4. Illustrator brush basics

Note 1: This section applies to the ‘traditional’ Illustrator Paintbrush tool -not the so-called “Blob Brush” that was added to the newer Illustrator versions recently.

Note 2: To use the Illustrator paintbrush tool to the full extend, you need a graphic tablet (Wacom). The mouse is much less suitable as it is not pressure sensitive.

The Illustrator Brush Tool is widely neglected but it is really a very versatile and powerful tool. Here is a look at the Illustrator toolbox containing the paintbrush tool and my (customized) brushes palette:

paintbrush tool and brushes palette

To create brushstrokes in Adobe Illustrator, you simply select the paintbrush tool from the toolbox, select the desired brush type from the brushes palette and use the stylus to paint strokes on your graphic tablet. Illustrator will calculate an underlying vector path for the stroke with anchor points (Bézier points) in strategic spots as well as record the width information from the amount of pressure you apply while drawing your stroke. The brushstroke will be wider where you pressed hard and narrower where you let off.
Paintbrush work in Adobe Illustrator is extremely rewarding and forgiving since every single stroke you draw is a ‘live’ vector path that can be individually addressed and thus remains fully editable.

To edit the appearance of a brushstroke, make sure it is active (selected) and either:

- Retouch your stroke using the brush tool or pencil tool to change the curvature;
- Use the scissors tool to cut your stroke into smaller bits;
- Use the eraser tool to remove part(s) of your stroke;
- Adjust the width of your entire stroke by changing the numeric value;
- Change the appearance of your stroke by selecting a different brush type from the palette;
- Change the angle and other attributes of your brushstroke by editing the brush type presets;
- Adjust your stroke by pulling the Bézier handles on individual anchor points of the vector path;
- Scale, rotate, skew or free-transform your stroke into the desired shape.

Find some illustrations of these stroke-editing options below.

Should all of these options still fail to produce the perfect brushstroke for you, simply delete the entire stroke and paint a new one without disturbing any of the underlying artwork.

I do 95% of my ink-work with only one single brush. It is just a simple round brush with an 8 pt diameter. Double clicking its icon in the brushes palette produces the dialogue box for the brush-options or -presets.

brush-options for my main brush

Note that I have selected “pressure” in the stroke width field to accommodate for the pressure sensitivity of the graphic tablet. Also note that the width variation is relatively large at 8 pt, so 100% of the actual brush size.
With these options, you’ll be able to nicely control the width of your brushstrokes for doing digital ink-work or pinstriping on your graphic tablet.

In the example below, you see some sample brushstrokes with the above settings. I left the underlying vector paths selected so you can see what is going on underneath the outer appearance of the strokes.

A – Brushstroke drawn while applying little pressure;
B – Brushstroke drawn while applying more pressure;
C – Brushstroke drawn while applying increasing pressure from left to right;
D – Brushstroke C partly deleted (cut) using the Scissors tool;
E – Brushstroke C partly deleted (erased) using the Eraser tool.

sample vector paths – brushstrokes

To adjust the stroke width of an entire stroke, simply select the stroke and change the numerical value for the stroke width in the stroke-weight dialogue box.

editing the stroke width value of a brushstroke

In order to change the appearance of the brushstroke by applying a different brush type, make sure the stroke is selected and simply pick another brush type from the brushes palette. In the example below, different brush types are applied to duplicates of a stroke. Note that some brush types support the variable width from left to right while others do not.

applying different brush types to a stroke

To manipulate the curvature of a brushstroke, simply try retouching it with the brush tool or pencil tool. This is an extremely powerful option:

stroke manipulation by retouching

You can also manipulate or “steer” your stroke by adjusting the vector path by moving, deleting or adding anchor points and pulling Bézier handles like with any other shape you draw in Illustrator. In this way, a straight stroke can even be ‘massaged’ into a circular stroke, should you so wish; see image below. Again, I have left the vector paths and handles selected to give an idea of what is going on underneath the outer appearance of the strokes. Note that I have added an extra anchor point in the last step.

vector path manipulation

As with all vector objects, brushstrokes can be scaled, rotated, skewed or free-transformed. Note that there is a difference between A – scaling a brushstroke and include scaling the stroke-weight and B – scaling a brushstroke and exclude scaling the stroke-weight:

scaling brushstrokes

You’d almost say that the perfect ink-job is within anyone’s reach with so many options at your disposal to manipulate and retouch your brushstrokes, right? Illustrator brushwork indeed gives you unlimited opportunities to transform and experiment and do some trial and error.

There is a bit of a learning curve involved however: Brush behavior may seem erratic and awkward at first. But with a little practice you will pretty soon start to get the ‘hang’ of it. In time, you’ll really start to appreciate the Illustrator brushes: They allow you to work in a much more loose and freehand style than what you’re used to if you have done mostly pen-tool work. Should you rather rely on the trusty pen tool to draw your strokes or if you use a mouse instead of a graphic tablet, you can still assign brushstrokes to your paths but you do not have the additional feature of the variation in line widths. After all; mouse clicks are all recorded at an even ‘pressure’.

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