How to Fix Blobs and Zits on 3D Prints: A Comprehensive Guide


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Ever found yourself staring at a freshly printed 3D model, only to notice those pesky blobs and zits marring its surface? Yeah, me too. It’s a common headache in the 3D printing world, where these little imperfections can turn a perfect model into a flawed one.

Tackling these issues isn’t just about aesthetics; it’s crucial for the overall quality and functionality of your prints. In this post, we’re diving into the nitty-gritty of how to fix blobs and zits on 3D prints.

Trust me, it’s a game-changer for anyone in the 3D printing community looking to elevate their craft.

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Understanding Blobs and Zits in 3D Printing

1. Definition and Appearance

Blobs and zits on 3D prints are like those uninvited guests at a party – they just show up.

Picture this: you’ve got your model fresh off the printer, and there they are, small, bumpy imperfections dotting the surface. These aren’t just tiny nuisances; they can be quite the eyesore, especially on prints where detail is key.

zits and blobs typically look like over extrusion donnysaysvacuum via reddit 210825 download | 3D Gear Guide

2. Common Causes

Diving into the causes, it’s a bit like playing detective with your printer settings.

i. Over-extrusion: Imagine your printer getting a bit too generous, squirting out more filament than needed. That’s over-extrusion for you. It’s like using too much frosting on a cake – sure, it’s extra, but it messes up the final look.

ii. Incorrect Retraction Settings: Retraction is supposed to be the hero, pulling back filament to prevent oozing as the printer head moves. Get it wrong, and it’s like a poorly timed dance move, leaving behind a trail of unwanted filament blobs.


Optimal retraction prevents stringing, yet excessive or insufficient retraction may lead to zits and blobs.

iii. High Printing Temperature: Crank up the heat too much, and your filament flows like lava – too fluid and uncontrollable. This often leads to excess material oozing out where it’s not supposed to.

iv. Fast Printing Speed: Speeding through a print job might save time, but it’s like rushing through a painting. The faster the movement, the more likely you are to have slips and spills – in this case, blobs and zits.

v. Insufficient Cooling: Cooling is crucial. Without it, the filament doesn’t set quickly, leading to sagging and deformation – imagine trying to build with melting Lego bricks. Not pretty, right?

Each of these factors plays a part in the blob and zit saga of 3D printing. It’s about finding that sweet spot in your printer settings where everything just works in harmony.

Pre-Printing Strategies to Prevent Blobs and Zits

1. Proper Calibration of 3D Printer

Before you even think about hitting ‘print’, make sure your machine is in tip-top shape. Calibration is key. It’s similar to tuning a guitar ahead of a concert.

You want to ensure that the bed is level, the extruder is at the right height, and everything moves smoothly. A well-calibrated printer is less likely to give you grief with blobs and zits.

2. Choosing the Right Filament

Not all filaments are created equal, and your choice can make or break your print. It’s akin to selecting the perfect ingredients for a recipe—some materials are more prone to issues than others.

For instance, PLA is generally more forgiving, while ABS can be a bit of a diva. Consider the filament’s quality, compatibility with your printer, and the object you’re printing.

3. Importance of Optimal Slicer Settings

The slicer is your 3D printing playbook. Getting these settings right can be a game-changer.

Test the Right Retraction Settings | 3D Gear Guide

i. Retraction Settings: Retraction is like the ebb and flow of the sea. Too much or too little, and you’ll have problems. Find the sweet spot where your printer pulls back just enough filament during movements to prevent oozing without causing gaps.

ii. Print Speed Adjustments: Speed is a double-edged sword. Go too fast, and you risk imperfections. Too slow, and you might face other issues. It’s about finding that perfect pace where your printer can lay down filament smoothly and accurately.

iii. Temperature Control: Here, it’s all about finding the sweet spot—not too hot, not too cold. Every filament type has its own optimal temperature range. Straying too far from it can lead to blobs or zits, so it pays to stick to recommended settings and adjust as needed based on your printer’s performance and the ambient conditions.

In-Print Adjustments and Monitoring

1. Monitoring Print Progress

Keeping an eye on your print is like babysitting. You can’t just set it and forget it. I’ve learned the hard way that watching the first few layers is crucial.

It’s like the foundation of a building; if it’s shaky, the whole thing can come tumbling down. Spotting a problem early, like a small blob or a slight zit, can save you from a world of frustration later.

2. Adjusting Settings Mid-Print

Here’s where things get a bit techy but super useful. Did you know you can actually tweak some settings while your print is running? It’s like adjusting the sails of a boat mid-journey.

If you notice the filament is coming out too hot and blobby, a slight temperature adjustment can be your quick fix. Or, if it’s speed causing the issue, slowing down the print can sometimes do the trick.

3. Identifying and Addressing Immediate Issues

It’s all about being proactive, not reactive. When you see something off, like the filament not sticking properly or small zits forming, it’s time to act.

Adjusting the bed temperature or recalibrating the nozzle height mid-print can be your saving grace. Think of it as performing a little surgery; a small intervention can save the patient – in this case, your print.

Post-Printing Solutions

1. Sanding and Smoothing Techniques

Once your print is done, it’s not the end of the story if you spot blobs and zits. Grab some sandpaper and get to work. It’s like giving your print a spa treatment.

Start with a coarser grit to tackle the bigger imperfections and gradually move to finer grits for a smooth finish. Patience is key here; think of it as sculpting your masterpiece.

2. Using Chemical Treatments for Smoothing

Chemicals can be your allies in achieving that glass-like surface. For materials like ABS, a little acetone bath works wonders. It’s like marinating your print to bring out its best features.

The acetone gently melts the outer layer, smoothing out those pesky blobs and zits. Remember, safety first – use gloves and work in a well-ventilated area.

3. Heat Treatments for Surface Perfection

Sometimes, a bit of heat is all you need. Using a heat gun can soften the surface just enough to blend those imperfections away. It’s a delicate process, like cooking a gourmet dish; too much heat and you’ll ruin it, just enough and it’s perfect.

Keep the gun moving and don’t linger too long in one spot. With a bit of practice, you’ll get a feel for the perfect temperature and technique.

Advanced Tips and Tricks

1. Utilizing Coasting and Wiping Settings

Diving into slicer settings, coasting and wiping are like the secret spices in your 3D printing recipe. Coasting stops extrusion just before the end of a print path, using the built-up pressure to finish the job.

It’s like coasting your bike downhill. Wiping, on the other hand, drags the nozzle across the print to reduce blobs. It’s akin to smoothing frosting on a cake for that perfect finish.

2. Testing different layer heights

Layer height can dramatically change your print’s look and feel. Playing around with this setting is like adjusting the focus on a camera. Finer layers can reduce visibility of zits but take longer.

Sometimes, a slightly thicker layer can hide those imperfections while speeding up the print. It’s about discovering the ideal point for your particular project.

3. Advanced Slicer Features for Better Results

Slicers are packed with features that can turn a good print into a great one. Think of it as having a toolbox; each tool has its specific purpose.

Features like adaptive layers, ironing, or even variable layer heights can significantly enhance your print quality. It’s like having a set of fine brushes for a painter – they open up a whole new world of detail and precision.

Troubleshooting Specific Blob and Zit Issues

1. Addressing First Layer Blobs

First layer blobs can be a real mood killer. They’re often a sign that your nozzle is too close to the bed, squishing out filament like toothpaste. A quick fix? Re-adjust your bed leveling.

Consider it as preparing the stage for the main performance. Ensuring a perfect gap between the nozzle and bed is like finding the right distance for a projector to get a clear image.

2. Eliminating Zits on Overhangs and Curves

Zits on overhangs and curves are like those tricky corners when painting a room. The key here is cooling and speed. Boosting the cooling fan speed helps set the filament faster, preventing those zits from forming.

 Zits on Overhangs and Curves

Also, slowing down on these tricky parts gives your print time to settle nicely. It’s a bit like driving; you slow down on curves for a smoother ride.

3. Dealing with Blobs on Corners and Edges

Blobs on corners and edges are often due to the printer pausing or changing direction. This is where tweaking acceleration and jerk settings come into play.

It’s like fine-tuning the suspension on a car for a smoother ride. Lowering these settings can reduce the pressure build-up in the nozzle at these critical points, leading to a cleaner print.

For Ender 2 Pro users, this video is invaluable for effectively addressing blob issues. Make sure to check it out.

Maintenance Tips to Avoid Future Issues

1. Regular Cleaning and Maintenance of the Printer

Keeping your 3D printer clean is like taking care of a car; regular maintenance is essential. Dust and debris can clog up the works, leading to all sorts of printing nightmares.

A routine cleanup, especially around the extruder and the build plate, can make a world of difference. It’s like clearing the stage before each performance, ensuring everything runs smoothly.

2. Keeping Filament Dry and Clean

Filament is your 3D printer’s food, and just like any food, it needs to be kept fresh. Moisture is the enemy here. It can sneak into your filament and cause it to bubble and pop mid-print, leaving you with a less-than-perfect finish.

Storing your filament in a dry, clean place is like keeping your ingredients in top condition for that perfect recipe.

3. Firmware Updates and Upgrades

Updating your printer’s firmware is like giving it a new brain. These updates often come with fixes for known issues and can improve your printer’s performance.

It’s like updating the OS on your phone; you get the latest features and optimizations. Regularly checking for firmware updates can keep your printer ahead of the curve, reducing the chances of blobs and zits in future prints.


So, we’ve journeyed through the maze of tackling blobs and zits in 3D printing. From fine-tuning your printer’s settings to post-print polishing techniques, it’s clear that a little attention to detail goes a long way.

Remember, each print is a learning opportunity. Don’t be disheartened by imperfections; instead, use them as stepping stones to refine your skills. Keep experimenting, keep adjusting, and most importantly, keep printing.

The path to flawless prints is paved with trials, errors, and triumphs. Keep at it, and you’ll be amazed at what you can achieve.

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