How to Use the Fill Tool in Blender Texture Paint

The Fill tool in Blender’s Texture Paint mode is a essential feature designed to rapidly flood large areas, UV islands, or an entire 3D model with a solid color, gradient, or texture pattern. Instead of manually brushing over large surfaces, the Fill tool applies color instantly across the active texture map based on your selected settings. This article provides a quick, clear guide on what the Fill tool is, its key settings, and how to use it effectively in your 3D texturing workflow.

What is the Fill Tool?

The Fill tool acts like the paint bucket tool found in standard 2D image editing software. In Blender, it allows artists to apply color or textures across a 3D mesh's UV map with a single click. It is primarily used for establishing base colors, applying background coats, or quickly re-coloring entire sections of a 3D asset.

Key Settings of the Fill Tool

When you select the Fill tool from the toolbar on the left side of the screen, several key options appear in the Active Tool and Workspace Settings panel:

  • Color / Color Palette: Defines the primary color used to fill the model. You can select a color using the color wheel or pick from a predefined palette.
  • Blend Mode: Determines how the fill color mixes with the existing texture.
    • Mix: Replaces existing pixels with the new color.
    • Multiply: Darkens the underlying texture using the fill color.
    • Overlay/Add/Subtract: Allows for non-destructive color grading and shading effects.
  • Strength: Controls the opacity of the fill operation. A value of 1.0 completely covers the surface, while lower values blend the fill color transparently over the underlying layer.
  • Color Source: Switches the fill type between a solid Color or a Gradient.

How to Use the Fill Tool Step-by-Step

  1. Prepare Your Mesh: Ensure your 3D object is unwrapped (has UV coordinates) and has a material with an active Image Texture assigned.
  2. Enter Texture Paint Mode: Select your object and switch from Object Mode to Texture Paint mode using the top-left mode dropdown menu.
  3. Select the Fill Tool: Click the Fill icon (shaped like a paint bucket) in the toolbar on the left side of the 3D Viewport.
  4. Choose Color and Strength: Adjust your desired base color and ensure the Strength is set to 1.0 for full coverage.
  5. Apply the Fill: Click anywhere on the 3D model in the Viewport, or click directly on the canvas inside the Image Editor window while set to Paint mode.

Useful Tips for the Fill Tool

  • Face Selection Masking: Enable Paint Mask or 3D Viewport Selection Masking in the top header. Select only specific faces or UV islands, then use the Fill tool to color those selected areas without affecting the rest of the mesh.
  • Clearing Textures: To quickly reset a texture map back to a blank canvas, select white (or a default neutral color) and click the mesh with the Fill tool set to Mix at 1.0 strength.
  • Gradient Fills: Switch the Color Source to Gradient in the tool settings to drag and drop smooth color transitions directly across your 3D geometry.