If you have old pre-clad coins of numistic value you may ruin this value by over cleaning and damaging them, so be careful.
Re: Buy a cheap tumbler!
http://www.findmall.com/read.php?19,851193
Re: Cleaning Coins
http://www.findmall.com/read.php?63,853165
Cleaning coins!
http://www.findmall.com/read.php?55,887697
"First try a distilled water soak and a soft makeup brush.. After that (if needed) hot hydrogen peroxide (heat up in the microwave or a coffeemaker hot plate and place coin in, check every 1/2 hour and change the solution when it stops fizzing, remove crud with a soft brush and running water... Or make instant potatoes and place the coin into them.. Check every half hour and as with the rest clean with a soft brush and running water.. After cleaning a soak in distilled water for a day and when dried soak in a preservative like coin wax,beeswax or Vaseline.. Just go slow and always keep a eye on the progress,as always, to little is better than to much.. I hope this helps..."