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<p>[QUOTE="7Jags, post: 4727841, member: 78719"]OK, I don't have a chart but taking it from the top:</p><p><br /></p><p>- Palladium and Platinum are pretty much immutable and therefor can use modest or strong acid or even organic solvents such as acetone or even rubbing alcohol.</p><p><br /></p><p>- Gold 0.900 and above (and possibly as low as 0.500, with lesser results as the fineness drops) will respond to oxidation of the alloys such as copper with reduction reactions. This would be the boiling water with aluminum foil placed in and then coin and baking soda. This will take off most dreaded red spots that is seen even on .999 fine coins. I showed this before on these boards with the 2014 Kennedy struck in 0.999 gold - it removed the spot with NO traces.</p><p>Note that this is NOT destructive to the host coin metal on 0.900 and above.</p><p><br /></p><p>I have not seen metal destruction to occur on several Franklin Mint 70s/80s vintage o.500 gold coins but I am not sure of the alloy metal mixed with the gold.</p><p>In any case, I have not seen pitting or other destruction to occur with this method.</p><p><br /></p><p><br /></p><p>One can use acidic solutions such as the common dips on gold as well, but they don't seem to address the red ("copper") spots as well.</p><p><br /></p><p>Detergents can remove gunk or dirt with liberal wash and tamp dry. Note rubbing gold may rather easily hairline the surface.</p><p><br /></p><p>Ammonia can be used on gold as well but one should make sure it doesn't have a bunch of coloring or aromatic agents in there as it can not be easily tested and as they say, results may vary.</p><p><br /></p><p>- Silver: ah, this is where it gets controversial. Reduction reactions can work like above. However higher voltage tricks with batteries which accelerate this reaction can be dangerous.</p><p><br /></p><p>Dips in moderation are treating the silver surface with acid and result over time or long exposure with potential loss of lustre on a microscopic level. However, they are used by many and with lesser and careful exposure can lead to decent results if not in excess. These have been employed many times when "blast white" pieces are encountered. Silver coins from the 19th C. and before should not ordinarily be "blast white " and 99% are indicative of a dip.</p><p>As a precautionary measure, all residue from the dip must be liberally washed or rinsed from the surface with as close to distilled water as possible. I generally wash with a mild detergent, THEN the water. With either method I tamp dry with a HIGH NAP WHITE COTTON TOWEL - this removes moisture and should not harm surface.</p><p><br /></p><p>Notum: this silver bit is occasionally tricky and I don't advocate its use by inexperienced.</p><p><br /></p><p>Detergents and warm water can remove surface debris on silver coins. Acetone OK - I tamp and not rub that on with Q-tip and then use rinse off technique like above.</p><p><br /></p><p>The other agents, like "Coinsolv", etc. can also sometimes remove gunk but IMO should be removed in a fashion similar to the dip mentioned above.</p><p><br /></p><p>Copper: I am not going there, way too dangerous.</p><p>However quick acetone usage like silver mentioned above is usually alright - I rinse as above. Prolonged exposure can alter metal surfaces on "red" specimens or "red brown" specimens (there is a time and temperature dependent slow chemical reaction even with this "inactive" solvent).</p><p>Detergents and water with rinse off like above. </p><p><br /></p><p>The other copper cleaning agents are hit and miss and will not elaborate except to say I occasionally use them with liberal detergent and rinsing...</p><p><br /></p><p>Anyway, I am out of breath and energy...Maybe we can revisit later....[/QUOTE]</p><p><br /></p>
[QUOTE="7Jags, post: 4727841, member: 78719"]OK, I don't have a chart but taking it from the top: - Palladium and Platinum are pretty much immutable and therefor can use modest or strong acid or even organic solvents such as acetone or even rubbing alcohol. - Gold 0.900 and above (and possibly as low as 0.500, with lesser results as the fineness drops) will respond to oxidation of the alloys such as copper with reduction reactions. This would be the boiling water with aluminum foil placed in and then coin and baking soda. This will take off most dreaded red spots that is seen even on .999 fine coins. I showed this before on these boards with the 2014 Kennedy struck in 0.999 gold - it removed the spot with NO traces. Note that this is NOT destructive to the host coin metal on 0.900 and above. I have not seen metal destruction to occur on several Franklin Mint 70s/80s vintage o.500 gold coins but I am not sure of the alloy metal mixed with the gold. In any case, I have not seen pitting or other destruction to occur with this method. One can use acidic solutions such as the common dips on gold as well, but they don't seem to address the red ("copper") spots as well. Detergents can remove gunk or dirt with liberal wash and tamp dry. Note rubbing gold may rather easily hairline the surface. Ammonia can be used on gold as well but one should make sure it doesn't have a bunch of coloring or aromatic agents in there as it can not be easily tested and as they say, results may vary. - Silver: ah, this is where it gets controversial. Reduction reactions can work like above. However higher voltage tricks with batteries which accelerate this reaction can be dangerous. Dips in moderation are treating the silver surface with acid and result over time or long exposure with potential loss of lustre on a microscopic level. However, they are used by many and with lesser and careful exposure can lead to decent results if not in excess. These have been employed many times when "blast white" pieces are encountered. Silver coins from the 19th C. and before should not ordinarily be "blast white " and 99% are indicative of a dip. As a precautionary measure, all residue from the dip must be liberally washed or rinsed from the surface with as close to distilled water as possible. I generally wash with a mild detergent, THEN the water. With either method I tamp dry with a HIGH NAP WHITE COTTON TOWEL - this removes moisture and should not harm surface. Notum: this silver bit is occasionally tricky and I don't advocate its use by inexperienced. Detergents and warm water can remove surface debris on silver coins. Acetone OK - I tamp and not rub that on with Q-tip and then use rinse off technique like above. The other agents, like "Coinsolv", etc. can also sometimes remove gunk but IMO should be removed in a fashion similar to the dip mentioned above. Copper: I am not going there, way too dangerous. However quick acetone usage like silver mentioned above is usually alright - I rinse as above. Prolonged exposure can alter metal surfaces on "red" specimens or "red brown" specimens (there is a time and temperature dependent slow chemical reaction even with this "inactive" solvent). Detergents and water with rinse off like above. The other copper cleaning agents are hit and miss and will not elaborate except to say I occasionally use them with liberal detergent and rinsing... Anyway, I am out of breath and energy...Maybe we can revisit later....[/QUOTE]
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