theory11 — Magic Tricks & the World's Finest Playing Cards

Roughing Fluid

Yep, that worked for me. Make sure you spray them with the card propped up, maybe leaning on a card board box or something. You just spray from the top down, like spray paint.
 
Oh and one more thing. I'm double posting to make sure you see this. Be careful not to inhale it to much, not good for your lungs.
 
If you can, spray it on outside on a nice calm sunny day, you know those ones, usually had in summertime. Make sure its not windy though.

HAHA :D