You may or may or may not know/use this Illustrator feature, but Layer Masking is a very under-used feature of the Adobe Illustrator series of software. I'm not talking about making a clipping mask. This is entirely different altogether. By making a “layer mask,” you can save precious time by not having to release and reapply clipping masks, and even better – there's a toggle button in the Layers Palette! Tutorial below.
Like I said before, this is a very under-used feature, so it's been around for a while. I know for a fact that Layer masking is available in CS1+ but anything earlier, I'm not sure. (hopefully you all can help us out with that in the comments)
By creating a path on the very top-most sub layer of each Layer, you can use that path as a mask by toggling the Mask Button in the Layers Pallete. If you hit the masking button without having your desired path on the top, Illustrator will automatically use whatever path is in the top-most sub-layer (or shape layer). So it's very important to make sure the shape you wish to use as a mask is on top of everything else in that layer. Using Layer Masks will save you time by avoiding tedious un-grouping, grouping, releasing, and applying clipping masks with the ease of a simple toggle button. Attention the hierarchy of your layers and sub/shape layers is essential in order to get the most out of this feature, but once you get the hang of it, it should definitely speed up your work flow! You can create a unique layer mask for each and every layer in your Illustrator document. You may practice applying layer masks to the different types of drawings so that you can understand the importance of this under-rated feature. Many people are unaware of this feature and it can ease work for the beginners who find difficulty in going through long steps. Alternative tools are available for all the difficult and time-consuming process in adobe Photoshop.
Let's dive right in:
First, open Illustrator, make a new file, then create a bunch of random shapes on the art board. It takes only three short and handy steps to apply a layer mask. You may fill the specified geometrical shape with some sort of texture to apply it to particular dimensions.
Create a shape to use as your mask
I often find that a layer mask that matches my art board can come in really handy. So I'll be using that as an example. My art board, in this case, is 468 X 350 pixels. To create a mask you can use a variety of tools (any tool that creates a path). In my case I'll be using the Rectangle tool. You may create shape of any sort and size to fill the layer palette. In order to easily make a rectangle at the exact size of your art board, simply click once on the art board without dragging. You will then be able to type in the exact dimensions. Click OK and you will have your rectangle path. (fill and stroke don't matter)
Align your mask to the art board
Now that you have your rectangle, you probably want to align it perfectly to the art board. You can do this easily with the Align palette. (Window > Align) With your shape selected, align it horizontally and vertically to the art board by clicking on these two buttons in the Align palette: (make sure that “Align to Art board” is enabled).
Your shape should now look something like this:
Apply Your Mask
If you haven't already, make sure your path is the top-most path in your layer. [edit: Select the LAYER, not the path,] then click on the Mask toggle button in your Layers palette.
With a single click in the Layers palette, you can now toggle the visiblity of everything in that layer! You just have to make sure that your desired masking path REMAINS ON TOP or “FRONT” of that layer.
Now that you've mastered the art of layer masking, use it to your advantage. You can freely move and modify all of your shapes in the layer without releasing the layer mask! This not only saves a lot of time, but gives you a better visualization of what a finished and/or “cropped” file will look like but with much more workflow freedom than applying individual clipping masks to groups of shapes. You can always toggle the layer mask off with a single click if you need to see everything.
Quick Tip: I like to “lock” my layer mask in the layers palette so I can't ever select or move it's position.
The layer mask can be used to modify the overall appearance of geometric shapes over defined area. It is a lot easier and convenient to do than conventional way of clipping and modifying portion of different geometric shapes separately. Applying a layer mask means that you are creating a layer of defined shape, color and dimensions. Then you are spreading that layer over defined area in the art box. That gives you freedom to do things differently and collectively. The layer masking helps you to ensure that all the colors and other features get spread over a particular area uniformly and precisely. The technique of layer masking can be used to draw landscapes and other calligraphic pictures in a suitable way. You can mask or overlap multiple layers to achieve your desired results.