Nylon is notoriously hygroscopic, absorbing moisture from the air like a sponge. This moisture causes printing defects ranging from poor surface finish to complete print failure. In this comprehensive guide, you’ll learn how to properly dry, store, and maintain your nylon filaments.
Why Nylon Absorbs Moisture
Nylon’s chemical structure contains amide groups that form hydrogen bonds with water molecules. This hydrophilic nature means nylon will absorb moisture until it reaches equilibrium with ambient humidity.
At 50% relative humidity, nylon can absorb:
- PA6: 2.5-3% moisture by weight
- PA66: 2.0-2.5% moisture by weight
- PA12: 1.0-1.5% moisture by weight
PA12’s lower absorption rate makes it preferable for humid environments.
Signs of Moisture Contamination
Visual Indicators
- Popping sounds during extrusion (steam bubbles)
- White residue or “blooming” on print surface
- Bubbles in extruded filament
- Encordoamento and oozing
Print Quality Issues
- Poor layer adhesion
- Rough, bumpy surface texture
- Reduced mechanical strength (up to 50% loss)
- Dimensional inaccuracy
Drying Methods Compared
Food Dehydrator
The most accessible option for most users:
| Temperature | Duration | Suitability |
|---|---|---|
| 70°C | 6-8 hours | PA6, PA66 |
| 60°C | 8-12 hours | PA12, sensitive |
| 80°C | 4-6 hours | Moisture-heavy |
Pros: Inexpensive, effective, widely available
Cons: Limited capacity, manual monitoring
Dedicated Filament Dryer
Purpose-built solutions with precise control:
- Temperature control: 40-80°C
- Built-in humidity monitoring
- Spool rotation capability
- Direct feed to printer
Oven Drying
Use with caution:
1. Preheat to 70°C (never above 80°C for nylon)
2. Place spool on rack (not direct metal)
3. Prop door slightly open for moisture escape
4. Dry for 4-6 hours
5. Allow complete cooling before handling
Warning: Many ovens have temperature variance. Verify with thermometer.
Proper drying is essential before temperature calibration.
Optimal Storage Solutions
Vacuum Sealing
Most effective long-term storage:
1. Use vacuum bags designed for food storage
2. Add desiccant packets (silica gel)
3. Seal immediately after drying
4. Label with date and material type
Dry Box Systems
Active humidity control for frequent users:
- Passive: Airtight container with desiccant
- Active: Heated box with humidity control
- Hybrid: Combination with direct feed
Desiccant Types
| Type | Capacity | Reusable | Cost |
|---|---|---|---|
| Silica Gel | Good | Yes | Baixa |
| Molecular Sieve | Excelente | Yes | Medium |
| Indicating (blue) | Good | Yes | Baixa |
Prevention Best Practices
Handling Rules
1. Never leave filament exposed to air
2. Return to storage immediately after printing
3. Use dry boxes for humid climates
4. Monitor humidity with hygrometer
Environmental Control
- Print room humidity: Below 40% RH ideal
- Avoid printing during rain/humid days
- Air conditioning helps reduce humidity
- Consider dehumidifier for workshop
Testing for Moisture
The Simple Test
Heat your nozzle to printing temperature and extrude filament:
- Dry nylon: Smooth, glossy extrusion
- Wet nylon: Hissing, popping, bubbles, rough surface
Weight Measurement
For precise determination:
1. Weigh spool before drying
2. Dry completely
3. Weigh again
4. Calculate moisture percentage
Target moisture: Below 0.2% for optimal printing
Frequently Asked Questions
How long can nylon sit out before it’s too wet?
In 50% humidity, nylon becomes too wet in 24-48 hours.
Can I overdry nylon?
Yes, excessive heat or time can cause degradation. Stay below 80°C.
How do I know when desiccant needs recharging?
Indicating desiccant turns pink/orange when saturated.
Frequently Asked Questions
Why is my print quality inconsistent?
Multiple factors affect quality: temperature stability, filament quality, and machine calibration. Test systematically.
How can I improve my print success rate?
Start with proper calibration, quality filament, and appropriate settings for each material.
What maintenance does my printer need?
Regular nozzle cleaning, belt tensioning, and lubrication of moving parts.
Frequently Asked Questions
Q: How much moisture does Nylon absorb from the air?
Nylon can absorb 5-9% of its own weight in moisture depending on relative humidity and temperature. At 50% RH, Nylon reaches equilibrium at approximately 2-3% moisture content. At 80% RH, it can absorb 5-6%. This absorbed moisture significantly lowers the glass transition temperature and affects print quality.
Q: What happens when you print wet Nylon filament?
Wet Nylon produces steam bubbles and hissing sounds at the nozzle during extrusion. This causes: poor surface finish (popping and bubbles), stringing and oozing, weak layer bonds leading to delamination, dimensional inaccuracies, and in severe cases complete print failure.
Q: What is the correct drying temperature and time for Nylon?
Dry Nylon at 80 deg C for 6-8 hours using a convection oven or dedicated filament dryer. For large spools or high-humidity environments, extend to 10-12 hours. Avoid temperatures above 90 deg C as the spool may deform. Print directly from the dryer if possible, or store in an airtight container with desiccant.
Q: How should Nylon filament be stored after drying?
Store dried Nylon immediately in an airtight container with desiccant packets (silica gel or Drierite). For best long-term storage, use vacuum bags with desiccant. Even in a sealed container, Nylon will reabsorb moisture – re-dry filament that has been stored open for more than 2-4 hours.
Q: What are the signs that Nylon needs re-drying?
Listen for popping and hissing sounds during extrusion – this is the most obvious sign of moisture. Inspect the extruded filament for bubbling, inconsistent diameter, or steam rising from the nozzle. A moisture indicator card inside the storage container shows when re-drying is needed.
Q: Can a standard food dehydrator be used to dry Nylon?
Yes, but with caution. Use a food dehydrator that can maintain a stable 80 deg C. Avoid dehydrators with temperatures exceeding 100 deg C. Place the filament spool in a mesh basket to allow airflow around it. However, a dedicated filament dryer with sealed chamber and desiccant is a better investment.
Q: Does desiccant need to be regenerated, and how?
Silica gel desiccant turns from blue to pink when saturated with moisture. To regenerate: bake at 120 deg C for 2-4 hours until it returns to blue. Replace desiccant that has been used extensively or is no longer regenerating properly.
Q: How does Nylon moisture affect mechanical properties?
Moisture acts as a plasticiser in Nylon, actually making it more flexible but significantly weaker when printed. Print quality (surface finish, dimensional accuracy) is compromised far more than mechanical strength for functional parts.
Q: What humidity conditions require extra Nylon drying care?
High humidity areas (RH > 60%) require daily drying of Nylon. Coastal, tropical, and rainy-season environments are particularly problematic. In areas with RH above 70%, consider storing Nylon in a dry box permanently connected to your printer.
Q: Can you print Nylon directly from a dry box on the printer?
Yes, this is the best practice for consistent Nylon printing. Load the spool into a sealed dry box mounted on top of or beside your printer, with a small hole for the filament path. This eliminates the re-absorption problem between prints and ensures consistent quality across long print jobs.
