Opacity Masks in Illustrator
When you are trying to learn new software, it can be difficult to find your way around. You may not know the terms to look for, or you may not know where to look to find what you are looking for. If you are transitioning from another program, such as Photoshop, you may be used to certain terminology. When using Illustrator, you may be looking for something that isn’t even there. In Photoshop, if you want to blend something or fade it gradually, you would use a layer mask. In Illustrator, you don’t have layer masks. To blend or fade away a portion of an object, you use something called an opacity mask. You can also control the opacity of gradients and mesh points, but an opacity mask has its uses.
This isn’t so straightforward, especially if you are used to layer masks in Photoshop. I will show you how to create an Opacity mask in Illustrator. It isn’t necessarily difficult, you just have to know where to look. Create a New Document in Illustrator. It can be any size that you want. I created a new document that is 1024px x 768px. I am using text to illustrate this method, and the text shown below is Myriad Pro Bold at 222pt size. I filled it with a medium blue.
Next, Select the Rectangle Tool and draw a rectangle over the bottom half of the text. Fill it with white. Then, make a copy of the rectangle by hitting Command/Ctrl + C. The paste in front by hitting Command/Ctrl + F. This automatically places a copy of the rectangle in front of the currently selected object.
As you can see below, I moved the copy (just so you could see that there are two rectangles). You won’t want to move your rectangles at all. With the top rectangle still selected, change the fill to a liner gradient. To make the gradient fade in the direction that I wanted it to go, I had to change the angle to -90°.
Now Select Both rectangles, but not the text. Remember that they are on top of each other. you may have to click and drag your mouse over the right hand or left hand side of the rectangle to avoid selecting the text as well.
Go to the Transparency Panel on the side and click the flyout menu. Then, select Make Opacity Mask.
What happens is that the gradient rectangle acts just like a layer mask in Photoshop. Anything white is left untouched, but anything that is a shade darker than white (light grey to black) is masked out. The closer that area is to black, the higher amount of transparency that will be applied.
The Problem now is that we still have the bounding box of the rectangle to contend with. If you try to place something near the text, you will see the opacity mask and it may interfere with other objects. Select the text and copy it to your clipboard. Then, just as we did with the rectangle, hit Command/Ctrl +F to paste it in front. Go to Object> Arrange> Bring to front.
Then select the rectangle and the top layer of text. Hit Command/Ctrl +7 to make a clipping path, clipping the opacity mask to the shape of the text, as shown below.
Conclusion
Opacity masks in Illustrator aren’t difficult to master, but you might have worked in Illustrator for a long time and not even known that they were there. This technique is simple and easy to use, and you can combine it with other techniques to create realistic vector illustrations. Opacity masks are just another tool to help make your life easier when working in Illustrator. Have you found an interesting use for opacity masks in Illustrator? Do you have a tip to share regarding opacity masks? Share your thoughts in the comments section below.
