Moisture is the most common reason good filament produces bad parts. Every spool you own is slowly pulling water out of the air, and once that water is inside the plastic it turns to steam the instant it reaches the hot end. That steam is what causes stringing, popping, weak layers, rough surfaces, and parts that measure wrong.
The frustrating part is that wet filament looks completely normal on the spool. The fix is simple and repeatable: dry the filament before you print, and keep it dry between jobs. This guide walks through how to dry filament correctly, which materials care most, and the exact temperatures and times to use.
The short version: how to dry filament
Drying temperature and time are material-specific, so always follow the settings recommended for your particular filament. For detailed guidance by material, see our filament drying instructions.
Nylon and PVA absorb water fastest. PC, PETG, PEEK, and TPU all print better dry.
Store filament with fresh desiccant in a sealed box, ideally below 15 percent relative humidity, or run hygroscopic materials straight from a heated dryer.
Why moisture is the enemy of a good print
Most engineering plastics are hygroscopic, which means they absorb water directly from the air. The water works its way into the filament and sits there until you print. At the nozzle, temperatures of 200 C and higher flash that trapped water into steam. The steam expands inside the melt, disrupts the flow, and escapes through the surface of the part.
Some polymers, including nylon and PET-based materials, can also break down slightly through a reaction with water at print temperature, which weakens the plastic itself. That damage is not reversible by drying. Once the polymer chains have shortened, the strength is gone, which is why prevention beats recovery on engineering materials.
That single mechanism, water turning to steam, shows up as several different print defects:
- Stringing and oozing. Steam pushes extra material out of the nozzle during travel moves, leaving thin hairs across the print.
- Popping and crackling. You can often hear wet filament. The snaps and pops are pockets of steam bursting as they exit the hot end.
- Weak layer adhesion. Steam bubbles interrupt the bond between layers, so parts print brittle and split along the layer lines under load.
- Surface defects. Bubbles bursting through the extrusion leave a rough, cloudy, or pitted surface with blobs and zits.
- Dimensional drift. Uneven flow from moisture makes wall widths and feature sizes inconsistent, so parts miss spec.
Which filaments are hygroscopic, and how long they last out of the bag
Every material absorbs moisture at a different rate. The more advanced the polymer, the more it usually cares. Here is how the common families rank, from thirstiest to most forgiving:
- Worst: Nylon (PA) and PVA. These can pick up enough moisture to affect a print within a few hours of sitting out in a humid room. Treat them as always needing drying.
- High sensitivity: PC (polycarbonate), PEEK, PEKK, PEI/Ultem, and TPU. These absorb quickly and print noticeably worse when wet. Dry before every serious print.
- Moderate: PETG, PCTG, ABS, and ASA. These tolerate more time in the open but still string and lose surface quality once they take on water.
- Most forgiving: PLA. PLA can go longer between drying cycles, but it is not immune. Old, humid PLA gets brittle and strings.
- Drying not required: HIPS, LTS2, and PVDF, though sealed storage never hurts.
Do carbon fiber and glass fiber grades dry differently?
Reinforced grades take their moisture behavior from the base polymer. A carbon-filled nylon is still a nylon, so dry it like one, though the filled grades often call for a slightly higher temperature than the unfilled version.
Nylon 12 dries at 80 C, while Nylon 12+CF and Nylon 12+GF30 both want 90 C. Check the specific grade rather than the family.
How long does filament last out of the bag?
As a rough rule for humid environments:
- Nylon and PVA: hours to a day before print quality suffers.
- PC, PETG, and TPU: a few days at most.
- PLA, ABS, and ASA: a week or more, though old, damp PLA still turns brittle and strings.
When in doubt, dry it. Drying a spool that did not need it costs you four hours. Printing a spool that did costs you the part.
How to dry filament: the basic method
The rules for drying filament are the same for every material. Only the temperature and time change.
- Identify the material and its safe drying temperature. Use the table below. The target is always below the plastic softening point so the spool holds its shape.
- Set a filament dryer or oven to that temperature. Accuracy matters more than raw heat. A few degrees too hot can fuse a spool.
- Dry for at least 4 hours, giving saturated spools or high-performance polymers the longer end of the range. When in doubt, refer to the drying time recommended by the filament manufacturer.
- Print straight from the dryer, or move the spool to a sealed box with desiccant. Hygroscopic materials begin reabsorbing water the moment they cool in open air.
That process answers the two questions we hear most:
- Can you use PETG without drying? Sometimes, if the spool is fresh and you store it well, but PETG strings badly once it takes on moisture, so drying is the reliable choice.
- Can you use nylon without drying? No. Nylon almost always needs drying first, which is why how to dry nylon filament is the question we get asked more than any other.
Filament drying temperatures and times by material
The values below come from the 3DXTech full filament drying guide. Times are a baseline for a spool in normal condition. Material that has been open for weeks, or stored in a humid space, needs longer.
| Material | Dryer temperature | Time |
| PPSU, PSU | 150 C / 302 F | 8 hours |
| PEI / Ultem 1010, ESD-PEI 1010 | 150 C / 302 F | 4 to 6 hours |
| PEEK, PEEK+CF10, PEEK+GF20 | 150 C / 302 F | 3 hours |
| PEI / Ultem 9085, PEI 9085+CF | 130 C / 266 F | 4 to 6 hours |
| PEKK-A, PEKK-A+CF | 120 C / 248 F | 6 to 8 hours |
| PC, PC-ABS | 120 C / 248 F | 4 hours or more |
| PC+CF, ESD-PC, PEI+GF30, PES, HTN+CF, HTS1, HTS2 | 120 C / 248 F | 4 hours |
| PPS | 110 C / 230 F | 4 hours |
| Nylon 6 | 90 C / 194 F | 4 to 6 hours |
| Nylon 6 Alloy, Nylon 6+CF, Nylon 6+GF30, Nylon 6-66, Nylon 12+CF, Nylon 12+GF30 | 90 C / 194 F | 4 hours |
| FR-PC/ABS, Obsidian Nylon 6+CF V2 | 80 C / 176 F | 6 hours |
| ABS, ABS+CF, ABS+GF, ASA, ASA+CF, ESD-ABS, FR-ABS, ezPC, ezPC+CF, MTS1, Nylon 12, PPE/PS | 80 C / 176 F | 4 hours |
| Obsidian FR-Nylon | 70 C / 158 F | 6 hours |
| PETG, PETG+CF, EMI-PETG, ESD-PETG, R-PETG, PCTG, PLA+CF, Tough PLA, ESD-PLA, PVA, TPU 85A, TPU 95A, ESD-TPU 60D, PP+CF, Simubone | 65 C / 149 F | 4 hours |
| PLA, Economy PLA, Glitter PLA, Satin PLA | 45 C / 113 F | 4 hours |
| HIPS, LTS2, PVDF | Drying not required | n/a |
Note: set the dryer to the listed temperature, not higher. Overshooting the softening point deforms the spool and can jam your feed path.
Why these numbers differ from other drying charts
You will see lower temperatures quoted elsewhere, often 70 to 80 C for nylon. Those figures come from generic material charts that average across every brand on the market.
The values above are the ones 3DXTech publishes for its own polymers, validated against the specific grades and spool geometry we ship. Use these numbers for 3DXTech material.
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Not sure your setup can hold these temperatures? Most kitchen ovens cannot run accurately at 45 to 90 C, and few reach engineering-grade drying temperatures safely. The 3DXTech FD1 Filament Dryer holds precise temperatures across the full material range and lets you print straight from the chamber. |
How to dry nylon filament
Nylon is the material that punishes moisture the most, so it is worth a closer look. The right temperature depends on the grade:
- Nylon 6, Nylon 6 Alloy, Nylon 6-66, and the carbon and glass filled nylons: 90 C for 4 hours.
- Plain Nylon 12: 80 C for 4 hours.
- Obsidian FR-Nylon: 70 C for 6 hours. Obsidian Nylon 6+CF V2: 80 C for 6 hours.
A spool that has been open for weeks, or one that already prints fuzzy and weak, may need significantly longer to fully dry out — check the manufacturer's guidance for the recommended time.
Why drying nylon once is not enough
Because nylon reabsorbs water so quickly, drying it once is not enough. Keep the spool in the dryer while you print, or move it to a sealed container with fresh desiccant between jobs.
If parts still come out brittle or hairy after a proper drying cycle, the spool almost certainly picked up moisture again before or during the print. The same discipline applies to PVA supports, which fail even faster when wet.
Drying filament versus storage: keeping spools dry between prints
Drying and storage solve two different halves of the same problem. Drying removes water the filament has already absorbed. Storage stops it from coming back. You need both.
- Dry boxes. A sealed container keeps humidity away from the spool between prints and during long jobs. Many shops feed filament from a dry box straight into the printer. Vacuum bags work for spools you are not printing from.
- Desiccant. Silica gel packs inside the box pull ambient moisture out of the air. Recharge or replace them regularly, because saturated desiccant does nothing.
- Measure it. A cheap digital hygrometer inside the box tells you whether the desiccant is still working. Aim to keep storage below 15 percent relative humidity. Without a reading you are guessing, and saturated silica gel looks exactly like fresh silica gel.
- Printing from a dryer. For nylon, PC, PEEK, and other thirsty materials, the most reliable approach is to keep the spool warm and dry throughout the print, not just before it.
For shops running hygroscopic materials continuously, a heated maintainer removes the guesswork. The FM1 Filament Maintainer keeps material at temperature and feeds it directly to the printer, so the filament never sits in open air long enough to matter.
Is my filament wet? A quick diagnostic
If a print is going wrong, moisture is one of the first things to rule out. Match the symptom to the likely cause, apply the fix, and use the linked 3DXTech guide for the full walkthrough.
| Symptom | What it means | Fix | 3DXTech guide |
| Stringing or thin wispy hairs between parts | Water flashing to steam at the nozzle | Dry the spool, then retune retraction | Stringing and Oozing |
| Popping, crackling, or visible steam at the hot end | Trapped moisture boiling off as it prints | Stop, dry the spool fully, then reprint | Under-Extrusion |
| Weak, brittle layers that snap apart | Steam disrupting the layer-to-layer bond | Dry the spool to the table temperature, then raise print temperature or flow if the bond is still weak | Layer Bonding |
| Rough or cloudy surfaces, blobs, and zits | Bubbles bursting through the extrusion | Dry the spool and clean the nozzle | Blobs, Zits, Surface Defects |
| Filament snapping in the feed path or grinding at the drive gears | Old, dry-brittle or moisture-damaged filament losing flexibility | Dry the spool, then back off extruder tension and check for a partial clog | Grinding Filament at Drive Gears |
| Parts measuring off spec or uneven walls | Inconsistent flow caused by moisture | Dry the spool, then verify calibration | Dimensional Accuracy |
| Corners lifting or cracking on large parts | Usually warping, made worse by wet nylon or PC | Dry first, then address bed and enclosure | Warping |
If you are chasing several of these at once, start with the 27 common FDM printing problems overview, then dry the spool before you change any other settings. Drying first saves you from retuning a printer that was never the problem.
Do you need a filament dryer, or is an oven fine?
Can you dry filament in an oven?
An oven can work as a stopgap, but it has three real drawbacks:
- Poor accuracy at low temperatures. The dial might say 80 C while the interior swings 20 degrees in either direction, which is enough to soften or fuse a PLA or PETG spool.
- No airflow control. There is nothing to carry the released moisture out of the cabinet, so it can settle back into the filament as the oven cools.
- Not built for long unattended cycles. An 8 hour run in a kitchen oven is not something you want to walk away from.
If you use one anyway, verify the true temperature with a separate oven thermometer and stay well below the material softening point.
What about a food dehydrator?
Dehydrators come up often as a cheaper option, and they do hold low temperatures more steadily than an oven. The catch is the ceiling.
Most top out near 70 C, which covers PLA, PETG, and TPU but leaves out nylon, PC, PEKK, PEEK, and Ultem entirely. If you only print PLA and PETG, a dehydrator is a workable budget tool. If you print anything engineering-grade, it cannot reach the temperatures the material needs.
Why a dedicated dryer wins
A dedicated filament dryer solves all of that. It holds accurate low temperatures, moves air to carry moisture out, and is built to run safely for long cycles. For engineering and high-performance materials, that precision is the difference between a dry spool and a warped one.
The 3DXTech FD1 Filament Dryer covers the full temperature range these materials need, and the FM1 Filament Maintainer extends that into continuous, print-from-dryer use.
The short answer: an oven is fine for the occasional emergency on high-temperature materials, but if you print nylon, PC, PEEK, or anything filled on a regular basis, a real dryer pays for itself in saved prints and material.
Frequently asked questions
How do I dry 3D printer filament, and at what temperature?
Set a filament dryer or accurate oven to the temperature for your material, then run it for at least 4 hours. The 3DXTech temperatures are:
- PLA: 45 C
- PETG, PCTG, TPU, and PVA: 65 C
- ABS, ASA, and Nylon 12: 80 C
- Nylon 6 and the carbon and glass filled nylons: 90 C
- PPS: 110 C
- PC, PES, and PEKK: 120 C
- PEI / Ultem 9085: 130 C
- PEEK, PEI / Ultem 1010, PPSU, and PSU: 150 C
Always stay below the plastic softening point so the spool holds its shape.
Can you use PETG without drying?
You can print a fresh, well-stored PETG spool without drying, but PETG absorbs moisture over time and strings badly once it does. If you see stringing, bubbling, or a cloudy surface, dry it at 65 C for 4 hours and the problem usually clears.
Can you use nylon without drying?
No, not reliably. Nylon absorbs moisture faster than almost any other filament and can take on enough water to ruin a print within hours of sitting out in a humid room.
Dry Nylon 6 and the filled grades at 90 C, or plain Nylon 12 at 80 C, for at least 4 hours before printing, and keep the spool in the dryer or a sealed box with fresh desiccant during the job.
Which filaments need drying, and how long do they last out of the bag?
Nylon and PVA need drying almost every time and can suffer within hours in a humid room. PC, PETG, PEEK, and TPU are highly sensitive and last a few days at most. ABS, ASA, and PLA are more forgiving and can go a week or more, though PLA still gets brittle when old and damp. HIPS, LTS2, and PVDF do not require drying.
Why is my print stringing, popping, or failing on layer adhesion?
All three are classic signs of wet filament. Water trapped in the spool flashes to steam at the nozzle, which pushes out stringing, makes popping sounds, and interrupts the bond between layers so parts turn brittle. Dry the spool to the correct temperature before you change any slicer settings, then re-tune if needed.
Do I need a filament dryer, or is an oven fine?
An oven can work in a pinch for high-temperature materials if you verify the real temperature, but most ovens are inaccurate at low settings and can ruin PLA or PETG spools. A food dehydrator holds low temperatures better but usually stops around 70 C, so it cannot dry nylon, PC, or any of the high-performance polymers. A dedicated dryer holds precise temperatures, controls airflow, and runs safely for long cycles, which makes it the reliable choice for anyone printing engineering materials regularly.
Stop losing prints to moisture
Wet filament is the easiest print failure to prevent. Knowing how to dry 3D printer filament comes down to three habits: match your material to the drying table, dry before you print, and store spools with fresh desiccant and a hygrometer to prove it is working, or run them straight from a heated dryer. Do that consistently and stringing, popping, and weak layers largely disappear.
If you print advanced materials, give them the drying they need. Explore the 3DXTech FD1 Filament Dryer and the FM1 Filament Maintainer, and bookmark the full drying guide for the exact temperature and time for every material we make.
