Yes, that’s right—the newest Sketchbook Pro update gave us the long awaited feature, the Clipping Mask/Alpha Mask! Let me quickly show you how to use it and why it should become an essential part of your workflow from now on.

how to add clipping mask in sketchbook pro

How to Create an Alpha Mask in Sketchbook Pro

First of all, if you’re familiar with the Clipping Mask feature in other programs, I have to warn you that it looks very different in Sketchbook. So it may seem pretty unhandy at first, but once you see how it works, you may discover you actually like it more!

Step 1

Go to the Layers panel and create a New Group. Grouping layers will help you quickly separate the clipped layers from the non-clipped ones.

create new group

Step 2

Change the Blend Mode of the group to Normal. This will ensure that whatever you do inside the group will not affect the layers outside of it.

change blend mode to normal

Step 3

Create three layers inside the group. Name the upper one Line Art, the middle one Mask, and the lower one Clipped Layer.

create three layers inside group

Step 4

Sketch something on the Line Art layer. Keep it simple, just for the demonstration purposes. You can also download the sketch I’ve used here.

draw the line art
line art example

Step 5

By drawing the line art you’ve created an inside and outside of the object—draw that inside area on the Mask layer using a hard brush.

draw the clipping mask
clipping mask example

Step 6

Time for the most important step: change the Blend Mode of the Mask layer to Alpha Mask. This will make the shape disappear, as it’s no longer a part of the drawing—it’s simply a definition of the area that you want to limit your drawing to.

change blend mode to alpha mask

Step 7

Now go to the Clipped Layer and start drawing whatever you want—Sketchbook will not let you cross the borders defined by the mask!

draw the clipped colors
You can hide the Mask layer to see what you’re really drawing.

Step 8

You can add as many layers below the mask as you want—as long as they’re inside the group, they will be properly clipped. So you can have separate layers for the colors, shadows, shine, textures—all clipped by default! If you want to draw something that is not clipped, just create a layer outside of the group, or above the Mask layer.

add shadows and light
The “cast shadow” layer is outside of the group, so the mask doesn’t affect it.
clipping mask how it works

Step 9

If you want to edit the mask, just paint on it—you can erase it, repaint it, smudge it, move it around, and this will automatically affect the look of the layers below. You can even change the Opacity of the mask to make the clipped layers more transparent!

modify clipping mask
Remember that erasing a part of the mask doesn’t really erase anything below—it just hides that area!

If you want to see the mask before doing these changes, just switch it back to the Normal mode (and maybe lower the Opacity to see the layers below), and then back to Alpha Mask mode once you’re done with the edits.

Step 10

There’s also another new mode, called the Inverse Alpha Mask. You can use this layer to quickly “erase” parts of the layers below just by painting on it.

how to use inverse alpha mask
inverse alpha mask example

Isn’t it the Same as the Lock Transparency Function?

So what’s the difference between this new feature and the Lock Transparency function we’ve been using before for the same purpose? The most important difference is that the Alpha Mask is transparent. You can’t Lock Transparency to a transparent layer—you always have to start with some base color.

Second thing related to it is that you can clip multiple layers to one mask. In the past if I wanted to add a Multiply layer above the color layer, that was clipped to the same area, I had to copy the color layer and fill it with white (which in the Multiply mode renders as transparent). And if I wanted to erase a part of the color layer, I had to erase the same part in all “clipped” layers—because they weren’t really clipped, they were just copied.

The shape of the body is included in all the shading layers in this file. If i wanted to change the shape of the tail, for example, I’d need to edit them all, one by one—whereas if I used a mask, I’d only need to modify the mask.

The third thing is, the Alpha Masks can be stacked! You can create a group inside a group, to mask something that’s already been masked, without actually editing that previous mask. And you’re also free to use the Lock Transparency function in any of the clipped layers, for a “quick” clipping mask.

This may look complicated at first, but give it a try—the effects are instantly visible, so you can freely experiment with masks and learn it all on your own.

That’s All!

As you can see, this is a pretty simple function with endless possibilities. I’ve been using it for a while in the Beta stage, and now I can’t really live without it—it makes the whole process of coloring and shading so much faster!

If you like the concept behind this function, but it still confuses you, please leave a comment—I’ll be happy to help!

Check out my tutorials for other features from the 9.0 update here:

How to Use the Color Editor in Sketchbook Pro 9.0
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How to Use the Brush Set Randomize Mode in Sketchbook Pro 9.0
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