How To Clean a Hotend Covered in Plastic

Every 3D printer user will likely have a hotend covered in plastic sooner or later due to a failed print, hardware change, unique setting, or other reasons. The only difference will be the severity of the mess you must deal with. So, if you want to be ready for the reality of 3D printing, you must know how to clean a hotend covered in plastic. 

You can clean a hotend covered in plastic by removing the spool and preheating the 3D printer to a temperature higher than the setting for the specific filament. You may also use a heat gun and pliers to remove the blobs or a brass brush to clean plastic residue.

Want to learn how to clean a plastic-covered hotend? I’ll guide you through all the steps and teach you some tricks along the way to make de-clogging and nozzle cleaning quick and painless. Let’s get into it!

1. Remove the Filament Spool From Your 3D Printer

Filament oozing and stringing are common issues with 3D printers. Still, such glitches don’t always lead to an enormous mess of the hotend, albeit your print will still likely fail to an extent.

A gigantic plastic blob covering the hotend, on the other hand, is typically due to the nozzle picking up one or more layers from the print bed at any printing stage. If you aren’t around to monitor and stop the 3D print, your hotend will probably have fused and hardened filament on and around it. 

To make the removal process easier and ensure that you don’t just add the mess, you’ll need to unload your filament. Unloading can be tricky if it’s connected to the congealed filament on your hotend, but it’s possible with a bit of a preheat. 

If your normal unload cycle does not work, you can cut the filament off from the extruder, whether a Bowden tube or direct drive. Don’t forcibly pull the filament out of the extractor if the hotend and nozzle are cold.

2. Preheat the Nozzle To Melt the Plastic on the Hotend

Preheating the 3D printer nozzle should melt the plastic blob covering the hotend. You can then remove and dispose of it safely. 

To do so, preheat the 3D printer nozzle to a temperature slightly higher than what you normally use for the particular filament. Increasing the temperature by 30 to 50 degrees should do the trick. 

For example, if you 3D print with PLA at 210°C to 230°C (410°F to 446°F), preheat the printer nozzle to 250°C (482°F). If the filament is ABS, and you print it at 240°C to 270°C (464°F to 518°F), preheat the 3D printer nozzle to 280°C (536°F).

As the hotend and nozzle reach the set temperature, the hardened filament or plastic will soften enough for you to remove it.

Here’s an official Prusa troubleshooting video to help you through this process:

If the plastic covering the hotend is too large, extending beyond the nozzle or heater block, you may find some filament on other parts of the extruder. A preheated nozzle may not melt all of this filament, especially if there is some plastic above the heat break or covering the heat sink.

3. Use Pliers To Grab and Pull the Plastic Away

You can use pliers to remove the melting plastic when the nozzle is sufficiently hot. Do so gently so that you don’t inadvertently pull rigid plastic that may be covering the thermistor wires or any other part of the extruder. 

Use the same pliers to grab and pull any residual plastic off the hotend gently. If all the residual plastic is gone, you can move to the 6th or 7th step in this guide, depending on the condition of your hotend, nozzle, etc. Otherwise, continue with step 4.

4. Clean Any Plastic Residue With a Brass or Metal Brush

Turn off the 3D printer after removing the bulk of the plastic covering the hotend. Let the hotend and nozzle cool. Get a brass or metal brush to scrape off any softened plastic residue gently. 

Do not use a steel brush, as steel may leave rustable residue on the hotend and nozzle. 

Don’t use a brush on molten plastic, like the filament condition at the end of step 2, as you will have another mess to deal with due to smudging the melting material and sporadic hardening on the hotend. Wait for the hotend or nozzle to cool by up to 100°C (180°F).

In other words, allow the nozzle temperature to drop from:

• 250°C (482°F) to around 150°C or 160°C (302°F or 320°F) for PLA.
• 280°C (536°F) to around 200°C or 210°C (392°F or 410°F) for ABS.

The melting points of PLA and ABS will make these filaments soft enough at the temperatures above for you to remove the plastic from the hotend using a brush. But the plastic won’t melt to the extent that it becomes a gooey and unmanageable mess.

5. You May Also Use a Heat Gun, Kiln, or Oven (Optional)

You can use a heat gun without preheating the 3D printer nozzle if you want to target specific areas on the hotend that are covered by plastic. Also, you may need to use a heat gun if there’s any plastic covering the heat sink or other parts of the extruder and hotend that won’t get as hot.

The other options are a kiln or oven, albeit not the one you use for cooking. Using a kiln or oven is not advisable unless you have a fume hood with active carbon and HEPA filters. You will need the kiln or oven temperature to be as high as 400°C (752°F), which might emit toxic gasses.

A heat gun and pliers or a brass brush are an effective and handy combination. You can target as little or as much of the hotend covered in plastic. This cleaning method can complement the preheating option, or you may use only a heat gun if you have a scattered mess on the hotend.

6. Use Needles and Tweezers To Clean the Hotend/Nozzle

You don’t need this step if your hotend and nozzle are already clean. Still, if the nozzle is clogged or there is any residual plastic inside the hotend, you will need needles and tweezers to clean that debris to ensure there is no blockage.

Also, you may perform a hot or cold pull to remove any residual filament inside the hotend and nozzle. You need to restore the spool and set up the filament again, so checking whether or not the nozzle is clean is a prerequisite.

7. Dissolve Leftover Plastic in a Filament-Specific Solvent

Suppose you cannot remove some rigid residue from the hotend or nozzle with a needle or the hot and cold pull methods. In such a scenario, you need to use a solvent that can dissolve the filament.

You can dissolve ABS in acetone and PLA in ethyl acetate. Just dip the nozzle into the solvent and let the filament dissolve. Rinse and dry the nozzle before reusing it. You may use acetone for PLA, but the solvent will only partially dissolve this filament.

The other solvents that can dissolve PLA aren’t safe for use in a home or by untrained users, such as:

• Chloroform
• Hot benzene
• Tetrahydrofuran

Final Thoughts

To clean a hotend covered in plastic, set preheating temperatures relevant to the type of filament you have. Wear gloves, a mask, and protective glasses if you are unsure how the plastic will melt as you preheat the nozzle, or use a heat gun. 

Consider referring to the filament safety data sheet and the printer’s manual.