Try to find pads called ScotchBrite, about 1/4" (7mm) thick and looks like real dense furnace filter. They come in red, green or gray depending on the courseness rating. Most hardware stores will carry it.

These are couple of good cg calc. sites
http://www.palosrc.com/instructors/cg.htm

http://www.lvrcs.com/content/index.php