You might think, however, that perhaps tarnish can safely be removed in other ways. However, if any of the commercial cleaning methods demands rubbing with any kind of cloth, the answer is a loud NO for the same reason as above-even the softest cloth in the world can leave hairlines.
How about commercial solutions or "dips"? The answer is a very cautious "It depends." Inparticular, it depends on what active ingredients give the dips their effect, and these are not always listed on the label. Formerly, cyanide was one of the most popular, though among coin collectors the stuff began to lose a little of its reputation after 1916, when the illustrious J. Sanford Saltus picked up the wrong water glass while cleaning coins, and died a few seconds later, possibly without realizing that he had made a mistake. Cyanide lost the rest of its reputation a few decades later, after collectors heard that it acts by dissolving away the top layer of metal from the coins, dulling proofs with even brief use.
The dips that consist primarily of detergent mixtures may be safe for gold or nickel, but the effect on silver is likely to be an unnatural white color, and the effect on copper is an equally unnatural pale pink, which quickly retarnishes, depending on (among other things) how acid or alkaline they are, and how carelessly - if at all- they were rinsed off.
Those that derive their punch from thiourea require the same comment only more so, the color imparted to silver often being yellow or even chalky, and that imparted to copper or bronze looking like the bottom of a copper pot which has been scrubbed to remove burnt-on spills. Thiourea dips keep on working indefinitely long unless they are completely rinsed off, and they activate metal surfaces (as does cyanide), accelerating further tarnishing.
What is left? For gold or nickel proofs, get a covered dish of ammonia (either clear or cloudy will do - the cloudiness is from a detergent), put the coin in a tea strainer, dip it for a couple of seconds only, rinse immediately in hot running water, smell to make sure the last traces of ammonia are gone, air-dry; repeat only once if necessary. Whatever is unaffected by the ammonia dip will probably yield to a dip in methyl ethyl ketone (MEK).
Silver proofs may be given the MEK treatment. Ammonia is not recommended except in the emergency of black stains, against which it may not work anyway; the reason is that ammonia forms soluble complexes with the cuprous or cupric ions in the tarnished alloy, so that repeated ammonia dips leave an unnaturally white surface which-under a microscope shows thousands of minute rough streaks - irreversible damage. The stable golden and bluish tones should be left strictly alone, as they protect the coin against further atmospheric attack in the absence of grease or moisture.
We have as yet had no opportunity to test either the ultrasonic bath or the magnesium plate; these will be discussed in future editions.
There is no way for any amateur safely to remove spots or stains from copper proofs. Dulling is often associated with thin greasy films on copper or bronze; this will yield to MEK though with a certain risk of imparting a bluish color. A safer procedure is CARE, either as a dip (freshly poured only) or applied with a Q-tip and the excess removed the same way, using extreme care not to leave lint. Old CARE - even after only 5 to 10 minutes' exposure to air in a dish is not to be used, as the essential solvent has by then mostly evaporated, leaving mostly silicone, which has no effect except to retard access of atmospheric contaminants. Unfortunately, the stuff becomes sticky as it progressively dries, attracting lint.
If the above sounds a little intimidating, it is meant to; the only safe procedure for the beginner is to leave cleaning and restoration to experts. And some stains will deter even experts. The reason we do not recommend experimentation is that mistakes can be too costly even if you are not using cyanide. Beauty emphatically is skin deep on proof coins, and once it is gone, it does not come back.
Investment. As I write this the market is in a state of confusion the most recent auctions containing important offerings of proof coins failed to show any trend either up or down; within the same series, some coins brought world's record highs, other of the same quality sagged and slumped unpredictably. At present some gold proofs can be obtained less expensively than their twin sisters could be in 1974, which was one of the regular 100year peaks (years ending in 4 have long been notorious for brief peaks in coin prices), but others have gone into orbit, and there is not emergent pattern.
On the other hand, I am inclined to believe that -brief fluctuations aside -proof coins of any metal, for which either low mintage or high meltage can be proved, will be on a long term upward trend as long as people collect U.S. coins at all, especially as long as early proofs continue to remain the caviar and truffles and peacock's tongues of the series. I refuse to believe for a moment that interest could permanently disappear in a coin of which only a dozen are known, though the amount of market interest (the number of collectors, and their enthusiasm at any one time) will of course fluctuate with such factors as the momentary state of the stockmarket, the state of the economy generally, the number of specialists around at the time, the amount and type of publicity, the frequency with which any individual coin has been making the rounds among dealers, and for all I know the phase of the moon.
There is no way to Get Rich Quick in this field -otherwise instead of writing this book I would have been stashing every spare cent since 1950 into coins of this kind, and cashing in since 1974 - but there is a way to manage your collection rationally so that at the very worst the possessions which gave you a lot of fun over the years will have cost you little or nothing, but more likely you will have made more than you put in (including the cost of this and your other reference books), and quite possibly you will have made a tidy profit. The way is to familiarize yourself thoroughly with the rarity levels herein, with the price histories, and with the difference between ordinary cleaned proofs and the really pristine ones (which are the real blue chips), and be guided accordingly. As more people do this, the difference in price levels will become greater and greater, both proportionately and absolutely, to the benefit of those who were discriminating as to quality from the very outset.
There is, of course, no way to seek completeness in this field. Despite the fame of the Louis Eliasberg collection, even he never managed completeness of date-mintmark combinations: he never owned an 1841 O half eagle, a strawberry leaf cent, or an 1861 Paquet twenty, even aside from some overdates or certain of the restrike half-cents; and no other collection is anywhere close, even the Smithsonian's being weak in mintmarked silver coins. However, you can try for completeness in a given date (like Harry Boosel on 1873) or denomination, or for either first or last years for a given design, or you name it. Even brief issues like the capped bust half dimes 1829-37 will make very impressive displays, and they are as of this writing still undervalued compared to dimes or quarters of the same period. Smaller coins like trimes, nickel 3¢ pieces, or half dimes, have long been neglected compared to their larger brethren. I have the distinct impression that a collection organized around a theme or specialty is likely to perform better at auction than a collection of more haphazard kind in which a few rarities are imbedded; and certainly it will win more exhibit prizes at major conventions. Proofs with which original cases or mint wrappers or mint transmittal envelopes are included have a historical interest far in excess of their counterparts lacking such papers, and this too is likely to show up in the prices realized at auction. This is notoriously true of the 1938 Jefferson nickels on original presentation card (150 made) or of the 1903Jefferson or McKinley dollars; in original frames signed by mint officials testifying to their being among the first100 struck. In addition, coins provably traceable back to famous collections of the past, especially retaining the original papers and/or envelopes, acquire what Dr. Sheldon used to call "pedigree premium." Your own imagination and common sense can now probably enable you to figure out similar factors which can override the law of supply and demand, causing individual coins to perform better, or at least to show higher potential, than their sisters without such factors.
Walter Breen Albertson, N.Y. April, 1977