The fastest way: use the bucket fill tool on a separate layer

Open your line art in Clip Studio Paint. Create a new layer above or below your line art layer — go to Layer menu, then New Layer. Set this new layer to Multiply blend mode if you want the color to darken what's underneath, or Screen if you want it to lighten. This keeps your original line art intact while you add color on top.

Select the Bucket Fill Tool from the toolbar on the left (it looks like a paint bucket). Pick your new color from the color palette. Click inside the areas you want to fill. The bucket respects the boundaries of your lines, so it won't spill into adjacent sections unless your lines have gaps.

If the bucket fill is leaking into areas it shouldn't, your lines have small breaks. Use the Pencil Tool or Pen Tool to close those gaps before filling again.

Key Takeaways

  • Create a new layer set to Multiply or Screen blend mode, then use the Bucket Fill Tool to add color without changing your original lines.
  • The Bucket Fill Tool respects line boundaries, but only if your lines have no gaps — use the Pencil Tool to close breaks before filling.
  • If you want to recolor existing line art directly, select the line layer and use Select by Color, then fill the selection with a new color.
  • Adjust the Bucket Fill Tool's anti-alias and feather settings in the tool options to control how cleanly the color fills meet your lines.

Recoloring lines directly without a separate layer

If you want to change the color of the lines themselves rather than add color underneath, work on the line art layer directly. Go to Select menu and choose Select by Color. Click on a line in the color you want to change. This selects all pixels of that exact color across the entire layer.

Once the selection is active, pick your new color from the color palette. Go to Edit menu, then Fill with Foreground Color. The selected lines change to your new color when ready. Deselect by pressing Ctrl+Shift+A (Windows) or Cmd+Shift+A (Mac).

This method works best when your line art uses solid, distinct colors. If your lines are anti-aliased (slightly blurred at the edges), the selection may not catch every pixel, leaving thin halos of the old color.

Using the Hue/Saturation adjustment for a softer shift

If you want to shift the color of existing lines without replacing it entirely, use an adjustment layer. Go to Layer menu, then New Correction Layer, then Hue/Saturation. This creates a layer that changes the hue of everything below it without permanently altering your line art.

In the Hue/Saturation panel, drag the Hue slider left or right to rotate the color wheel. Adjust Saturation to make colors more or less vivid. You can target specific color ranges — for example, shift only the reds while leaving blues untouched — by clicking the color buttons at the top of the panel.

Adjustment layers are non-destructive, meaning you can change or delete them later without affecting your original line art. This is useful when you're experimenting with different color schemes.

Fixing gaps in your line art before filling

The Bucket Fill Tool stops at line breaks, even tiny ones. If color is leaking where it shouldn't, zoom in to 200% or higher and look for gaps. Use the Pencil Tool or Pen Tool to draw short strokes that close the break. Match the line color and thickness to the surrounding lines so the repair is invisible.

Alternatively, increase the Gap Tolerance setting in the Bucket Fill Tool options. This tells the tool to treat small gaps as closed. Start at 1 or 2 pixels and increase gradually — too high a value will cause the bucket to fill across intentional gaps.

Controlling how the bucket fill meets your lines

The Bucket Fill Tool has two settings that affect edge quality: Anti-alias and Feather. Anti-alias is usually on by default and creates a smooth transition at the edge of the fill. Turn it off if you want a hard, crisp edge with no blending.

Feather adds a soft blur to the edge of your fill. A feather value of 0 gives you a clean line; higher values (5 to 10) create a gradient fade. For line art, keep feather at 0 unless you specifically want a soft effect.

Both settings live in the Tool Options panel, usually docked on the right side of the screen. If you don't see it, go to Window menu and select Tool Options.

Coloring complex line art with multiple colors

For detailed illustrations with many colors, create one new layer per color or per section. This gives you maximum control and makes it straightforward to adjust individual colors later. Name each layer clearly — "skin tones," "clothing," "background" — so you don't lose track.

Set all color layers to Multiply or Screen blend mode so they interact naturally with the line art. Fill each section with the Bucket Fill Tool. If you make a mistake, undo with Ctrl+Z (Windows) or Cmd+Z (Mac), or straightforward erase that layer and start over — your line art stays safe on its own layer.

Frequently Asked Questions

Why is the bucket fill tool not working on my line art?

The most common reason is gaps in your lines. Zoom in and look for breaks where the bucket can leak through. You can also increase the Gap Tolerance setting in the tool options, or switch to Select by Color and fill the selection instead, which is more forgiving of small breaks.

Can I change the color of just part of a line?

Yes. Use the Pencil or Pen Tool to select just the section you want to recolor, or use Select by Color and then manually erase the parts of the selection you don't want to change. Then fill the remaining selection with your new color.

What's the difference between Multiply and Screen blend modes?

Multiply darkens the lines and makes them blend with what's underneath, like laying colored ink over paper. Screen lightens everything and works well for bright, glowing effects. For most line art coloring, Multiply is the standard choice.

How do I undo a bucket fill if I made a mistake?

Press Ctrl+Z (Windows) or Cmd+Z (Mac) to undo the last action. If you're working on a separate layer, you can also just delete that layer and start over without affecting your line art.

Can I change line color on a locked layer?

No. If your line art layer is locked, you cannot edit it. Right-click the layer in the Layers panel and select Unlock Layer, or click the lock icon next to the layer name to toggle it off.