Recently a reader wrote about receiving “Details: Cleaned” grades from NGC, hoping to get more information about what constitutes a cleaned coin so that she can understand why seemingly unaltered coins are returned without grades.
She writes, “Of the last set of coins I sent to NGC, half came back ungraded due to having been improperly cleaned. Luckily, I learned from my first experience and instructed them not to slab if the coin was judged to have been cleaned. But because of my sensitivity to the issue, I took each of these coins to my lab (I’m a scientist) and examined them under the microscope to look for any change in luster and any pattern of small scratches, BEFORE I sent them in.”
The Morgans dollars, she added, had the full cartwheel reflection. “I cannot imagine what the grader was looking at; I can only assume that I need to learn more about grading. Or do I? Should I resubmit to PCGS? I’d hate to do this without figuring out if I missed something when examining the coins myself.”
I promised to dedicate a column to cleaning. Some pointers are listed below. Click on any image for an expanded version.
1. You should never clean coins. Conservation techniques, as practiced by NGC’s sister company, Numismatic Conservation Services, are beyond the scope of this post. There are special chemicals and chemical mixes that remove grime and PVC poisoning (a green residue that taints coins in pliable plastic flips containing polyvinyl chloride). We won’t share the chemical-mix recipes or over-the-counter products because more coins have been destroyed by hobbyists than ever have been conserved.
2. Distinguish slide marks from hairlines. Slide marks (caused by coins being removed and put back in albums containing plastic covers) sometimes are confused with hairlines caused by improper cleaning. (To bone up on slide marks, click here.) Bank-bag and stray marks can occur naturally due to circulation. Ones caused by cleaning are somewhat obvious because they leave tell-tale abrasive marks on the surface of a coin.
3. Be able to identify “almost uncirculated” coins from cleaned ones. “Slider coins”–ones that look uncirculated but really grade almost uncirculated (AU50-58)–often are rejected by grading companies as “cleaned,” when they just have traces of wear. Whereas slide marks (see #1 above) are almost uniformly straight up and down the length of a coin, almost uncirculated coins can have bag marks running in several directions, resembling improper cleaning. The keys to telling one from the other concern (a) an absence of abrasive hairlines deeper than circulation marks and (b) a uniform amount of luster remaining on the coin’s surface. If there are no rubs on a lustrous surface, it’s probably an AU coin. But again, we’re in the realm of judgment calls.
4. Know when a coin has been dipped. There are several coin brightening solutions that can actually enhance the appearance of a coin if done expertly. But more coins have been destroyed by dipping a coin in such a solution longer than necessary, without washing off the chemical adequately. Those coins have a grainy appearance with a washed-out look, easily discernible from uncirculated coins with cartwheel luster.
4. Identify cabinet rubs. Coins stored in boxes or drawers without protective flips or holders often slide on the wood, causing streaks. These are grade-worthy coins but often dubbed as cleaned. This 1879-S rev. of 78 graded MS63 by ICG failed to cross over to PCGS because of a such a rub on the cheek. I agree with PCGS, which graded the coin AU58.
5. Some coins are obviously cleaned … with scouring pads (Brillo). Here’s an example. These coins usually are destroyed, unless they are key dates, in which case, you can often buy them at 50% discount. Hobbyists know that one person’s tomfoolery (cleaning an 1893-S Morgan with Brillo) can be another person’s treasured key date coin completing a set.
Keep in mind when evaluating coins for cleaning, that some may have a trace of dip or rub and can go either way. If you use a loupe, you may be able to see hairlines caused by abrasives. Or you may see traces of grain caused by dipping solution. These, again, are judgment calls. When you feel sure that a holdering company has made a mistake, submit the coin to a competitor. You just might get a grade.