How to Clear Custom Split Normals Data in Blender

Clearing custom split normals data in Blender is a simple process executed through the Object Data Properties tab, which resets an object's shading to default and fixes common visual artifacts often caused by imported 3D models. This guide covers the exact steps to remove custom split normals, explains why they affect your mesh, and details how to manage your smooth shading settings afterward.

Step-by-Step: Removing Custom Split Normals

To remove stored custom normal data from a mesh:

  1. Select the Object: Click on your 3D model in Object Mode.
  2. Open Object Data Properties: In the Properties panel (usually on the right), click on the green triangle icon (Object Data Properties).
  3. Locate Geometry Data: Scroll down to the Geometry Data expandable section.
  4. Clear the Data: Click the Clear Custom Split Normals Data button.

Once clicked, the custom normal data is permanently removed from the selected object, and the button will change to Add Custom Split Normals Data.

Why You Should Clear Custom Split Normals Data

Custom split normals are often generated when importing models from external CAD software, game engines, or file formats like .FBX and .OBJ.

When this data exists on a mesh, it overrides Blender's built-in shading calculations. This can result in:

  • Inflexible Shading: Applying Shade Smooth or Shade Flat does not appear to change the object's appearance.
  • Lighting Artifacts: Shadows and highlights may look distorted or stretched across flat surfaces.
  • Modifier Issues: Modifiers like Bevel or Subdivision Surface may produce strange shading errors.

Removing this data restores default shading controls to Blender, allowing modifiers and auto-smoothing to work correctly.

Managing Shading After Clearing Split Normals

After clearing custom split normals, you can control the object's surface appearance using standard Blender tools:

  • Shade Smooth / Flat: Right-click the object in the viewport and select Shade Smooth or Shade Flat.
  • Smooth by Angle (Blender 4.1 and newer): Right-click the object and choose Shade Auto Smooth, or add a Smooth by Angle modifier from the Modifier panel to dynamically control sharp edges based on face angles.
  • Auto Smooth (Blender 4.0 and older): In the Object Data Properties tab, expand the Normals section, check Auto Smooth, and adjust the angle threshold (default is 30 degrees).