Using the Blob Brush tool

Draw merged paths and automatically remove redundant points so the path is easy to select and edit. Learn how to use the Eraser and Smooth tools.

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Requirements

To complete the tasks demonstrated in this tutorial, you need the following software and files:

Adobe Illustrator CS4

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Sample files

lrvid4018_ai.zip (ZIP, 2.7MB)

Prerequisite knowledge

Basic knowledge of the Illustrator toolbox

Using the Blob Brush tool

The Blob Brush is a convenient new tool in Adobe® Illustrator® CS4. This brush allows you to draw merged paths, and is particularly useful with the addition of a graphics tablet. In this tutorial, you will learn how to use the Blob Brush tool to create filled text. You'll also learn how to integrate the Blob Brush tool with the other tools in the Illustrator toolbox.

The traditional paintbrush

Understanding the traditional Paintbrush tool will give you a better basis of comparison for what the Blob Brush can accomplish. To use the Paintbrush:

1. Choose the Paintbrush from the Illustrator toolbox. The Paintbrush tool allows you to draw freeform paths that have brushes associated with them.

   

   Figure 1: The Paintbrush tool
2. Using a graphics tablet, write a word on the artboard in Illustrator. By default, your word will have a 2-point oval stroke. This setting is displayed in the control panel at the top of the Illustrator window.

   

   Figure 2: The Control panel
3. To change the brush, choose the arrow-shaped Selection tool from the toolbox. Click the word to select the entire path.
4. Go to the control panel and click the down arrow to the right of the Stroke menu. By default, the Brush Style menu is set to 2 pt. oval. A context menu with different brush options appears. Choose the desired brush from the list of options.

   

   Figure 3: Changing the brush size
5. To change the stroke weight, click the arrow next to the Stroke weight box in the Control panel.

   

   Figure 4: Changing the brush size

   Note: You can apply a similar range of brushes and stroke weights using the Paintbrush, Pencil, Pen, and Shape tools.

Using the Blob Brush tool

Whereas painting with other tools creates open paths, the Blob Brush tool paints closed paths that can be filled with various colors. To use the Blob Brush tool:

1. Choose the Blob Brush tool from the toolbox. The Blob Brush tool is located between the Pencil tool and the Eraser tool.
2. Using the stylus for your graphics tablet, write a new word on the Illustrator page. Try joining two or more of the letters, as shown in Figure 5.

   

   Figure 5: Writing with the Blob Brush tool

   Note: Because the Blob Brush is an intuitive tool, you do not have to use any Pathfinder operations to join different objects, or in this case, paths. Every time you overlap one path with another, the Blob Brush tool merges those paths automatically, creating a single shape. You can see this effect more clearly by clicking your word to select it. A blue line, indicating a closed path, appears on the outside of the letters of your word.

   

   Figure 6: Selecting the path created with the Blob Brush tool
3. To paint with a different color, deselect the items on the page. Click the Down arrow for the fill color menu in the control panel. The Color Swatch panel opens. Choose a new color from the available swatches.

   

   Figure 7: Choosing a new fill color
4. Double-click on the Blob Brush tool. The Blob Brush Tool Options dialog box opens.

   

   Figure 8: The Blob Brush Tool Options dialog box
5. To configure your graphics tablet for use with the Blob Brush tool, increase the size and variation values as shown in Figure 8. This will associate the pressure from your graphics stylus with the brush size. Click OK.
6. Paint a line across the word you previously painted with the Blob Brush tool. If you select this shape by choosing the Selection tool and then clicking a point on the path, you will notice that it is a distinct shape from the underlying word.

   

   Figure 9: Painting over a closed path

Modifying a shape

Just as you can modify shapes with the traditional Paintbrush tool, you can also modify shapes using the Blob Brush tool. To modify a shape:

1. Choose the Selection tool. Right-click a point on the line you painted in step 6 in the previous section. A context menu with a range of options appears. Choose Arrange and then choose Send To Back from the context menu that appears. The stroke goes to the back of the layer stack, making the word fully visible again and allowing you to work with it more easily.

   

   Figure 10: Sending a layer to the back of the layer stack
2. To modify the individual letters of the word, select a letter that is not merged with another. Then, double-click the Blob Brush tool to bring up the Blob Brush Tool Options dialog box.
3. Change the size and variation settings to their defaults and turn off the pressure command using the options provided in the Blob Brush Options Tool dialog box as shown in Figure 8.
4. Choose the Selection Limits Merge checkbox. This option provides you with greater control over how the Blob Brush tool merges shapes together.
5. Click OK to accept these modifications. Draw a new stroke over the selected letter and another letter in the word.
6. Choose the Selection tool again and click on a point in the path of the original selected letter. Notice that the selection outline includes only the new stroke and the associated letter. The new stroke does not merge with the other letters in the word.

Integrating the Blob Brush tool with other tools

You can also integrate the Blob Brush tool with other tools in the toolbox. To see how the Blob Brush tool interacts with the Eraser tool:

1. Choose the Eraser tool from the toolbox. Erase a portion of a stroke.
2. You can also smooth a jagged edge of a stroke created with the Blob Brush tool using the Smooth tool. Choose the Smooth tool by pressing and holding on the Pencil icon in the toolbox.

   

   Figure 11: Selecting the Smooth tool

Where to go from here

• Illustrator CS4 Help and Support
• Learn Illustrator CS4
• Introducing Illustrator CS4, by Deke McClelland
• Working with multiple artboards, by Deke McClelland
• Working with gradients, by Deke McClelland
• Lynda.com

This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License

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