What Do the Red Areas in Cura Mean? (How to Fix Them?)

There is no denying that a successful 3D printing process starts with an optimized 3D model, as a wrongly designed model will automatically cause the process to fail by misinstructing the printer before even any physical factors come into play.

On the other hand, as 3D modeling is a highly complex task, even before the 3D printing part is involved, models can have imperfections that can either appear due to a mistake from the 3D modeler or even due to issues with the 3D modeling software.

Fortunately, slicer software, such as Cura, usually do a great job of telling us what could be wrong with a model before we move on to the printing process, making our life so much easier.

In today’s article, our topic will be red areas appearing on parts of the model in Cura slicer, which points towards the existence of a problem that requires fixing but doesn’t exactly tell us what it is.

So, what do the red areas in Cura mean?

The red areas that appear on the models in Cura are warnings to tell the user that these parts are overhangs and require supports to print successfully.

On the other hand, these red areas can occasionally appear on parts that don’t make much sense (that aren’t overhangs), which often comes down to a faulty model.

Next up, we will analyze the factors that can cause red areas to show up in Cura in more detail and find out how to get rid of these red areas to achieve a successful printing process.

What Do the Red Areas in Cura Mean?

While the red areas in Cura have a definitive meaning behind them, the situation isn’t as simple as it appears due to the possibility of these red areas showing up for different reasons.

The primary reason behind the red areas appearing on a model in Cura is to warn you that these parts are overhangs, requiring supports for a successful printing process.

While it’s possible to ignore the red areas and proceed with the printing process, the lack of supports can cause these parts of the model to droop.

On the other hand, even though showing the overhangs is their primary function, there are times where the red areas start showing up on strange places that aren’t overhangs by any means, such as the bottom of the model or on the vertical walls.

When red areas appear on parts of the model that don’t make sense, the culprit is a faulty model, with problems such as inconsistency in surface normals causing these red areas to show up in Cura.

In such a case, we highly recommend refraining from printing the object until you fix or replace the model, as the chance of failure is pretty high if Cura has a hard time understanding the structure.

How to Fix the Red Areas in Cura?

As a few distinct factors can cause the red areas to show up in Cura, the solution largely depends on finding what exactly has been the factor behind the issue in your case and applying the appropriate fix.

Below are some of the things we recommend trying to fix the red areas in Cura and make your model suitable for printing:

  1. Configure the supports. If the red areas on the model appear due to overhangs that require supports in your case, you shouldn’t have any issues as long as you correctly configure the support settings.
  2. Rotate the model and ensure it touches the build plate. In cases where the red areas are at the bottom of the model or close to the bottom, ensuring that the model is upright and touching the build plate can help remedy the issue.
  3. Apply mesh fixes in Cura. The parameters in the Mesh Fixes category in Cura can help resolve mesh-related problems with your model. That being said, this process will most likely require some trial and error as there are plenty of different things you can activate and deactivate here.
  4. Repair the model in Netfabb. Netfabb is a tool that allows you to analyze and repair models that will be used for 3D printing purposes, which can come in quite handy if the model you’re using is indeed faulty in some way. While it’s a paid tool, you can benefit from the free trial if you have never used it before.
  5. Fix the model in CAD software, or replace it with a new one. While this process requires experience with CAD software, it’s the only solution when the model is flawed and cannot be fixed in any way without modification. On the other hand, replacing the model you’re using by downloading an alternative option is always a solution that saves you from the hassle of fixing the model you have.

In most cases, our recommendation is to replace the model (if possible) you’re using with another one if you’re seeing red areas where there aren’t overhangs, as the effort spent on fixing a flawed model is usually not worth it.

What Are the Blue Lines in Cura?

Another color you will see on your model while using Cura is blue, which comes in two shades; light and dark.

The light blue lines in Cura indicate the travel move paths that the extruder will take with retraction during the printing process, whereas the dark blue lines show the travel move paths where the extruder won’t retract the filament.

Since seeing these lines can be helpful to pinpoint potential issues with stringing before even starting the printing process, we highly recommend analyzing them thoroughly before deciding to continue.

Wrapping Up

While the purpose of the red areas in Cura is to convey a very straightforward piece of information to the user, the possibility of these areas showing up due to unintended factors makes the topic slightly more complex.

To quickly recap, the primary purpose of the red areas in Cura is to let you know that these areas of the model are overhangs and require supports for a successful print where they don’t cause issues such as drooping.

On the other hand, in some cases, Cura can incorrectly display red areas on parts of the model that aren’t overhangs, which often is a sign that the 3D model is faulty, causing Cura to misunderstand it.

Happy printing!