Brian,
I use a soft toothbrush & fantastik. I spray both sides of the chip & clean the dirt off with the toothbrush & then rinse under warm water. I dry the chip with a paper towel. I then use a VERY small amount of mineral oil (which brings out the true colors of the chip which may have been lost over time or due to cleaning) rubbed between two fingers & work it into the chip. That entire process should not take more than a minute. I'll then let the chip dry for 24 hours on one side & turn it over & let dry for another 24 hours before storing the chip. Andy - Las Vegas