Adobe Illustrator CS3 – Using the Eraser Tool

Using the Eraser Tool

Adobe Illustrator CS3 features a new tool called the Eraser tool. Unlike the Path Eraser tool, the Eraser tool works as you would expect—it simply erases parts of objects. That being said, the Eraser tool has a variety of settings, and you should know about some “side effects” as well.

You’ll find the Eraser tool in the lower part of the Tools panel, grouped with the Scissors and Knife tools. To use the Eraser tool, select it, and then click and drag over any object (or objects). If nothing is selected, the Eraser tool will erase all objects across all layers in your document, with the exception of locked layers, of course. For more control, you can make a selection first and then use the Eraser tool, at which time the tool will erase only those objects that are selected (leaving all other objects intact).

The Eraser tool (not to be confused with the Path Eraser tool) is grouped with other tools that cut or sever objects.

A single swipe with the Eraser tool erases all objects in its path.

It’s important to realize that although the Eraser tool is cool and makes it seem effortless to quickly remove parts of an illustration, the tool still must abide by the general rules of how vector objects are drawn. This means if you try to erase part of a single closed path, the result will be two closed paths, not open ones. It’s easiest to see this when attempting to erase paths that contain strokes. In addition, although you can certainly use the Eraser tool to erase portions of a stroke, you must reapply the strokes to each segment of the resulting path. In the latter case, you can get around this by first applying the Object > Path > Outline Stroke command before using the Eraser tool. The same applies when trying to erase paths with brushes applied (refer to Chapter 5, Brushes, Symbols, and Masks, for more information on brushes).

Although you may initially expect the eraser to simply remove an area from an object (left), the result will actually be two closed shapes (right).

If a stroke has the Round Cap option specified, the eraser may appear to create a clean break while you’re using it (left), but the result will be two paths, each with its own respective round cap appearance (right).

You’ll find that the settings for the Eraser tool are quite similar to the Calligraphic Brush settings, which are covered in Chapter 5, Brushes, Symbols, and Masks.

Once you get used to the behavior of the Eraser tool, it becomes a useful (and fun!) tool to use. Even better, you can adjust some really powerful settings to get the full potential of the Eraser tool. First, you can adjust the size of the eraser by tapping the bracket keys on your keyboard (just as you would adjust brush size in Photoshop). You can also double-click the Eraser tool in the Tools panel to open the Eraser Tool Options dialog. You can manually adjust the numerical values for the angle and roundness of the Eraser tool, or you can click and drag the black dots and the arrow in the preview near the top of the dialog to adjust those values visually. You can adjust the size of the diameter of the eraser as well.

The Eraser Tool Options dialog offers control over how the Eraser tool works.

Holding the Option (Alt) key while dragging with the Eraser tool will allow you to erase using a rectangular marquee area. Dragging with the Shift key will constrain the eraser to increments of 45 degrees.

By default, all the values are fixed, meaning they remain consistent as you use the Eraser tool. However, you can choose to make the values random and select a variation for each setting. Even better, if you have a pressure-sensitive tablet (such as the one from Wacom, for example), you can choose other variables including Pressure. For example, setting Diameter to Pressure with a high Variation value gives you the ability to erase with more control and flexibility.

When choosing variable settings such as Pressure, the preview window in the Eraser Tool Options dialog displays the minimum, median, and maximum sizes of the eraser.

By applying pressure with a Variable setting for the eraser, you can achieve natural-looking results not possible with a mouse.