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<p>[QUOTE=&quot;cladking, post: 1303650, member: 68&quot;]I avoid talking about US coins in this forum and it&#039;s difficult to provide a comprehensive answer without doing so.</p><p><br /></p><p>US mint packaging material since 1955 earns a solid B+ which is excellent by world standards.&nbsp; Many mints issue their&nbsp; coins in packaging which will simply destroy the coins in a few years.&nbsp; Try finding a nice 1975 Japanese mint set if you don&#039;t believe it.&nbsp; Most mints have been making improvements in recent years though and most new packaging should stand up to the long term (I believe).&nbsp; </p><p><br /></p><p>It appears that the PVC in the &#039;68 to &#039;84 mint sets was used to help bond the outer layers of pliofilm together.&nbsp; It is on both insides of the pliofilm.&nbsp; It is extraordinarily thin. It is so thin that very little &quot;green residue&quot; is generated.&nbsp; Indeed, I&#039;ve never actually seen the green but it is enough to attact the surfaces.&nbsp; Damage is very negligible at first and soaking it off in acetone (depending on denomination) will probably suffice to saving the&nbsp; coin.&nbsp; But if left on long enough the coin will pass from hazed, to mottled, to very light corrosion, to being destroyed. </p><p><br /></p><p>For denominations that are best treated with acetone they will need to be left in for 5 minutes to four days dependent on the severity of the problem.&nbsp; I find rinsing in warm water more effective at returning these to pristine condition.&nbsp; Some denominations are best treated with isopropyl (91% only!!) or denatured alcohol.&nbsp; Whatever mixture is used water should be strongly avoided.&nbsp; </p><p><br /></p><p>Put the still wet coins on a soft absorbant towel and pat dry very carefully.&nbsp; Try your procedure with junk coins first to be sure you are doing it properly.&nbsp; Look for hairlines on the coins with a 20x glass.[/QUOTE]</p><p><br /></p>

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