Deke's Techniques 510: Applying Knockout Group to a Dynamic Path in Illustrator

In this week's free Deke's Techniques episode, Deke takes the powerful atomic symbol he dynamically drew in Illustrator last week and figures out how to make those electrons hollow so they reveal the background behind them.

You might think he'd already done that looking at where we left off last week:

A rotated red atom drawn dynamically in Adobe Illustrator

But, in fact, those "hollow" electrons are actually just filled with the background color. Fine if your background is a solid color, but the minute you change it:

The electrons are still red when you move to a new background.

And while I think the red electrons look cool, Deke and the incomparable Illustrator intellect Mordy Golding got to talking about the puzzle and, being the guys they are, had to solve it.

The answer was hidden in the Opacity setting of the Appearance panel, where a Knockout Group checkbox resides:

The Knockout Group checkbox resides in the Opacity area of the Appearance panel.

And after a few more adjustments (namely involving reducing the fill opacity settings of the circles that live inside the electrons), we finally arrive at Deke's desired goal:

The authentically transparent electrons now reveal their true background.

Thing is, Deke and Mordy, being the inquisitive Illustrator instructors they are, gave themselves yet another challenge: how to apply a drop shadow effect to the entire symbol (including the inside of the now-hollowed-out electrons).

If you're a member of, Deke's got an exclusive movie this week in which he (and Mordy) finally figure the puzzle out using Illustrator's Rasterize effect.

The Rasterize effect in Illustrator allows you to get that drop shadow inside the electrons.

If you're not a member of, and you want nothing more than to hear the saga of a couple of Illustrator nerds work out a problem, then you can get a free 10-day trial by heading to

Deke's Techniques, bringing illumination to Illustrator geeks and those who love them!



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