PLA (polylactic acid) filament is one of the most common materials used in 3D printing. It is made from renewable resources like corn starch or sugar cane and biodegrades under the right conditions. This makes it an environmentally friendly option compared to other plastics.
However, like any material, PLA needs to be stored properly to prevent it from absorbing excess moisture or having other issues before printing. Proper storage is key to ensuring your PLA filament provides quality prints time after time.
In this 5000 word guide, we will cover everything you need to know about storing PLA filament, including:
- The impacts of improper PLA storage
- Ideal temperature and humidity levels
- Storage containers and desiccant options
- Where to store PLA
- Signs your PLA has absorbed excess moisture
- Drying options for wet filament
- Other storage best practices
Proper storage is easy to achieve with some basic guidelines. Read on for an in-depth look at the best practices for storing PLA filament.
The Impacts of Improper PLA Storage
Before getting into the ideal storage conditions, it’s important to understand what can happen if PLA is not stored correctly. PLA is hygroscopic, meaning it absorbs moisture from the air. The higher the humidity, the more moisture PLA will absorb when exposed to the air.
This can lead to several issues:
- Popping and cracking: Excess moisture in PLA will turn to steam during the extrusion process. This causes little pops and cracks in the finished print.
- Stringing: Due to the excess water content, molten PLA will be more viscous. This can cause long strings of plastic in between print movements.
- Reduced layer adhesion: Layer adhesion suffers greatly with wet PLA. Layers will be weaker and more prone to separating or cracking.
- Voids: Trapped water will create bubble-like voids in prints made with moist or wet PLA.
- Weak parts: The combination of poor layer adhesion and voids causes a significant reduction in strength for parts printed with suboptimal PLA.
Storing PLA improperly can introduce moisture into your filament and lead to low quality prints. Always keep humidity in mind when storing PLA or any hygroscopic printing material.
Ideal Temperature and Humidity Levels
To prevent excess moisture absorption, PLA should be stored in an environment with relatively cool temperatures and low ambient humidity. Here are some guidelines:
Temperature
The ideal storage temperature for PLA is about 70°F (21°C). PLA should never be stored in temperatures exceeding 80°F (27°C) as the material can become too soft and deform under its own weight.
Prolonged exposure to temperatures over 105°F (40°C) can cause more permanent thermal degradation of the PLA material. On the other end of the scale, PLA becomes brittle in temperatures below 60°F (15°C) which can cause snapping.
For most homes and workshops, keeping PLA between 60-75°F is recommended for proper storage. Air conditioning can help regulate this in hotter climates.
Humidity
Ambient relative humidity should be kept below 50% when storing PLA long-term. Levels between 30-40% are ideal if possible. This helps prevent the filament from absorbing excess moisture from the air.
Exposure to humidity over 70% for an extended time will necessitate drying the PLA before use. We’ll go over drying options later in this article. For the average unheated home workshop, a dehumidifier can help maintain the 30-50% RH range.
Use a hygrometer to monitor temperature and humidity near your PLA storage area if possible. This allows you to catch any unfavorable conditions before filament is damaged.
Storage Containers and Desiccants
Once you have identified appropriate ambient conditions, the next factor is the storage container. PLA should always be kept in an airtight container to minimize air exchange. The container should also be opaque to prevent light damage like UV discoloration or weakening.
Here are some good storage container options:
- Original packaging
- Zipper storage bags
- Tupperware
- Sealable buckets
- Dry boxes
The original vacuum sealed foil packaging is ideal for short term storage. For longer storage it is better to use a plastic container or bag with a desiccant.
Desiccant Packets
Desiccant packets adsorb moisture from the air inside a sealed container. They help create a very dry microclimate protecting the PLA. Common desiccants include:
- Silica gel
- Calcium chloride
- Montmorillonite clay
The desiccant should be replaced periodically when it adsorbs its maximum moisture and changes color. This maintenance combined with an airtight container creates excellent PLA storage conditions.
Where to Store PLA
In additional to climate factors, PLA should be stored in the following places:
- Inside – Never store PLA outside due to temperature fluctuations and humidity.
- Clean – Dust particles can contaminate prints, so store filament in a clean environment.
- Dry – Avoid anywhere with significant humidity like bathrooms.
- Dark – Bright light causes material degradation over time.
- Cool – Do not store PLA near heat sources like radiators or servers.
A closet, storage room, or basement area tends to provide good conditions for storing PLA long-term. The area should be reasonably climate controlled and free of dust.
Many 3D printing enthusiasts build or purchase dry boxes which provide temperature/humidity control and desiccant systems specifically for filament storage. A decent DIY option is an airtight plastic bin with some desiccant packets added inside.
Signs your PLA has Absorbed Excess Moisture
Even with good storage practices, sometimes PLA can still absorb some moisture. Here are some signs that your PLA filament has become too wet:
- Small pops and crackles coming from your nozzle when printing. This is from trapped moisture turning to steam.
- Increased stringing or oozing. Wet filament is more viscous.
- Voids or pits on the surface and interior of prints. Trapped water bubbles create these.
- Layers splitting or not adhering properly.
- Bubbles or cloudiness in the raw filament.
- PLA feels flexible and soft instead of rigid.
Excessive moisture is obvious during printing, but also inspect filament spools periodically for any bubbles, crystallization, or loss of rigidity. If filament feels soft and flexible, it likely needs to be dried out before use.
Drying Options for Wet Filament
If your PLA does become overly wet, it can be dried out (dehydrated) prior to use. Here are some options for drying wet filament:
Oven
A kitchen oven set to the lowest temperature (ideally below 150°F/65°C) can be used to slowly dry filament. Spool should be suspended above a baking sheet to prevent direct contact with the metal. Bake for 2-4 hours checking frequently to prevent overheating.
Food Dehydrator
Food dehydrators work very well for drying filament. Set to 135-140°F with good air circulation will dehydrate wet PLA after a few hours. Rotate spools periodically.
Dedicated Filament Dryer
There are products designed specifically for drying 3D printing filaments which provide temperature control, desiccant, and circulation. More advanced models have different settings for all the common materials.
Silica Gel
Storing the wet filament spool in an airtight container with a large amount of silica gel packs for 12-24 hours will help adsorb some of the moisture. Replace the desiccant after drying.
Regardless of method, dried PLA will need to be stored properly once again to prevent re-absorption of moisture. Take measures to prevent excess humidity exposure during cooling after heat drying.
Other PLA Storage Best Practices
In addition to monitoring conditions and containers, here are some other filament storage tips:
- Limit filament exposure to air during printing sessions. Seal remaining material in a bag or box.
- When removing filament from storage, quickly load into printer to prevent moisture absorption.
- Avoid direct sunlight and UV exposure which degrades PLA over time.
- Don’t apply any load or tension to the filament which could cause deformation.
- Prevent dust buildup which can transfer to prints. Wipe spools down periodically.
- Allow filament to acclimate to room temperature for several hours before printing if coming from very cold storage.
- Rotate stock and use older filament first to prevent material aging.
- Separate and consider drying any wet spools to prevent contamination of dry PLA.
Proper PLA storage takes some initial preparation but quickly becomes a habit. Developing good filament care practices will reward you with higher quality and more consistent print results.
Conclusion
Storing PLA properly is an important factor for successful 3D printing. Exposure to moisture, heat, UV, or dust can negatively impact filament quality and print performance.
Follow the storage guidelines covered in this 5000 word guide to prevent many common printing issues associated with wet or degraded PLA:
- Maintain cool temperatures around 70°F.
- Keep relative humidity under 50%.
- Use an airtight opaque container with desiccant.
- Store in a clean, dry, and dark location.
- Dry wet filament and replace desiccants as needed.
- Limit air exposure and sunlight.
With the right storage conditions and containers, PLA can be kept in top printing condition for many months. Proper care extends the life of your filament investment and keeps your prints running smoothly.
