 10 °C. Its A1 FAQ doesn't recommend PA on the A1 for large or high-infill models that need strong layers, but says such materials "can be used on A1 for printing small-sized models with low infill densities."
• Prusa: "High ambient temperature (enclosure) helps a lot." It says carbon-fiber-filled polyamides "don't warp by far as much as the unaltered versions and can be printed without an enclosure." Answering a reader's warping question, a reply marked "Official Prusa CS" suggests printing "a skirt a few more layers higher than normal, so that it absorbs the warping issues."
• Prusament PA11 Carbon Fiber (data sheet): "The brim is recommended for larger objects."
• SUNLU PA12-CF: "It is recommended to apply glue to assist printing to prevent warping."

Our warping guide covers plate cleaning, first-layer checks and drafts for any material, and our enclosure planning guide covers what an enclosure does and doesn't do.

Plates, glue and adhesion

Every maker here pairs nylon with either a dedicated sheet or glue:

• Prusa: "The special PA Nylon sheet will provide the best adhesion for most polyamides." Clean it with water only: the PA11 page says "This print sheet gets damaged when cleaned with isopropyl alcohol, acetone, or other chemicals." For PA11 Carbon Fiber on standard PEI sheets with glue stick, Prusa says "Large prints will tend to warp, small prints won't stick to the print surface."
• Prusament PA11 can stick too hard. "PA11 adheres strongly to the PA Nylon Sheet. We recommend applying a thin separation layer to prevent any damage, especially when printing large components." For PA11 Carbon Fiber, Prusa says "We don't recommend any other surface preparations" beyond cleaning with water.
• Bambu Lab: its glue stick for PA6-GF/CF and PAHT-CF. The PAHT-CF page says it's "Not compatible with Cool Plate SuperTack, Hotend with Stainless Steel Nozzle 0.2 mm, and Bambu Liquid Glue," and the filament guide marks the Cool Plate "Not recommended" for PA.
• ELEGOO PAHT-CF: build plate glue "Required," on "Textured/Smooth PEI or Other Plates."
• SUNLU PA6-CF and PA12-CF: textured PEI with "Glue stick / LAC spray adhesive" (data sheets).
• Polymaker Fiberon PA6-CF20 and PA612-CF15: "Use glue stick or Magigoo PA if bed adhesion is weak," on a 40–50 °C plate.

Bambu's own bed figures for PA don't agree. Its PAHT-CF and PA6-CF data sheets say 80–100 °C, its filament guide's glue table says 90–110 °C, and its plate table says 100–120 °C. Start from the data sheet for the exact spool. Our bed adhesives guide and first-layer adhesion guide cover the general checks.

Fan and layer bonding

If layers split, Bambu's interlayer cracking guide names PA-CF among the materials where it's common. Its steps are to clear any partial clog, raise the nozzle temperature or slow down, reduce the part cooling fan, and raise the bed by 5–10 °C (and the chamber by 5 °C on printers with active chamber heating). Prusa says a warm enclosure for PA11 "may improve layer-to-layer adhesion," and lists "Lower layer-to-layer adhesion (compared to pure PA)" as a con of PA11 Carbon Fiber. Our layer adhesion guide covers the other checks.

Which nozzle does carbon-fiber nylon need?

Fiber-filled nylon wears soft nozzles, and the makers are blunt about it:

• Bambu Lab: for PA-CF/GF, PA6-CF/GF and PAHT-CF/GF, a hardened steel nozzle is "Required." It says not to use a 0.2 mm nozzle ("The clogging risk is extremely high") or a stainless steel or brass nozzle. The PAHT-CF page says "0.6 mm Nozzle Recommended." Its A1 FAQ says the standard A1 nozzle is stainless steel and must be replaced with hardened steel for PAHT-CF/GF.
• Polymaker Fiberon: use "a wear-resistant nozzle, such as hardened steel or ruby"; the PA6-CF20 page says brass-nozzle life "may be approximately 9 hours."
• ELEGOO PAHT-CF: "0.2 mm Nozzle Not Compatible" and "0.4 mm/0.6 mm/0.8 mm Hardened Steel Nozzle Recommended."
• SUNLU: for PA12-CF, "Printing PA12-CF with copper nozzles is susceptible to wear and tear"; for PA6-CF, use "an abrasion-resistant nozzle (e.g., hardened steel)."
• Prusa: "Carbon, glass and kevlar fibers are highly abrasive, so it is necessary to use a hardened nozzle." Prusament PA11 without fiber is the exception: Prusa lists a "Standard 0.4 mm brass nozzle."

For clogs, Prusa suggests a cold pull before printing, says the first layer "should be perfectly fine, otherwise, you risk the nozzle clogging," and gives "0.4mm nozzle diameter and 0.2mm layer height" as the lowest optimal values. Bambu says fiber residue can build up in the nozzle and raise extrusion resistance, and that when switching from a high-temperature filament to a low-temperature one such as PLA, you should "always heat the nozzle to the extrusion temperature of the high-temperature filament first to purge any residue." Our abrasive filament nozzle guide, worn nozzle guide and clog diagnosis guide cover the rest. If you need a hardened nozzle for your printer, our replacement nozzle shortlist lists them by printer.

Supports

Moisture affects supports too:

• Bambu Lab PAHT-CF: "we recommend removing the support structures within 2 hours after printing to prevent them from sticking after absorbing moisture. If sticking occurs, dry the model to ease the removal." Its PA6-CF page gives the same 2-hour rule.
• Polymaker Fiberon: "If the material is used as its own support, remove the support before excessive moisture absorption to avoid permanent bonding."

Our supports hard to remove guide covers the general settings.

After printing: parts keep taking up moisture

A nylon part that prints well can still change in the days after. Polymaker says "Just as your nylon is expected to absorb moisture while on the spool, it will also absorb moisture as a final print," and that this "means your nylon print will grow slightly post annealing as it absorbs moisture," and "will get less rigid but will also become more impact resistant." Bambu Lab says its PA6-CF "will experience a decrease in strength and stiffness after absorbing water," and doesn't recommend it for parts with high strength, stiffness or dimensional-stability requirements, "especially thin and elongated models."

What the makers suggest:

• Polymaker: anneal first, then moisture condition, because "Annealing will dry your print out, so if you anneal after moisture conditioning, you will just need to moisture condition again." It lists 48 hours in a humid space, a soak in water then 48 hours in the air, or two weeks in room air.
• Bambu Lab: "Fully impregnating the surface of the prints with paint, wax and other waterproof coatings can inhibit water absorption and prevent them from becoming soft."

Our nylon guide has the makers' dry and wet strength figures, and our annealing guide covers each maker's oven cycle and the shrinkage it causes.

Fumes and handling

These are the makers' own statements. We don't add to them.

• Prusa: "Polyamides emit a strong odor with potentially dangerous ultrafine particles (UFPs) so printing in a well-ventilated room or in an enclosure is a must." For PA11 Carbon Fiber, it recommends "printing in an enclosure placed in a well-ventilated room."
• Bambu Lab PAHT-CF and PA6-CF: print "in a well-ventilated area, or install an effective air filtration or exhaust system." For PAHT-CF, it warns the filament surface and ends "may contain hard microscopic splinters invisible to the naked eye," and says to wear puncture- and cut-resistant gloves and safety goggles when handling filament, removing supports or sanding.
• SUNLU (data sheets): "The print processing area should be well ventilated," and "Local extract ventilation should be used when necessary."

A sensible order

1. Check your printer suits the spool: hotend temperature, a hardened nozzle for fiber grades, and an enclosure if the filament maker asks for one.
2. Dry the spool to its maker's setting, within what the spool can take.
3. Print from a dryer or a sealed box with desiccant.
4. Prepare the plate the way the filament maker says: PA Nylon sheet, glue stick, or both.
5. Set bed, chamber and fan from the filament maker's numbers, hot-chamber or Warp-Free, not a mix.
6. Add a brim for larger parts, and keep infill and wall counts moderate on Bambu printers.
7. If it strings, dry again before changing retraction.
8. If layers split, cut the fan, raise the nozzle temperature within range and slow down.
9. Remove supports promptly, and plan for the part to change as it takes up moisture.

Checklist

• Spool dried to its maker's setting and kept dry while printing.
• No popping or crackling at the nozzle.
• Hardened nozzle (0.4 mm or larger) for carbon-fiber nylon; no 0.2 mm nozzle.
• Plate prepared as the filament maker says, with glue where called for.
• Bed and chamber inside the filament maker's ranges: hot chamber for Bambu and ELEGOO PAHT-CF and Prusament PA11, below 50 °C with doors open for Polymaker Fiberon.
• Fan set from the filament maker's numbers.
• Brim on for larger parts.
• Supports off within 2 hours on Bambu PA prints.
• Dimensions and stiffness checked after the part has taken up moisture.
• A well-ventilated room.

How this guide was checked

This is a research-based guide. We haven't run these tests for it. Every setting, quote and recommendation comes from the Polymaker, Bambu Lab, Prusa Research, Prusa Polymers, ELEGOO and SUNLU pages and data sheets listed in the sources, retrieved on 2026-10-13. Settings are kept to the product each page names, and where makers disagree we show both. Safety statements are the makers' own. Read more in our editorial standards.

Specialty materials: what to check before you buy a spool ↗