Hello, this is the tutorial using opacity mask, like the title said. Using this mask, you could have a more complicated mask , and I think this is an awesome trick to learn. Let’s get it done then….
Make box using rectangle tool(M), then go to window>swatch library>gradients>sky. Fill it without any stroke. And we just made our base color.
Next, go to window>symbol>grime vector pack. Select symbol sprayer tool (shift+S) and then spray it once.
Select the sprayed item, go to object>expand. Click ok.
And then recolor it into white. Drag it into the symbol box(shift+ctrl+F11).Name it anything you want.
Now back to our base color. Go to transparency box (shift+ctrl+F10). Click the drop down icon, select make opacity mask. It should look like this now.
Activate the black one, select symbol sprayer tool (shift+S), and choose the one we just made.
Spray it a couple of times. You could get a variation using other symbol tool.
Then go to object>expand, then click break link in the group box.
Select twirl tool in the tool box. Start twirl it, until you like the result. This is how mine’s look like.
I know it just a short tutorial but using this method and the radiance method I could get result like this.