is 'additive free' washing up detergent. Mix with luke warm water and then clean the chips with an old soft toothbrush. Do not immerse the chip in the water - use the toothbrush to just pick up a few soap suds and then use it. Very quickly hold the chip under running cold running water to remove any final trace and dry immediately with paper tissue. If it is a hot stamp chip then keep your thumb over the foil when cleaning - else the gold may turn silver.

However...I clean only a few more chips than Gene (which is approximately zero). As Archie always says - cleaning does not increase the value!