How Fake User Prevents Data Deletion in Blender

In Blender, unlinked or unused data-blocks—such as materials, textures, actions, and node groups—are automatically purged upon closing and reopening a project file. This article explains what the "Fake User" feature is, how Blender's internal data-management system operates, and why assigning a fake user is necessary to preserve valuable assets from permanent deletion.

How Blender Manages Data-Blocks

Everything in a Blender file is stored as a data-block. When you create an object, a mesh, a material, or a texture, Blender tracks how many other elements in the scene are referencing it. This reference count is known as the "user count."

For example, if you assign a single material to three separate 3D meshes, that material data-block has a user count of three. If you remove the material from all three meshes, its user count drops to zero, turning it into "orphan data."

Why Blender Purges Unused Data

Blender employs an automatic garbage collection system to keep file sizes small and project files clean. When a file is saved and closed, Blender identifies every data-block with zero users and removes it entirely from the file.

While this prevents unnecessary clutter and bloated file sizes from abandoned experiments, it also poses a risk: any unassigned material, custom brush, or unused animation clip you intend to use later will be permanently lost unless it is explicitly protected.

What is a Fake User?

A Fake User is a manual override that assigns an artificial reference to a data-block, raising its user count by one. Even if no actual object, light, or camera in the scene is using that material, texture, or animation action, the data-block still registers as having an active user.

Because the user count remains at one (or higher), Blender's garbage collection system ignores the asset during the file-saving process, ensuring the data persists between sessions.

Key Reasons to Use Fake User Assignment

  • Preserving Asset Libraries in Project Files: Store custom materials, shaders, and geometry node setups within a file without needing dummy placeholder objects in the scene.
  • Saving Animation Actions: In the Action Editor or Non-Linear Animation (NLA) editor, animations that are not actively assigned to an armature will be deleted on file close unless protected with a fake user.
  • Retaining Custom Brushes and Textures: Custom sculpting or texture-painting brushes must be saved with a fake user to avoid re-creating them in future sessions.

How to Assign a Fake User

To assign a fake user to a data-block:

  1. Locate the data-block in its respective editor (such as the Material Properties, Shader Editor, or Action Editor).
  2. Click the Shield icon located next to the data-block's name. When active, the icon displays a checkmark.
  3. Alternatively, switch the Outliner display mode to Orphan Data, right-click any unassigned data-block, and select Add Fake User.