Why Some Faces Appear Dark on a Mesh in Blender and How to Fix It

Why some faces appear dark on a mesh in Blender and how to fix it
Why some faces appear dark on a mesh in Blender and how to fix it

Table of contents

When rendering a mesh with smooth shading enabled, you may notice a dark region or shadow on some faces. Smooth shading on a mesh with ngons produces a more notable appearance, with the ngons going black when rendered.

Why some faces appear dark on your mesh in Blender

‘Normals’ are the reason why some of your mesh’s faces are darker than the rest. Your Normals are not facing the correct direction.

What are Normals in Blender?

A perpendicular line to a surface, a line, a curve, or even a point is referred to as a normal. The average of all the vertices of a face in Blender is presented relative to the point of view in the 3D workspace as the face’s normal. The inclination and location of planes in space can be defined with the use of normals.

A visualization of face normals of a UV Sphere in Blender
A visualization of face normals of a UV Sphere in Blender

Each blue line in the diagram above represents the normal for a face on the sphere. Each line is perpendicular to the face on which it is drawn. You can turn on normals visualization in the Mesh Display panel.

How normals cause some areas of a mesh to be dark than the rest

When sculpting a 3D model on Blender or just manually changing the edges or faces of a model, sometimes normals get “flipped”. They change direction to the opposite of their optimal direction. Ideally, normals should be facing outward in relation to an object.

This problem leads to the creation of some dark spaces in the 3D model, which can ruin its final look.

How to fix dark faces on your mesh in Blender

Recalculate the normals of your model to make it as clean as possible to eliminate dark regions on your mesh. Here is how you recalculate normals in Blender:

How to access recalculate and flip normals operators in Blender
How to access recalculate and flip normals operators in Blender
  • Select your mesh and press the TAB key to enter Edit Mode
  • Select all faces on your mesh by pressing the ‘A’ key
  • Press Shift + N + K or under Mesh > Normals > Recalculate … (The entire menu can also be accessed by pressing Alt + N).
  • Then flip normals of selected faces while in Edit mode by going to the 3D Viewport Header. Then go to Mesh > Faces > Flip Normals

Or, if you want to quickly fix all the normals in your mesh, while in Edit mode you can use Recalculate Normals:

  • 3D Viewport Header > Mesh > Normals > Recalculate Outside (CTRL + N)
  • 3D Viewport Header > Mesh > Normals > Recalculate Inside (SHIFT +CTRL + N)

Note that normals will only be recalculated for selected faces, so you probably want to select all (A) before recalculating.

A comparison of before and after recalculation and fliping of normals in Blender
A comparison of before and after recalculation and fliping of normals in Blender
A Blender interface screen recording demonstrating the utilization of the Product Rendering Tools Addon in Blender.
Get Product Rendering Tools Addon

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