Introduced in version 5X, the Procreate color fill tool works differently than similar tools from other design applications. While it offers numerous options for filling in different shapes and selections, it has several quirks that can confuse new users. One of these quirks is leaving lines in the fill area.

The Procreate fill tool leaves behind lines for a variety of reasons, but the most common culprit is the fill threshold setting. This setting defines how much space the tool fills and it can leave lines if it is too small. As such, you can try a larger threshold to remove the lines.

However, you only have access to the color fill threshold setting while you use the color fill tool. As a result, many people overlook it. By reading further, you will learn how to access the threshold option and how you can use it to remove the excess lines from your art.

Why does the Procreate Color Fill Tool Leaves Lines?

Filling an area with color is one of the more basic functions of a graphics design application. This feature usually takes the form of a “bucket tool” that lets you select your color followed by the continuous area to fill. However, this is not the case with Procreate.

The iPad application has no bucket tool at least not in the traditional sense. Instead, it uses the color selection disc as a paintbrush which you must drag over the area to color. While this sounds simple, it does require you to perform specific procedures to fill in certain shapes. It is through these procedures that the tool may leave lines in its wake.

Color Filling in Procreate

To reiterate, your only option to fill an area with color in Procreate is to take and hold the color disc in the top-right corner of the screen. You then drag it to where you want to fill and release it. Procreate then fill the area with the currently selected color.

This basic procedure works for everything on your canvas with slight modifications:

• Objects: tap, drag, and drop the color disc inside the object
• Layers: tap the layer twice in the Layers menu, then select Fill Layer from the popup submenu
• Selections: define your selected area using any selection tool, then select the Color Fill option from the popup menu. If you enabled the auto-fill option, Procreate will fill all-new selections automatically.

The Procreate Color Fill Tool Leaves Artifacts

While these procedures work in most cases, they are not perfect. The software uses an internal algorithm to mark the boundaries of the fill area. This works fine with simple shapes, but it can break down when dealing with anything complex. At which point, the tool may leave uncolored regions called artifacts. It is these artifacts that show up as the errant lines you see.

How to Remove the Errant Fill Lines

While the lines are artifacts of the filling process, they are not a death sentence for your artwork. There are ways to deal with them. Some of these ways are more involved than others, but all of them will fix your issues. The key is to modify the fill algorithm.

As mentioned above, Procreate uses a built-in algorithm to fill areas with color. This algorithm tries to interpret your drawing to mark off where the area boundaries are. It uses a variety of configuration settings to determine how aggressive it should be doing this. Varying these settings will solve your issue.

Fortunately, most people only need to modify a single setting. Called Fill Threshold, this setting tells Procreate how to identify a line on the Canvas. It comes as a slider from 1 to 100, though it works in the opposite way you might think.

Using the Fill Threshold to Remove Errant Fill Lines

However, unlike Procreate’s other configuration settings, The Fill Threshold slider is not a separate tool or menu. Instead, you must access it while using the Fill tool. Luckily, you can do it all in a single motion with the following steps:

1. Choose the area to fill as mentioned before
2. Choose your fill color
3. Tap and hold the color disc in the corner of the screen
4. Drag and hold the disc to the Threshold setting on the top edge of the screen
5. Hover and hold the color circle over your desired threshold setting. Choose a higher number if you need more color and a lower number for less color.
6. Drag the color disc to the fill area and release

You can repeat the procedure as often as you need until you get your desired result. Once you selected the right threshold, the lines should go away immediately.

Just be careful to not set the threshold too high or too low, as they can cause other graphical issues. For instance, you can end up filling the entire screen if the setting is too high. Fortunately, readjusting the threshold should fix these other issues as well.

Use Transparency and Smaller Boundary Lines to Remove Errant Fill Lines

Modifying the threshold setting should fix most errant fill lines, but the setting does not work alone. Procreate defines boundaries and changes in color. Any color change will do. Normally, this just means different colored shapes, areas, lines, selection boxes, and so forth, but it could also mean different layers of a gradient.

Your artwork may have accidental gradients everywhere. Some of the more common ones are object layering and line size. Digital artwork is pixelated by nature. As such, color changes are rarely smooth. Solid lines may not be solid. To you, this imperfection may appear irrelevant, but they can mess up computer algorithms such as the one Procreate uses to fill.

Luckily, there is a workaround for this issue:

1. Make the layer transparent by using the Layer>Transparency menu to let the app know to ignore any background color
2. Make your boundary lines as thin as possible
3. Adjust the fill threshold as above

Conclusion

While Procreate has a color fill tool, it works differently than similar tools from other applications. While these differences have their perks, they can also leave artifacts such as uncolored lines. You can fix these issues quickly by changing how Procreate determines boundary lines.