Restrict Texture Painting to a Mask in Blender

Restricting texture painting to a mask in Blender allows you to control exactly where paint is applied, preventing accidental brush strokes on unselected areas of your 3D model. This guide covers the two primary methods to achieve masked texture painting: using Mesh Face Masking directly in Texture Paint mode, and utilizing Image Stencil Masks through the Tool Settings and Shader Editor.

Method 1: Mesh Face Selection Masking

Face selection masking limits your paint brush strokes strictly to highlighted geometry.

  1. Switch to Texture Paint mode in the 3D Viewport.
  2. Click the Paint Mask icon in the top header bar (it looks like a small cube with a highlighted face, located next to the mode selection dropdown). Alternatively, press M.
  3. Select the faces you want to paint on:
    • Press A to select all faces.
    • Press Alt + A (or Option + A on macOS) to deselect all faces.
    • Hold Shift and left-click to select individual faces.
    • Press L while hovering over linked geometry to select connected faces.
  4. Paint on the mesh. Brush strokes will only affect the currently selected faces.

Method 2: Texture Stencil Masking

A stencil mask uses a 2D image (grayscale) to control brush opacity based on black-and-white values, where white allows paint through and black blocks it.

  1. In Texture Paint mode, open the Sidebar by pressing N and navigate to the Tool tab (or open the Properties panel on the right and go to Active Tool and Workspace Settings).
  2. Scroll down to the Mask section and click New to create a mask texture.
  3. Switch to the Texture Properties tab (red checkerboard icon at the bottom of the Properties panel).
  4. Under Type, choose Image or Movie and click Open to load your mask texture, or click New to create a blank black-and-white image.
  5. Return to the Tool settings panel under the Mask dropdown:
    • Set the Mapping to Stencil. A semi-transparent overlay of your mask image will appear in the 3D Viewport.
  6. Position the stencil overlay in your viewport:
    • Right-click + Drag to move the stencil.
    • Shift + Right-click + Drag to scale the stencil.
    • Ctrl + Right-click + Drag to rotate the stencil.
  7. Paint over the stencil overlay. Paint will pass through the white/transparent areas of the mask while black areas remain protected.

Method 3: Painting Directly onto a Mask via Shader Nodes

If you are using a mask to blend two colors or textures nondestructively, you can paint directly onto the mask texture itself.

  1. Open the Shader Editor and set up a Mix Color node combining your two base colors or textures.
  2. Add a new Image Texture node, set it to Non-Color color space, and create a new black image (e.g., named "Paint_Mask").
  3. Connect the Color output of the "Paint_Mask" image node into the Factor input of the Mix Color node.
  4. Select the "Paint_Mask" Image Texture node so it is highlighted in yellow.
  5. Switch the viewport to Texture Paint mode.
  6. In the top bar, ensure your target image is set to "Paint_Mask".
  7. Paint with a white brush to reveal the secondary color/texture, or paint with a black brush to hide it.