How to Fix Stringing and Oozing in 3D Prints

Stringing and oozing are two of the most frustrating problems in FDM 3D printing. You design a perfect model, wait hours for it to print, and pull it off the bed only to find it covered in thin wisps of plastic that look like spider webs. The good news? Stringing is almost always fixable with a few setting changes.

What Causes Stringing?

Stringing happens when small amounts of filament leak from the nozzle while the print head moves between different parts of your model. These “travel moves” should ideally happen without any material coming out. When filament oozes during travel, it creates thin strings between features.

The main culprits are:

• Retraction settings - The printer pulls filament back before travel moves. If retraction is too slow, too short, or disabled, filament keeps flowing.
• Temperature too high - Hotter filament is more liquid, making it harder to control. Even 5 degrees can make a big difference.
• Travel speed too slow - The longer the nozzle spends over empty space, the more time filament has to ooze out.
• Wet filament - Moisture in filament creates steam that pushes melted plastic out unpredictably.

Step 1: Tune Your Retraction Settings

Retraction is the single most important setting for eliminating stringing. When your slicer creates a travel move, retraction pulls the filament backward to create negative pressure in the nozzle, preventing ooze.

Key retraction settings:

• Retraction distance - How far the filament is pulled back. For Bowden setups (like the Ender 3), start at 5-7mm. For direct drive extruders (like the Bambu Lab P1S), start at 0.5-2mm.
• Retraction speed - How fast the filament is pulled back. Start at 25-45mm/s. Too fast can grind the filament; too slow won’t create enough negative pressure.
• Minimum travel distance - Only retract when the travel move is longer than this value. 1.5-2mm is a good starting point.

Quick test: Print a retraction tower (available on most slicer marketplaces). This test model varies retraction distance at different heights so you can see exactly which setting works best for your printer and filament combo.

Step 2: Lower Your Print Temperature

If retraction tuning alone doesn’t fix the problem, your nozzle temperature may be too high. More heat means more fluid filament, and fluid filament oozes more easily.

How to find the right temperature:

1. Print a temperature tower - a test model that changes nozzle temperature every few layers.
2. Start at the manufacturer’s recommended range. For PLA, that’s usually 190-220°C. For PETG, it’s 220-250°C.
3. Look for the section with the best combination of layer adhesion (no delamination) and minimal stringing.
4. A good rule of thumb: print at the lowest temperature that still gives you strong layer bonding.

Pro tip: Even within the same brand of filament, different colors can print better at slightly different temperatures. Black filament often prints well a few degrees cooler than white.

Step 3: Increase Travel Speed

The faster your print head moves during non-printing travel moves, the less time filament has to ooze. Most slicers default to 120-150mm/s for travel speed, but you can often push this to 200mm/s or higher without issues.

In Cura, look for “Travel Speed.” In PrusaSlicer and OrcaSlicer, it’s under “Speed > Travel.” Bambu Studio users can find it under the same speed section.

Just make sure your printer can handle the speed mechanically. If you hear your stepper motors skipping or your prints shift, dial it back.

Step 4: Enable Combing or Avoid Crossing Perimeters

Most slicers have a feature that keeps the nozzle inside the printed area during travel moves. In Cura, it’s called “Combing Mode.” In PrusaSlicer and OrcaSlicer, it’s “Avoid Crossing Perimeters.”

When enabled, the print head will take a longer path to stay within already-printed areas instead of crossing open gaps. This means even if some oozing occurs, it happens on top of existing material rather than creating visible strings in open space.

Set combing to “Within Infill” for the best results - any minor oozing will be hidden inside the print.

Step 5: Dry Your Filament

Wet filament is a silent stringing killer. Nylon and PETG absorb moisture from the air within hours. Even PLA can absorb enough moisture over weeks to cause problems.

Signs of wet filament:

• Popping or crackling sounds during printing
• Rough, bubbly surface finish
• Excessive stringing that doesn’t respond to retraction tuning
• Small blobs or zits on the surface

How to dry filament:

• Use a filament dryer (like the EIBOS Tetras or Sunlu S2) at the recommended temperature for your material
• In a pinch, use a food dehydrator or conventional oven at low temp (be careful with ovens - they can be inaccurate)
• PLA: 45°C for 4-6 hours
• PETG: 65°C for 4-6 hours
• Nylon: 70°C for 8-12 hours

Step 6: Use Z-Hop (With Caution)

Z-hop lifts the nozzle slightly during travel moves, creating a small gap between the nozzle tip and the print surface. This can reduce stringing by preventing the nozzle from dragging through existing material.

However, z-hop can sometimes make stringing worse because the nozzle has more time in the air to ooze. Use a small z-hop value (0.2-0.4mm) and test carefully.

Step 7: Clean Your Nozzle

A partially clogged nozzle can cause inconsistent extrusion and oozing. If you’ve tried all the settings above and still see stringing, try:

1. Cold pull - Heat the nozzle to printing temp, push filament through, let it cool to ~90°C (for PLA), then firmly pull the filament out. The cooled filament will pull debris with it.
2. Acupuncture needle - While the nozzle is hot, carefully insert a cleaning needle (usually included with your printer) to clear any blockage.
3. Replace the nozzle - Brass nozzles are cheap ($1-2 each). If you’ve been printing for months, a fresh nozzle can make a huge difference.

Quick Reference: Stringing Fix Checklist

Setting	Bowden (Ender 3)	Direct Drive (P1S, Prusa)
Retraction Distance	5-7mm	0.5-2mm
Retraction Speed	25-45mm/s	25-45mm/s
Nozzle Temp	Lowest that bonds	Lowest that bonds
Travel Speed	150-200mm/s	150-200mm/s
Combing	Within Infill	Within Infill

FAQ

Why does my PLA string more than my PETG? This isn’t typical - PLA usually strings less than PETG. If your PLA strings more, your temperature is likely too high or your filament has absorbed moisture. Try dropping temp by 5-10°C and drying the spool.

Do retraction settings change for different filaments? Yes. PETG generally needs less retraction than PLA on the same printer because it’s more viscous. TPU (flexible) should have very little or no retraction because it can buckle in the extruder. Always re-tune retraction when switching materials.

Will faster printing reduce stringing? Faster print speed (not just travel speed) can sometimes reduce stringing because the nozzle spends less time in any one area. But don’t increase speed so much that you sacrifice print quality. Focus on travel speed first.

Is stringing a sign of a bad printer? Not at all. Every FDM printer strings with default settings. Even expensive machines need retraction tuning for each filament. It’s a normal part of dialing in your setup.

Can I remove strings after printing? Yes. A heat gun on low setting (held 6-8 inches away) will melt away thin strings quickly. You can also use a lighter briefly, but be careful not to deform the print. For small strings, simply pulling them off by hand or with tweezers works fine.