So, what's a mask?
Think of a blank piece of paper strapped to your face. Of course, you can't see through it. To see anything, you're going to have to cut out eye holes. Masking at its most basic form is just that … cutting out eye holes. It should remind you of … well, wearing a mask. Hence the name. (Just to clarify, don't do any cutting with paper strapped to your face. It's dangerous, and potentially very, very messy.)
Thinking of masking as cutting a hole through a blank piece of paper pretty much makes you an expert on the subject. You can mask just about anything, raster images included. Masks show you what you want to see, and hide what you don't.
What are masks good for, anyway?
Well, for starters, they're just another valuable tool at your disposal. Knowing what tools you have to work with and understanding how they work will only help you get on with your job faster (employers love that). As I stated earlier, masks show you what you want seen, and hide what you don't. A classic example of a clipping mask is containing an image within a shape. You want an eye peeping through a keyhole? A clipping mask will do the trick. Another, maybe, less obvious use for a clipping mask is to hide the edges of your artwork (yes, I'm looking at you people who use white boxes to hide the edges of your work).
Enough already, I get it … how do I make one?
1. Create your shapes
You'll need at least two shapes. A masking shape, and the items you wanted masked. Your topmost object is always your vector masking shape (the "hole" you want to cut out of the paper) because if we revisit our paper analogy, you can't have what you want masked sitting in front of the hole … that wouldn't work.
2. Select all of the items you want masked (including the mask itself)
Go to "Object" in your toolbar, and down to Clipping Mask > Make (Command + 7 for Mac users or Control + 7 for PC users). Lo and behold! Your objects have been clipped into your shape.
Once you've made your mask, you can move or edit the elements around to your heart's desire or, conversely, lock them so you won't accidentally move or edit them at all.
Please note: You'll notice your topmost shape has lost any color applied to it. That's because Illustrator assumes you're only using your mask as the (here's that paper analogy again) "hole in the paper" and not a design element. Not to worry, you can easily change that by selecting your mask and by applying fills, strokes or effects to it.
There are a couple of other important functions in the Clipping Mask menu, one of which is "Release.” If you want to release objects from your mask you can either use the direct selection tool (the white arrow) and manually remove them by clicking on the mask and pressing Delete, or select the entire mask using the group selection tool (the black arrow) and under "Object" in the toolbar, click on Clipping Mask > Release (Option + Command + 7 on a Mac, Alt + Control + 7 on a PC). Then go to “Object” and select “Ungroup.”
What else is there?
Clipping Masks are pretty versatile. You can create a mask of your mask, mask raster images, mask non-outlined type, and make a clipping mask of a compound path, for example. Once you're familiar with masks, you'll find a multitude of uses for them.
In Part 2, I‘ll discuss how you can have your masked object fade into transparency.
Anthony Fonseca is a graphic designer in the Greater Toronto Area. You can contact him with questions, comments or invites to masquerade balls by e-mailing him at firstname.lastname@example.org.