When it comes to reliable 3D printing, PETG filament stands out for its balance of strength, flexibility, and ease of use. However, many makers and hobbyists encounter a frustrating problem: moisture absorption. Storing PETG filament properly is critical, as even a small amount of humidity can degrade its quality and ruin print results. In this guide, you’ll learn why PETG is sensitive to moisture, how to identify affected filament, and, most importantly, how to store your PETG filament to keep every spool fresh and ready for perfect prints.
Understanding PETG and Moisture Absorption
PETG (Polyethylene Terephthalate Glycol) is a popular choice for 3D printing due to its excellent mechanical properties and user-friendly nature. Yet, like many thermoplastics, PETG is hygroscopic, meaning it absorbs moisture from the air. Even in environments that feel dry to us, airborne humidity can gradually make its way into the filament.
You may wonder why this matters. When PETG absorbs moisture, that water turns to steam inside your printer’s hot end, causing visible bubbles, stringing, and rough surfaces on your printed objects. Recognizing these issues early can save you a lot of time and material. Common signs of moisture-laden PETG include popping sounds during printing, fuzzy or brittle prints, and an overall decrease in print quality.
The Impact of Moisture on PETG Filament
Moisture can seriously compromise the performance of PETG filament. When the water molecules trapped inside the filament hit high temperatures during printing, they vaporize and expand rapidly. This process creates air pockets or bubbles in the extruded plastic, leading to prints with a rough texture, inconsistent layering, and even reduced strength. Additionally, excessive stringing or oozing can result, leaving you with parts that require extensive post-processing or are simply unusable.
In the long run, moisture can cause the filament to become brittle, making it prone to snapping both during printing and handling. If you value your print quality, learning how to keep PETG dry should be a top priority.
Best Practices for Storing PETG Filament
The number one rule for storing PETG filament is simple: keep it dry. To achieve this, you’ll need to control both humidity and temperature. Ideally, store your filament in a cool, dry location, away from direct sunlight or heat sources. The goal is to maintain a relative humidity below 20% in the storage environment.
Whenever possible, store filament spools in their original packaging with silica gel or another desiccant. If the packaging isn’t reusable, there are plenty of effective alternatives to consider.
Storage Solutions for PETG Filament
Vacuum-Sealed Bags and Containers:
Vacuum-sealed storage bags are one of the most effective ways to protect PETG filament from moisture. These bags remove air and seal tightly, preventing humidity from entering. Add a silica gel packet inside for extra insurance.
Airtight Plastic Bins:
Large plastic bins with airtight lids are great for storing multiple spools. Place several desiccant packs or reusable silica gel containers inside, and make sure the lid seals completely. This solution is affordable, scalable, and easy to access.
Filament Dry Boxes:
For the most serious makers, filament dry boxes (commercial or DIY) maintain precise temperature and humidity levels. Some models even allow you to print directly from inside the dry box, ensuring the filament never has a chance to absorb moisture.
Resealable Plastic Bags:
Heavy-duty resealable bags, such as freezer bags, can be used for individual spools. Just like with larger bins, always add a silica gel pack and push out as much air as possible before sealing.
Tips for Handling PETG Between Printing Sessions
Even if you print frequently, don’t leave PETG filament exposed to open air. Each time you finish a print session, promptly return the spool to its storage container or bag. Regularly check the color of silica gel packets—many change color when saturated—to ensure they’re still effective.
If you have multiple spools, label them with the date of opening and keep them organized so older stock is used first. This rotation reduces the risk of any spool sitting unused for long periods and absorbing moisture.
What to Do If Your PETG Absorbs Moisture
Don’t panic if your PETG filament has absorbed some moisture. It’s often possible to restore it with a little care. Use a dedicated filament dryer or a food dehydrator set to 50-60°C (122-140°F) for several hours. An oven can also work, but keep the temperature low and monitor it closely to avoid melting or deforming the spool.
After drying, test print a small object to check for improvements in quality. If popping sounds and stringing are gone, your filament is ready to use again.
Frequently Asked Questions
Can I store PETG with other filaments?
Yes, as long as all filaments are kept in low-humidity, airtight conditions with desiccant.
How often should I check on my stored filament?
Check monthly, especially if you’re in a humid climate or use desiccants that change color to indicate moisture.
What’s the best way to tell if my PETG needs drying?
If you notice popping noises, increased stringing, or rough surfaces on prints, your filament likely needs to be dried.
Conclusion
Storing PETG filament the right way doesn’t require expensive equipment—just a little vigilance and the right storage solutions. By keeping your spools dry and checking on them regularly, you’ll avoid moisture-related print failures and get consistently great results. For high-quality PETG filament and top-notch storage solutions, visit filalab.shop and give your 3D printing projects the foundation they deserve.