How To Clean Stringing on 3D Prints? Complete Guide

Stringing is a common printing flaw that is difficult to correct in your printer and slicer settings. Sometimes, there’s very little you can do to keep it from happening, especially when printing at faster speeds. However, there are plenty of ways to remove stringing and leave your print looking like it came off the printer bed perfectly. 

Here’s how to clean stringing on 3D prints:

1. Blow hot air on the strings.
2. Use a razor blade and sandpaper to remove strings.
3. Check your retraction settings.
4. Disable Z-hop.
5. Use the right print temperature.
6. Ensure your filament is moisture-free.
7. Clean the nozzle.

These stringing solutions work for pre- and post-printing. Let’s expound on each method to decide which option is ideal for you when cleaning stringing on 3D prints.

1. Blow Hot Air on the Strings

Since the filament is thermoplastic, strings will soften when you blow hot air on them. 

You can use a heat gun or hair dryer to soften and pick off stringing, leaving your print with a nice, even finish. Here’s how to do it: 

1. Fire up the hair dryer or heat gun.
2. Set the temperature to high. Low temperatures will not soften the strings. 
3. Blow hot air on the print, starting from farther away and moving closer to it. Be careful not to get too close as the heat may cause yellowish burn marks on the plastic. 
4. While applying heat, cut the hairy parts of your 3D print with a pair of pliers, or you can grasp them with your hands. 
5. Repeat the process on all sides until the object is string-free.

When done correctly, the hot air will melt the hairy parts of the print but leave the solid parts intact.

2. Use a Sharp Tool and Sandpaper to Remove Strings

You can manually scrape off the stringing with a sharp implement and abrasive if you don’t have a heat gun. You can also use the manual method if the hot air doesn’t work as well as you had hoped. 

1. Use a razor blade, wire cutters, or a craft knife to cut off the hairy parts. Target the cut as close to the central print as possible. 
2. Use medium-grit sandpaper to smooth any protrusions that aren’t part of the print design. 

Remember that the strings can be tough to cut through, so you must be careful when handling the razor blade.

3. Check Your Retraction Settings

Retraction is like a pull-back gear that relieves the pressure of melted filament. The retraction settings cause the nozzle to pull back whenever it reaches an empty area, according to the print’s design. 

Although retraction cleans stringing, you should ensure correct timing and retraction speed. 

When you enable retraction settings, you should:

• Ensure the retraction speed is 50mm/s (0.16 ft/s) at the starting point.
• Keep making 5-10 mm/s (0.16-0.03 ft/s) speed adjustments until you get it right.
• Set the refraction distance at 3 mm (0.009 ft), and make adjustments of 1 mm (0.003 ft) until satisfied. 
• Use a setting called “Combing Mode.” This setting allows the extruder to only move over the printed area. 

Unfortunately, retraction rates can be hit and miss. Retraction settings of 50 mm/s (0.16 ft/s) for speed and 5 mm (0.016 ft) for distance may work for some prints and fail for others. So, you will need to keep adjusting the retraction settings for every 3D print until you get it right. 

This video will help you use retraction to control stringing in 3D prints.

4. Disable Z-Hop

The Z-hop (vertical lift) is similar to retraction, but it influences how high the nozzle is on the Z-axis when it is not extruding filament. You can adjust this setting in multiple slicers, including PrusaSlicer and Cura. When you enable Z-hop, the 3D printer will create a gap between the print and nozzle. 

It either lowers the print bed or raises the hotend immediately after filament retraction. 

Although you can configure the Z-hop height in most slicers, it doesn’t always work as intended. In principle, it should prevent stringing. However, sometimes the upward jerk puts pressure on the molten filament in the nozzle, creating new strings. When this happens, you should disable Z-hop. 

Here’s how to disable Z-hop:

1. Find the filament settings tab.
2. Click filament overrides.
3. Scroll to “Lift Z” and adjust the settings to zero. 

5. Use the Right Print Temperature

Sometimes stringing results from high print temperatures. Manufacturers recommend the best temperature range for the various filaments in the market. It is best to work with a temperature closest to the lower range and work your way up until you get to the ideal temps. 

If stringing occurs, lower the temperature and see if this will help. You can work through steps of 5°C (41°F) until you get to the ideal temperature setting.

Filament	Nozzle Temperature	Print Bed Temperature	Fan Speed
ABS	230 – 250°C  (446 – 482°F)	90  – 100°C (194 – 212°F)	50 – 75%
PLA	190 – 210°C (374 – 410°F)	60 – 70°C 140 – 158°F)	100%
PETG	230 – 260°C (446 – 500°F)	60 – 90°C (140 – 194°F)	25 – 50%
HIPS	230 – 240°C (446 – 464°F)	90 – 100°C (194 – 212°F)	0%
SBS	220 – 230°C (428 – 446°F)	60 – 80°C (140 – 176°F)	50 – 100%
Nylon	240 – 260°C (464 – 500°F)	70 – 90°C (158 – 194°F)	0 – 25%
PVA	220 – 230°C(428 – 446°F)	65 – 75°C(149 – 167°F)	0 – 50%

6. Ensure Your Filament Is Moisture-Free

The condition of the filament matters when printing. If it has moisture, the pockets of water will heat up and pop, breaking the plastic’s surface. The plastic will stick to the nozzle, and the extruded parts may be too thin, resulting in stringing. 

Where and how you store your filaments is important. Ensure you keep your filaments in an air-tight container or plastic bag and add a desiccant like silica to maintain the humidity level.

The AQUAPAPA Silica Gel Desiccant (available on Amazon.com) will protect your filament from moisture damage. This pack has 100 pieces of frozen silica gel. To activate it, you should microwave it or place the pack in the oven (200°F or 93°C). 

If the filament is exposed to moisture, you should dry it before using it. You can dry it in the oven or use a food dehydrator. However, you should use the right drying temperature because the filament will weaken or crystallize if it is too high.

Filament Material	Drying Temperature	Drying Period
PLA	40 – 45°C (104 – 113°F)	4 Hours
ABS	80 – 85°C (176 – 185°F)	4 Hours
PETG	60 – 65°C (140 – 150°F)	4 Hours
TPU	40 – 50°C (104 – 122°F)	5 Hours
ASA	120 – 130°C (248 – 266°F)	6 Hours
Nylon	80 – 90°C (176 – 194°F)	12 Hours

7. Clean the Nozzle

One of the habits you should adopt with 3D printing is to clean the nozzle whenever you complete a 3D print. That is because some filament remains in the nozzle, which increases friction and stringing when working on your next print. 

Clean the exterior of the nozzle with a wire brush. You can clean the interior by soaking the nozzle in acetone overnight. The acetone will dissolve the filament residue.

Alternatively, you can use Fused Materials Premium Grade Cleaning Filament (available on Amazon.com). It has excellent heat stability, flushes out residual filament, and easily adapts when you switch between high and low-temperature materials. It also improves your printer’s lifespan since it prevents nozzle clogging. 

Conclusion

It is upsetting when a 3D print progressing well develops stringing. Fortunately, you can take steps to remove the stringing and prevent it from recurring. You may need to use elimination to figure out what is causing the stringing, but even if you don’t find the ideal printer settings to reduce the artifacts, you can always cut or melt off the strings.