How to Dry PLA Filament: 5 Easy Fixes For Wet Plastic

PLA, or polylactic acid, is one of the most common beginner filaments for 3D printers due to its low warping, limited fumes, and overall ease of use. However, PLA has a hygroscopic nature, meaning it readily absorbs moisture from the ambient environment. This can lead to quite a few issues when it comes time to 3D print.

In this guide, we’ll cover the problems that arise when using wet PLA filament and detail 5 simple methods for properly drying it before use. 

I. Problems of Wet PLA Filament

PLA filament left exposed to humidity or direct contact with water over time will absorb a considerable amount of moisture from the air. After that, you’ll immediately notice poor extrusion from the nozzle when using wet filament. Prints will have weak layer adhesion and pronounced flaws in tolerances, dimensions, and appearance.

Wet PLA can also cause complete jams and clogs in your extruder. The built up moisture literally boils and pops from the heat of the hot end. As steam expands rapidly, it prevents the filament from properly feeding through the extruder mechanism.

Wet filament can cause stringing in 3D prints (Photo: Ultimaker)

II. Five Effective Ways to Dry PLA Filament

Method 1: Oven Drying

One of the most effective DIY methods for drying PLA filament is using your kitchen oven:

• Pre-heat your oven to the lowest temperature setting, ideally around 150°F to 180°F max. Going over 200°F risks deforming the plastic.
• Place your filament spool on an oven safe metal tray or pan. This prevents direct contact and overheating from the oven rack.
• Leave the oven door slightly cracked open. This allows moisture to escape as it releases from the filament.
• Dry for 2 to 6 hours. Begin checking the filament every 30 minutes once you’re past the first 2 hours.

Method 2: Silica Gel

Silica gel is a desiccant that readily absorbs moisture from the surrounding environment. 

To dry filament with silica gel:

• Obtain a large airtight storage bin, Tupperware container, or resealable plastic bag.
• Place loose silica gel beads or packets into the container along with your filament spool. One option is to hang the spool on a dowel inside the container so air can circulate underneath.
• Seal the container completely. Allow 1 to 2 days for the silica gel to fully absorb moisture from the filament. 
• Use a dedicated hygrometer to monitor the internal humidity and determine when drying is complete. The container should reach very low internal humidity.

Silica gel (photo: GoodHousekeeping)

Method 3: Filament Dryer

Filament dryers are appliances designed specifically for drying 3D printing filament via heating and circulating air.

Key features when selecting a filament dryer:

• Temperature control based on plastic type - PLA generally 110°F to 140°F（43°C - 60°C）
• Timer function for setting drying duration
• Sealed chamber with active airflow
• Spool holder and spindle to allow unwinding
• Moisture monitoring
• Large enough for 1kg or 2kg spools

Simply load your filament, set the target temperature and time, then walk away until drying is complete. The active heating and air circulation accelerates removing moisture very quickly. Just be sure not to overheat past the optimal level.

SUNLU S2 3D Printing Filament Dryer Box

Method 4: Food Dehydrator

A food dehydrator can be an effective way to dry out moist PLA filament and revitalize the material for better 3D printing performance.

• Constant warm airflow and circulation in a dehydrator gradually dries filament
• Loosely spool filament and place in dehydrator trays
• Set temperature to 45-60°C and dehydrate for 4-6 hours
• Turn and reposition filament midway for even drying
• Affordable at-home technique without an industrial dryer

Food Dehydrator (photo: Salton)

Method 5: Refrigerant Drying

Refrigerant crystals like DampRid work by absorbing moisture through hygroscopic action. The crystals pull water vapor directly from the air and surfaces in an enclosed space.

• Obtain a plastic tub with an airtight lid or other sealable container.
• Place the filament spools inside the tub. For faster drying, remove filament from the spools and loosely spread it out.
• Add the refrigerant crystals into the tub, using around 100-200g per 1kg of filament. Spread the crystals around.
• Seal the tub tightly and leave for 6-12 hours. The crystals will actively absorb moisture from the filament.
• Check on the refrigerant after 6 hours. If the crystals have turned liquid, they have fully absorbed moisture. Replace with new crystals.
• Recharge used crystals by drying in an oven at a low 150°F for 1-2 hours. The moisture will evaporate, reviving the crystals.

III. Storing PLA Filament Correctly

Proper storage is just as crucial as drying your filament in the first place. Leftover moisture in your filament will lead to gradual re-absorption from the ambient humidity. Follow these guidelines when storing PLA filament:

• Use airtight plastic containers or resealable bags. Make sure any seals are fully closed.
• Include several desiccant packets in the container to maintain very low humidity levels. Replace packets periodically.
• Vacuum sealing bags provides excellent protection by fully removing internal air and moisture.
• Store filament in cool, dry areas away from direct sunlight and heat sources.

10Pcs Filament Storage Vacuum Bag

IV. Conclusion

Wet PLA filament can be incredibly frustrating to work with, but is easily fixed through proper drying and storage methods. Simply oven drying provides a quick DIY solution, while dedicated dryers offer set-it-and-forget-it performance for frequent use.

Following the recommendations in this guide will help you achieve consistent, flawless print results with PLA filament. Take control of moisture and you’ll be primed for 3D printing success.

FAQS:

Q1: What problems can wet PLA filament cause in 3D printing?

A1: Wet PLA can cause poor extrusion, weak layer adhesion, print defects, and complete jams/clogs in the extruder. The moisture boils and pops from the hot end heat.

Q2: How do I dry my PLA filament?

A2: Effective ways to dry PLA include oven drying, silica gel, a filament dryer, food dehydrator, or refrigerant crystals. Follow specific guidelines for each method.

Q3: How long does it take for PLA to dry?

A3: Oven drying takes 2-6 hours. Silica gel absorbs moisture over 1-2 days. A filament dryer dries more quickly.

Q4: Can you use a hair dryer to dry PLA filament?

A4: It's not recommended. A hair dryer may not evenly dry filament or regulate temperature properly. Use oven or dehydrator instead.

Q5: Does moisture make PLA brittle? Can you remove moisture from filament?

A5: Yes, moisture makes PLA brittle over time. Proper drying effectively removes moisture from wet filament.

Q6: What are the benefits of using a filament dryer?

A6: A filament dryer offers regulated temperature control, active airflow, and easy spool loading. It dries filament quickly with no monitoring needed.

Q7: Is a filament dryer worth it? Does PLA need a filament dryer?

A7: A filament dryer can be a worthwhile investment for those printing frequently with PLA or other materials prone to moisture absorption. It saves time and effort over other methods.

See Also

Why a Heated Filament Dryer is a Must-Have for 3D Printing

Can 3D Printer Filament Go Bad? - Essential Facts

5 Best Ways for 3D Printer Filament Storage