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<p>[QUOTE=&quot;stldanceartist, post: 1213802, member: 13307&quot;]Interesting post in another forum from Mark Feld, a San Diego-area dealer and former NGC grader:</p><p><br /></p><p><span style="color: #000000"><font face="Arial">Treatments that merely remove adherent contaminants such as dirt, dust, debris, oil, PVC, or films of foreign substances without altering the underlying metallic surfaces of the coin are not doctoring. This category of treatments typically includes solvent dipping (such as acetone or isopropanol), and mild ultrasonic cleaning in an aqueous solution that does NOT contain reactive agents. Non-reactive agents include simple pH-neutral detergents and surfactants.</font></span></p><p><span style="color: #000000"><font face="Arial"><br /></font></span></p><p><span style="color: #000000"><font face="Arial">Any treatment that mechanically alters the surfaces (whizzing, brushing, abrading, polishing, electropolishing, lasering), or that alters the surface chemistry (deliberate removal or creation of oxides or sulfides by thermal and/or chemical processes) is DOCTORING.</font></span></p><p><span style="color: #000000"><font face="Arial"><br /></font></span></p><p><span style="color: #000000"><font face="Arial">Contrary to what has been stated in a previous thread on these boards, MS70 is NOT a harmless (i.e. non-reactive) detergent. A simple pH analysis shows it to be strongly caustic (alkaline). Further analysis indicates that in addition to any detergent or surfactant present in MS70, IMHO there is a presence of sodium hydroxide (caustic soda, the active ingredient in lye). Copper is fairly reactive with most acidic and alkaline agents. The sodium hydroxide that I believe to be present in MS70 will have a color-changing and surface-altering effect on copper.</font></span></p><p><span style="color: #000000"><font face="Arial"><br /></font></span></p><p><span style="color: #000000"><font face="Arial">Similarly, another household product that contains an alkaline hydroxide compound is well known to have color-changing effects on copper: namely, household &quot;ammonia&quot; (actually that is a misnomer; the common household product is not true ammonia, but rather an aqueous solution of ammonium hydroxide).</font></span></p><p><span style="color: #000000"><font face="Arial"><br /></font></span></p><p><span style="color: #000000"><font face="Arial">The use of MS70 or ammonia on copper falls squarely into the category of DOCTORING, as these hydroxide compounds are reactive with copper, and have an effect on surface chemistry and color. The effects are heightened at elevated temperatures.</font></span></p><p><span style="color: #000000"><font face="Arial"><br /></font></span></p><p><span style="color: #000000"><font face="Arial">The mere removal of a shellac film with an otherwise non-reactive agent such as acetone is not doctoring in my opinion. However, the recent surge of blue and other toned copper does not have its origin in the removal of old shellac coatings ... rather, it is being created by DOCTORING, including the use of ammonium and sodium hydroxides, and thermal treatments.&quot;</font></span><span style="color: #000000"><font face="Arial"></font></span></p><p><span style="color: #000000"><font face="Arial"></font></span>[/QUOTE]</p><p><br /></p>

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