Many here have heard my philosophy on this subject before. My feeling is that I clean my chips lightly to take the loose dirt and crud off of them. Like fine antiques though, if you have ever watched Antiques Roadshow etc., I do not deep clean the chips. If there is a darkening or deepening in the color of a chip I do not want to disturb that. You do not want to do anything that might damage the finish or design. That is, check your chips carefully to see how they are printed. If gold hot stamped or painted you do not want to remove that. Some chips have paper apliques that can be damaged also. Be careful. If there isn't any paint but there is an engraving or embossing on the chip you may want to clean in a way that works dirt into or around the markings and cleaning only the top surface. This will add contrast and will make certain printings more readable. I often take tokens and simply buff them on a FLAT surface which cleans just enough to make the engraving or embossings stand out.

I, personally, use a mild soap. I do not apply anything directly on the chip or token though. I apply the cleaner to a soft cloth or my hands and rub around in a light, sort of circular, motion. Then I rinse and lightly dry. With tokens I use a product called MAAS. It is a paste cleaner. It is the same thing as other products like Simicrhrome and some other metal polishes. Use only the tiniest amount on a cloth and buff lightly. Wash in warm water and dry. Like I said though, I do not want to clean too deep and remove all of the aging.

Another consideration that you might keep in mind. What is the nature of the chip or token. Is it one that you collected because it is old and you like it's charm and rarity? If so, do not clean it as you will be removing a lot of that charm and making it look new. On the other hand, if it is a current chip that is in current use you might want it to look as though it is new if it is in good condition. Also think of the cheracter of the design and ask yourself if it adds to it's design to look old. An example that I often use is the Treasure Island $1 slot tokens. They have an appearance that resembles pirate gold. They actually look better, in my opinion, when they are marked up with bag marks and have an older aged patina. Remember that darkening, especially with metal, does not necessarily mean dirty. Some materials naturally darken and get richer in color with age.