Here are the directions on how to do this technqiue:
Rock N Roll
Matte cardstock light colored
Bold imaged stamps of your choice
Two color values of ink pads that compliment each other
Ink image in the lightest color value first. DO NOT STAMP!
Now roll the edges of the inked stamp onto the complimenting color of stamp pad. NOW STAMP ONTO CARDSTOCK!
Wipe stamp off and repeat as necessary to get the look you want to achieve.
You can wipe your ink pad off with a paper towel if you get too much of the other color onto it. This technique will not hurt your ink pads. I do it all the time. As long as you wipe the ink off the ink pad if it gets too messy you will be fine.