Should You Clean Your Coins? The Honest Answer
I cleaned a coin once. An 1880-S Morgan dollar that had a bit of gray toning I found unattractive. I used a product I found at a hardware store, carefully wiped it down, and turned what was probably a $90 coin into a $40 coin. The cleaning was visible under a loupe in about five seconds. That was the last coin I cleaned.
Why the Standard Advice Is "Never Clean"
The rule against cleaning numismatic coins exists because cleaning damages value in two compounding ways. First, any cleaning that involves rubbing or abrasion removes microscopic surface metal. Those flow lines that create luster — the thing that makes an uncirculated coin beautiful — are on the outermost layer of the coin. Wipe a coin with anything, even a soft cloth, and you break those lines. The result is called "hairlines" under a loupe: fine scratches that reflect light differently from the original surface. Grading services can spot cleaned coins almost immediately and will note them as "cleaned" or "whizzed" on the holder, which dramatically cuts resale value. Second, cleaning removes natural patina — the chemical changes that occur on a coin's surface over decades. On silver and copper, that patina is called toning, and it can range from ugly (blotchy brown patches that look like damage) to extraordinarily beautiful (rainbow toning around the rim of a Morgan dollar, gold-to-blue to purple shifting in the light). Toning that developed naturally over 100 years is irreversible. Once you remove it, you can't put it back, and the surface beneath is permanently altered. The market reflects this. Two Morgan dollars of identical strike quality and wear level — one with natural toning, one stripped clean — will not sell for the same price. The cleaned example sells at a significant discount, sometimes 30–50% depending on severity.The Specific Case for Careful Conservation
This is where the nuance comes in, and where experienced collectors part company with the blanket "never touch it" crowd. **Active corrosion is a different problem from dirt.** A copper coin developing active green verdigris is being chemically eaten. Leaving it alone guarantees it continues to deteriorate. Careful removal of active corrosion — using a product like MS70 Coin Cleaner, in a container, without rubbing — can halt the damage. The coin may still be considered "impaired" by grading services, but an impaired coin that's stable beats one that's still corroding. **Encrusted dirt on ancient or circulated coins** is a different category from the surface character of collectible modern coins. Archaeological coins pulled from excavations have dirt, soil, and mineral deposits that are genuinely foreign to the coin surface, not part of the original metal. Careful removal of that material under magnification with the right coin conservation tools is accepted practice in ancient coin collecting. **Non-numismatic coins** — coins you want to display but which have no collector value — can be cleaned however you like. A raw circulated clad quarter from 1995 has essentially no collector premium; cleaning it for display purposes harms no one.The Storage Argument Against Cleaning
The best argument against cleaning is that good storage prevents the problem. Toning and surface contamination develop when coins are exposed to reactive gases, humidity, and skin oils. A coin in a proper coin capsule or in a coin storage album with archival-quality pages doesn't tone the way a coin left loose in a drawer does. For copper coins specifically — which are the most sensitive to environmental exposure and the most common victims of amateur cleaning — individual coin holders made from inert materials keep the coin's surface character stable for decades. The investment in proper storage is almost always cheaper than the loss in value from a cleaning attempt. Cotton gloves when handling, airtight storage when not displaying, and a coin magnifier to inspect before buying are the three habits that eliminate most of the situations people try to clean their way out of.What I'd Skip
Skip vinegar, lemon juice, ammonia, and DIY cleaning solutions for any coin with collector value. These household acids work on some surface contamination but leave chemical residue that continues to react with the coin surface after treatment. They also strip patina indiscriminately. The MS70 and Blue Ribbon products mentioned in conservation literature exist because they were formulated specifically for metal chemistry — household alternatives aren't equivalent. Also skip the "I'll just give it a quick wipe" approach. There is no quick wipe that doesn't leave hairlines. Even distilled water dragged across a surface with a cotton ball creates micro-abrasion under sufficient magnification. **Bottom line:** Don't clean coins you intend to sell or that have numismatic value. Store them properly from the start. If you have a coin with active corrosion, research coin-specific conservation products and proceed carefully with the understanding that you're preserving stability, not original surfaces. Ready to shop? Compare Collecting & Hobbies across stores →📢 Affiliate Disclosure: This article contains affiliate links. We may earn a small commission at no extra cost to you when you click through and purchase.
