Dry PLA at 45–55°C, PETG at about 65°C, and give both several hours. That is the short answer. The longer one depends on the material, how wet the spool is and what your dryer can actually hold, and getting it wrong can fuse a reel into a solid lump. This guide gives you the temperatures, the times, the reasoning behind them and the signs that tell you when to stop.

TL;DR

• PLA: 45–55°C, typically 4–6 hours. Keep well under its glass transition range of roughly 58–65°C.
• PETG: 65°C for at least 4 hours; heavily saturated spools can need up to double that.
• Tougher materials (ABS, ASA, TPU, nylon, PC): these tolerate and need more heat, but published settings vary by manufacturer, so start from the figure printed on your spool’s label.
• Check, don’t guess: hissing, popping, stringing and rough surfaces say the filament is wet. Store it dry afterwards or you will be repeating the job.

Table of Contents

• Why drying temperature matters at all
• The glass transition rule
• Filament drying temperature chart
• PLA drying temperature and time
• PETG drying temperature and time
• TPU, ABS, nylon and the rest
• How to tell filament is wet
• Setting a filament dryer
• Keeping filament dry afterwards
• Our view on drying
• Stock your print shelf
• FAQ
• Sources

Why drying temperature matters at all

Most common filaments are hygroscopic: they pull water vapour out of the air. Print a damp spool and the water flashes to steam inside the hot nozzle. You get bubbles, popping, wispy strings and dull, rough surfaces.

It is more than cosmetic. Industrial processors treat the problem seriously: one polymer-equipment manufacturer states that drying is not optional with PLA, because even small amounts of moisture hydrolyse PLA in the melt. Academic work on printed PLA points the same way: even low rates of moisture absorption are enough to cause bulk degradation and reduce mechanical performance, especially with heat and humidity involved.

So drying is worth doing. The temperature is the part people get wrong, and the rule behind it is simple: hot enough to drive water out, cool enough that the plastic stays rigid.

The glass transition rule

Every amorphous or semi-crystalline plastic has a glass transition temperature (Tg), the point where it stops being hard and starts to soften. For PLA, the research we cite puts Tg at roughly 60–65°C, with melting at about 173–178°C.

That gap is the whole story for PLA. A spool is wound tightly. Warm it past its Tg and the layers soften, sag and bond to each other. You will not be able to unwind it cleanly, and the diameter can become uneven even if it does unwind.

There is a second reason to stay below Tg. Lab research on polymers shows that while saturated moisture content mostly depends on relative humidity when the temperature is far below Tg, it can rise markedly once the temperature crosses the glass transition. That research was on electronics packaging polymers rather than filament, so treat it as the principle and not a spool-specific figure. The practical lesson is the same: stay under Tg and let time do the work, not heat.

Filament drying temperature chart

The table below gives working ranges. PLA and PETG figures are backed by the sources linked in this guide. For the other materials, published numbers differ between manufacturers and dryer makers, so the ranges are typical starting points, not guarantees. If your spool has a drying recommendation on the box or label, that wins.

Material	Typical drying temperature	Typical time	Notes
PLA	45–55°C	4–6 hours	Never approach 60°C; Tg is the ceiling
PETG	65°C	4 hours minimum	Wetter spools can need up to 8 hours
ABS / ASA	Roughly 70–80°C	4–7 hours	Check the label; more tolerant of heat
TPU	Roughly 55–70°C	6–8 hours	Soft and absorbs moisture readily
Nylon (PA)	Roughly 70–95°C	8–16 hours	Needs a dryer that reaches high temperatures
PC	Roughly 70–80°C	6–8 hours	Often printed from the dryer

Those ranges reflect what widely circulated drying guides tend to show. Use the lower end when you are unsure, and extend the time instead of raising the heat.

PLA drying temperature and time

Aim for 45–55°C. Most people settle on 50°C and leave it for 4–6 hours. Our own guide on drying silk PLA for 4–6 hours lands in the same window.

Why not hotter to go faster? Because PLA spools deform. Some old advice online says to dry PLA at 80–100°C. That figure comes from industrial pellet drying, where loose granules pass through a desiccant dryer before moulding. One thesis in our sources describes PLA pellets dried at 100°C overnight before injection moulding. Pellets in a hopper cannot fuse into a reel. A wound spool can. Do not copy industrial pellet settings onto a desktop spool.

A good PLA routine:

1. Set the dryer to 50°C.
2. Run it for 4 hours, then check the filament by feel and by a short test extrusion.
3. Add another 2 hours if it still pops or strings.
4. Let the spool cool in the dryer before you remove it, and seal it right away.

PETG drying temperature and time

PETG tolerates more heat than PLA, and it needs it. The iDryer settings page for PETG lists 65°C as the dryer temperature and 4 hours as the minimum recommended time, with a target of under 15% humidity inside the dryer. The same source notes that heavily saturated spools can need up to double the standard duration.

So for PETG:

• Start at 65°C.
• Plan on 4 hours for a spool that is only slightly damp.
• Plan on 8 hours for one that has sat open for weeks, or that hisses when it prints.

PETG is also the material most people notice going wet first, because the symptoms are so obvious: fine hairs between features and a cloudy, matt finish. If you print with it regularly, our Sunlu PETG White and Sunlu PETG Black are 1 kg spools you can dry using exactly the routine above.

TPU, ABS, nylon and the rest

For materials beyond PLA and PETG, the principle holds: go as high as the material allows without softening, and be patient.

TPU is flexible and soaks up water. It usually takes a longer, gentler session than PETG. Because it is soft already, overheating is a real risk, so do not push it. If you print flexible parts, our piece on why 95A hardness is the usual first TPU is a useful companion.

ABS and ASA absorb less moisture than other materials, but they still benefit from a dry-out when stored badly. They tolerate higher temperatures, which is why many people dry them alongside PETG settings or slightly above.

Nylon is the thirstiest of the lot. It can need the highest temperature and the longest time. A basic dryer capped at a modest temperature will do the job slowly, if at all. Check what your dryer can reach before you buy a nylon spool.

Whatever the material, apply one rule: when a manufacturer’s label and a forum post disagree, believe the label.

How to tell filament is wet

Do not dry every spool on a schedule. Dry the ones that show symptoms, and the ones that have been exposed for a long time.

Signs of moisture:

• Hissing or popping from the nozzle while extruding.
• Stringing and blobbing that retraction tuning does not cure.
• A rough, fuzzy or matt surface where it should be glossy.
• Weak, brittle parts or layers that do not bond well.
• Steam or bubbles visible at the nozzle tip.

None of these proves moisture alone. A worn nozzle or a too-hot setting can produce stringing too. The clean test: dry the spool and reprint the same file. If the problem disappears, you had your answer.

How to tell it is done

Time and temperature are the plan, but the evidence is what ends the session. Extrude a short length by hand or through the printer. If it is silent, smooth and glossy, stop. If you still hear crackling, run another 2 hours. Where your dryer has a humidity display, the iDryer figure of under 15% inside the chamber is a sensible target for PETG.

Setting a filament dryer

A dedicated dryer is easier than an oven. An oven’s thermostat can swing by many degrees, and overshoot is exactly what ruins PLA.

1. Choose the material preset or enter a temperature. Use the figures in the table, nothing higher.
2. Set the time conservatively. You can always extend.
3. Leave the lid vent as the manual directs. Moisture has to escape.
4. Keep it away from draughts and cold surfaces. A cold room lengthens the job.
5. Dry one spool at a time unless the dryer is designed for more, otherwise the centre of each reel stays damp.
6. Seal immediately. A spool starts picking moisture back up as soon as it leaves the dryer.

If you are choosing a unit, our SUNLU Filament Dryer S2 is a dedicated dryer in our 3D range. Check the product page for its current specification and match its temperature range to the materials you print.

Keeping filament dry afterwards

Drying is only half the job. A spool that goes straight back on a shelf in a damp room will be wet again within weeks. UK and Irish homes and workshops are generally humid for much of the year, so the habit matters more than it would in a dry climate.

• Store spools in airtight bags or boxes with desiccant.
• Add a small humidity gauge to the box and watch it.
• Print moisture-sensitive materials from a dry box or directly from the dryer.
• Do not leave a half-used reel on the printer for weeks.

We go into target humidity, sealing and monitoring in more detail in our filament moisture control guide. If you are newer to printing altogether, our guide to 3D filament printing covers choosing a material and setting up before you reach the drying stage.

Our view on drying

We supply 3D filament to trade customers, and the pattern we hear about is consistent: most print failures blamed on a bad batch turn out to be a damp spool. People change nozzle, slicer profile and supplier before they try four hours in a dryer.

Our advice is plain.

• Use the lowest temperature that works, for longer. Heat is how spools get ruined; time is free.
• Treat PLA and PETG as two different jobs. The gap between a safe PLA setting and a safe PETG setting is only about 10–15°C, and a dryer left on the wrong preset is the commonest mistake.
• Dry before you diagnose. If a spool has been open for a while, dry it before you tune retraction.
• Buy what you will use. Because we have no minimum order quantity, you can order a few spools at a time instead of stocking a year’s worth that sits and absorbs water. For a small workshop, that is often the cheapest drying strategy there is.

None of this needs expensive kit. A thermometer you trust, a sealed box and some patience cover most of it.

— chris

Stock your print shelf

If you run a print shop, workshop or maker business, our 3D supplies range covers filament and related supplies for trade customers, with no minimum order quantity. That means you can order the spools a job needs, dry them and use them, without buying surplus stock that will go damp on the shelf.

FAQ

What temperature should I dry PLA at?

Use 45–55°C, with 50°C a common choice. Keep it well below PLA’s glass transition range of roughly 58–65°C, or the spool can soften and fuse. Dry for about 4–6 hours and check the result.

What is the right PETG drying temperature?

The iDryer guidance is 65°C for a minimum of 4 hours, aiming for under 15% humidity inside the dryer. Heavily saturated spools can need up to twice as long. Finish by testing a short extrusion for popping.

How long should I dry filament for?

Four to six hours covers most PLA and PETG spools that are only mildly damp. Very wet or long-exposed spools may need eight hours or more. Stop when extrusion is quiet and the surface is smooth, not simply when a timer ends.

Can I dry filament in a kitchen oven?

It is possible, but we do not recommend it. Domestic oven thermostats swing widely, and an overshoot of only a few degrees can warp PLA. A dedicated dryer holds a steady low temperature and is safer for your spool and your kitchen.

Is a higher temperature faster?

Only up to the safe limit for the material. Past that, the spool deforms before it dries. Stay under the glass transition for PLA and extend the time instead.

Sources

• How to Dry PETG Filament, Dryer Settings and Presets (iDryer Portal)
• Impact of the FDM Printing Process on PLA Chemistry and Structure (Stony Brook University)
• Moisture experiment research, Fan et al. 2009 (Lamar University)
• Ageing performance of biodegradable PLA for durable applications (RIT thesis)
• Shini Plastics Technologies, PLA drying

Recommended

• Guide to 3D filament printing: choose, set up, print
• Silk PLA Finish for 3D Prints: Calibrate 205–215°C, Dry 4–6 Hours
• 3D printing materials list: FDM, resin and SLS guide
• Dry, Seal, Monitor: Filament Moisture Control at 10–20% RH for Makers