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<p>[QUOTE=&quot;desertgem, post: 1218666, member: 15199&quot;]Both erasers and toothpaste has abrasive components to do their job,They should not be used on coins where judgment on the originality of the surface is very important. This is especially true on modern coins as cleaning was known for causing damage during this age. For older coins, cleaning was often practiced and even taught as good procedure by many coin collectors, but the top collectors knew not to do so.</p><p><br /></p><p>There are products ( mentioned above) that can remove <b>SOME&nbsp; dirt/grime&nbsp; </b>with careful use, but the problem is that often the users of them do not take the time to learn their ability and limits. Acetone, Xylene, Pure water, Verdi-care, generally will be safe, but extended use, contaminated chemical and tools, and especially the knowledge to know when the coin can not be further conserved , or to know that the problem can not be improved without visible damage will occur. When I say visible, I mean for an experienced, impartial observer with a 5+ quality magnifier. Often the owner can not see the scratches from sodium bicarbonate or a soft brush, but they usually are there.</p><p><br /></p><p>If one uses any appliance, ( soft brush, toothpick, thorn, plastic dental pick, etc). The first time they not leave a scratch, but during that first time the appliance picks up dust or grit. Most of which is quartz with a Moh hardness of 7. The harness of copper silver and gold are about Moh hardness of 3, a factor of 4 magnitudes which is approximately 10,000 ( Moh hardness isn&#039;t as accurate as Vickers or Brinell, but close enough for examples. The the second use of a soft brush could be primed with a &quot;cutter substance&quot; many times harder than the surface, and the scratch gets larger.</p><p><br /></p><p>You should be able to tell PVC from verdigris</p><p>Able and knowledgeable to use hazardous chemicals</p><p>Strongly suspect from experience what will be under something you wish to remove. It may be worse than appearance.</p><p>Know a natural patina from one over treated chemically such as with an acid</p><p>Have an idea how dirt/grime/corrosion normally accumulates on the coins, especially in lettering and date.</p><p>and probably many more things.&nbsp; </p><p><br /></p><p>How do you learn? Experience is the main way. When I was evaluating BadThads products, I used over&nbsp; 100 different copper cents of various ages to see if color shifts occurred when over extended, how much verdigris could be expected to be removed, etc. Things only your eyes and experience can come to utilize. </p><p><br /></p><p>My 2 cents.</p><p><br /></p><p>Jim[/QUOTE]</p><p><br /></p>

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