Drying 3D Printing Materials: Why It Is Essential for Quality Results

Drying 3D printing materials is one of the most important steps when aiming for a stable process, a clean surface finish, and predictable mechanical properties. Even well-tuned print parameters cannot always compensate for the effects of moisture, which is why material condition often has a bigger impact than it may seem at first glance. In this article, we explain why drying is not just an optional extra, but a normal part of process control.

Why drying is not just an optional extra?

The effect of moisture on 3D printing materials is one of the most important, yet still too often underestimated, factors in the process. Many thermoplastics used in 3D printing are hygroscopic, which means they absorb moisture from the surrounding air even when they are not actively being used. During printing, this moisture turns into steam, directly affecting material flow, layer structure, and the final mechanical properties of the part. For this reason, drying should not be treated as an additional precautionary step — it is an integral part of a stable, repeatable, and predictable printing process.

What is hygroscopicity and why does it matter in 3D printing?

Hygroscopicity is a material’s ability to absorb moisture from the surrounding air. Many thermoplastics used in 3D printing have polymer chains that allow water molecules to penetrate the material structure. What makes this especially important is that the absorbed moisture is often not visible to the naked eye — a spool may look perfectly fine, while already containing enough water to cause surface defects, unstable extrusion, or reduced mechanical performance during printing. The longer the material is stored in open air and the higher the relative humidity, the greater the risk that its condition will change before printing even begins.

What happens to moist material during printing?

During printing, the material enters the hot zone, where temperatures often reach 200–300 °C or more. Under these conditions, the absorbed moisture instantly turns into steam. Because the volume of steam is several hundred times greater than that of water, the moisture begins to disrupt consistent material feeding and interferes with stable layer formation. In practice, this usually appears as uneven extrusion, microbubbles within the layers, poorer layer adhesion, and a lower-quality surface finish. In some materials, moisture does not only affect visual appearance, but also the internal structure of the printed part, making the problem more than cosmetic and directly related to final part reliability.

How to recognize in practice that a material has absorbed moisture

The effects of moisture usually do not appear as a single symptom, but as several symptoms at the same time. In practice, the following signs are most commonly observed:

• increased stringing between features;
• an uneven or “fuzzy” surface;
• visible bubbles within the layers;
• brittle parts that break where they should not;
• unstable extrusion even when using a previously reliable print profile.

If the same print profile used to work consistently and the result has now deteriorated, it is very likely that the problem lies not in the settings, but in the material itself.

Is a new material straight out of the package always dry?

The short answer is no. Although most materials are supplied in vacuum packaging with desiccant, that does not guarantee an ideal dry state. The material may have:

• been stored in a warehouse for a long time;
• been packaged with residual moisture already present;
• experienced temperature and humidity fluctuations during transport.

For this reason, in professional environments a new spool is often dried preventively before the very first print. This is not excessive caution — it is process control and a way to reduce unnecessary risk from the start.

Which materials require drying the most?

Although drying is beneficial for almost all materials, there is a group for which it becomes practically mandatory. PA (nylon) family materials absorb moisture very quickly and often print unstably without drying. Composite materials filled with carbon or glass fiber tend to make the effects of moisture even more apparent. TPU is also highly sensitive to moisture, especially during longer print jobs. PETG shows medium sensitivity, but when stored in open air it quickly loses surface quality. PLA is often considered more resistant, but even here moisture can negatively affect longer, more precise, or visually demanding prints.

Material	Hygroscopicity	Drying temperature	Drying time	Notes
PLA	Low–medium	45–50 °C	4–8 h	Often considered more resistant, but drying is recommended for longer or more precise prints.
PETG	Medium	55–65 °C	6–8 h	Quickly loses surface quality and increases stringing when stored in open air.
ABS	Low	60–65 °C	2–4 h	Rarely critical, but beneficial before larger or technical prints.
ASA	Low	70–80 °C	4–8 h	More moisture-sensitive than often assumed; worth drying before technical jobs.
TPU	High	60–70 °C	4–8 h	Very sensitive to moisture; unstable extrusion and surface defects appear quickly.
PA6 / PA12	Very high	70–80 °C	6–12 h	Without drying, stable printing often becomes impossible, especially after longer storage.
PA6-GF	Very high	70–80 °C	8–12 h	Fillers make moisture effects and print instability even more visible.
PA6-CF	Very high	70–80 °C	8–12 h	Fillers make moisture effects and print instability even more visible.
PC	High	80–90 °C	5–8 h	Moisture directly reduces mechanical properties and layer quality.
PPS	Medium–high	80–90 °C	4–6 h	Requires a stable, controlled drying and storage environment.
PPS-TF	High	80–90 °C	6–8 h	Industrial material; drying is often treated as a normal process stage.
PPS-CF	High	90–100 °C	8–10 h	Composite PPS version; exact drying conditions should be checked against the manufacturer’s TDS.
PEEK	Medium–high	120–150 °C	4–6 h	High-temperature material; moisture has a critical effect on mechanical properties.
PEKK	Medium–high	120–150 °C	4–6 h	Similar behavior to PEEK; sensitive to storage conditions.
PEI (ULTEM)	Medium	120–150 °C	4–6 h	High-temperature material that requires a consistent drying routine.
PSU	Medium	100–120 °C	4–8 h	Used in technical applications; moisture affects surface quality.
PVDF	Low	80–100 °C	3–5 h	Drying requirements depend on the specific manufacturer and formulation.
POM	Low	60–80 °C	2–4 h	Often considered less sensitive, but recommendations strongly depend on the manufacturer.
PMMA	Low–medium	60–80 °C	2–4 h	Moisture most often shows up through surface quality and optical clarity.

Important note. The drying temperatures and drying times listed above are approximate guidelines. Actual conditions may vary depending on the specific material formulation, fillers, manufacturer recommendations, and storage history. In practice, it is always best to refer to the technical data sheet (TDS) of the specific material first, and only then adjust the process according to actual results.

Drying before printing and during printing

There are two main approaches to drying, and both have their place in practice.

Drying before printing is suitable for shorter or one-off jobs, where the goal is to quickly restore the material to a proper condition. However, during longer print jobs the material may start absorbing moisture from the surrounding air again, especially when printing in an open environment. For that reason, initial drying alone does not always guarantee a stable result throughout the entire process.

Drying during printing is especially important when hygroscopic 3D printing materials are being used and the print job takes longer. This is why the method is most often used in production environments, for longer print jobs, and whenever not only visual quality but also mechanical properties matter.

In 3D printing, drying is still often treated as an additional step, but in reality it is a basic part of process control. Just like mechanical calibration or temperature control, material condition directly affects the final result. Dry material allows the process to take full advantage of the material’s real properties without workarounds or unnecessary profile corrections.

How to store material after drying?

Even properly dried 3D printing materials may fail to deliver the expected result if, after the drying process, they are left in an open environment. That is why drying alone is not enough — storage conditions must also be controlled before and during printing.

In practice, the best results are achieved when dried 3D printing materials are stored in a sealed box with desiccant or fed directly from a controlled drying system. The more hygroscopic the material, the shorter its “safe time” in open air. This is especially relevant for PA, TPU, PC, and composite materials.

If a spool sits in the workshop for several hours or longer after drying, its real condition may already differ from the condition it had immediately after the process. This is why, in professional environments, it is important to control not only drying itself but the entire material storage chain.

The most common mistakes in drying 3D printing materials

One of the most common mistakes is assuming that a new sealed package automatically means dry material. Another common mistake is drying “by feel,” without relying on the material type or the manufacturer’s recommendations. It also happens that a material is dried properly, but then left in open air and absorbs moisture again before printing.

It is equally important to avoid overly aggressive drying. Excessively high temperature or excessive drying time can affect the geometry, surface, or general stability of certain materials. For this reason, 3D printing material drying should be viewed not as a household routine, but as a controlled technological step.

Conclusion

Drying 3D printing materials is not a random extra step or an unnecessary precaution. It is a direct part of process control that affects not only surface finish, but also layer adhesion, dimensional stability, and the final mechanical properties of the part.

The more technical the material and the higher the requirements for the printed part, the less room there is for guesswork. In practice, it is far more reliable to control moisture in advance than to try to compensate for its effects later through profile adjustments. Dry material allows the process to work consistently, repeatably, and predictably — and that is exactly what is needed when aiming for high-quality results.

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Drying 3D Printing Materials

2026 March 30

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