I'll try to explain better. I actually lay the brush down on my counter, over a tissue or something, and then just rub the s/s over the bristles of the brush, like I'm coloring it. Shadestick on brush, not brush on shadestick. That's how the color gets on there...I get a decent color payoff, but it's not as vibrant as putting on the shadestick directly. What I do find that it does better is not tugging, and is a sheerer wash of color.
Definitely not necessary if you're using shadestick as a base, but if you want to use it as color, this works for me. HTHs!