How to Activate the Brush Tool in After Effects

There's a handy tool to create frame-by-frame animations in After Effects called the Brush Tool. 

That feature, which also works to generate cool effects like neon lights over your compositions, is next to the Text tool. However, although at first glance, it looks like you can use it at any time once you click on its icon, there are a couple of things you need to keep in mind to enable it and make it work properly. Here's how you can activate the Brush tool in After Effects.

Creating and selecting a solid layer to use the Brush Tool

When you create a new composition in After Effects, what appears in your interface is a white, black or transparent screen ready to receive either a video that you will import from your files or a Layer on which you can work and add effects.

Well, in this opportunity, we will work with the second option so that you know how to activate the Brush Tool properly. The first thing, therefore, is to create a new composition. Once you have it:

1. Create a new Solid layer by holding down Ctrl + Y or Cmd + Y if you are working on macOS.
2. Choose your preferred background color and hit Ok.

If you would like to activate the Brush tool right now, you won't be able to. Just go to the Toolbar and click on the brush icon next to the Text tool to prove that although you can select this feature, the cursor does not change its shape, which means if you try to draw anything on your canvas, you will not be able to. Instead, a warning window will pop up.

That happens because you have not selected the correct layer; you've imported video or created a solid background, as we did for this exercise in the previous steps. 

If you look closely at your workspace, at the top of your main screen, there is a label with an unlocked padlock called Composition.

You must change that selection if you want to activate the Brush Tool properly. Here's how you can do it:

1. Go to the Timeline and double-click on your Solid layer in the layers area.
2.  Look back at the Composition window and notice how a new label appears at the top with the name of the layer you just selected.

3. Activate the Brush Tool in the Toolbar or by clicking Ctrl + B or Cmd + B and check that the cursor has changed its shape.

4. Draw freely on your canvas.

While you will need these steps to activate the Brush Tool properly, they are also necessary to enable the Clone and Eraser tools. So be sure to select the layer you want to work on the next time you want to use any of these three After Effects features.