Which questions about coin cleaning and the 1-70 grading scale will I answer - and why they matter?
You hold an old coin and someone told you that rubbing it with a cloth or a certified coin dealer reviews kitchen cleaner destroys half its value. That blanket statement is partly true, partly wrong, and very dangerous advice if you want to protect a coin's worth. This article answers the practical questions collectors and sellers actually ask: what the 1-70 grading scale means, how cleaning affects different grades, when cleaning is catastrophic, when it might be salvageable, and what to do now if you've already touched a coin. Each question matters because a single misstep can mean losing thousands of dollars on a rare piece or throwing away the chance to sell even a common coin cleanly to a buyer.
What does the 1-70 coin grading scale actually mean and why does MS60+ matter?
The 1-70 scale is a numeric system used by major grading services to describe a coin's condition from heavily worn and damaged to perfect. It breaks down roughly like this:
- 1-59: Circulated grades. These coins show wear, ranging from barely visible design details to extreme smoothing. Subclasses include Good, Fine, Very Fine, Extremely Fine, About Uncirculated (AU). 60-70: Mint State (MS). These are uncirculated coins - they received no intentional circulation after leaving the mint. MS60 is an uncirculated coin with obvious contact marks, heavy bag marks, or poor strike. MS70 is flawless under 5x magnification.
Why MS60+ matters: Numismatists and buyers attach big premiums to coins that are mint state because uncirculated coins are rare relative to circulated survivors, and their surfaces are original. Within MS grades, small differences matter: MS63 versus MS65 can be thousands of dollars on certain issues. That sensitivity explains why surface quality - including whether a coin was cleaned - can dramatically change market value.
Does cleaning a coin always destroy 50% of its value?
No. Saying cleaning cuts value by 50% is an oversimplified myth. The real effect depends on three factors: the coin's rarity, the type and aggressiveness of the cleaning, and whether the original surface or toning is part of what collectors prize for that issue.
- Rarity: Extremely rare coins often retain substantial value even when improperly cleaned. A one-of-a-kind error piece will still draw collectors, though it will sell at a discount compared with an unaltered example. Degree of cleaning: Light, non-abrasive rinses or removal of sticky residue can sometimes be invisible to graders. Heavy abrasion, acid baths, or polishing produces hairlines and altered luster that are easy to spot. Grading services will often assign a "details" grade and note "cleaned" or "improperly cleaned," which removes the coin from the market for numerical grading and cuts its pool of buyers. Market taste: Toning - the natural color that forms on silver and copper over time - often adds desirability. Removing attractive toning reduces value far more than wiping off grimy dirt would.
Example scenarios:
- A common date circulated Lincoln cent that you lightly scrubbed with dish soap might only lose saleability to collectors but still have similar scrap or face value. Many dealers will buy it as a cleaned common. A fully struck MS65 Morgan dollar that you polished with a jeweler's cloth could lose tens of percent because the polish removes original mint luster and creates hairlines. Grading services will flag the surfaces. A unique early copper coin cleaned decades ago may still sell for tens of thousands because collectors seek the rarity despite the cleaning - but expect a significant discount.
How should I clean or conserve an old coin without hurting its value?
Short answer: most of the time, don't clean at all. If you must intervene because of corrosive material or active deterioration, follow conservative steps and get professional help for anything of real value.
Practical step-by-step guidance
Stop and assess. Is the coin valuable? Quick search of the type, date, mint mark, and condition on price guides or auction sites will tell you if it's worth professional attention. If it might be worth more than a modest fee, do not clean it yourself. Handle properly. Use cotton gloves or hold by the rim. Oils from your fingers cause smudges that are sometimes mistaken for cleaning or damage. If the coin has sticky residue or dirt that risks further damage, try a gentle distilled water soak. Use a small container, place the coin in distilled water at room temperature for 24-48 hours, then gently blot dry with lint-free paper. No rubbing. Use acetone only for organic residues like tape adhesive. Pure acetone (nail polish remover often contains additives, so avoid that) will remove organic grime and evaporates cleanly. Do this in a ventilated area, with gloves, and brief exposure. Do not use on porous problems and do not scrub while in acetone. Avoid olive oil, vinegar, baking soda, toothpaste, or abrasives. Olive oil soak is a long-term hobby method but can darken surfaces and leave residues hard to remove. Acids and abrasives permanently alter the metal surface and are the fastest way to destroy value. When in doubt, consult a trusted dealer or conservation specialist. Professional conservation can stabilize a coin and sometimes restore marketability without altering original surfaces, but it costs money - which is worth it for high-value items.When is cleaning acceptable, and when is it catastrophic?
Acceptable cleaning is strict and rare. If a coin sits in a storage environment causing active corrosion - like verdigris on copper or bronzing that puffs up the surface - stabilizing it is justified to stop further loss. That should be done by a professional who documents the process. Catastrophic cleaning is anything that changes the surface texture, removes mint luster, or strips patina that formed naturally over decades. Those changes are permanent.
Real-world examples:
- Acceptable: A saltwater-flooded coin with active chloride corrosion. Conservators can remove chlorides and apply desalination techniques to prevent further damage. The coin may still show evidence of exposure but is stabilized and sellable. Catastrophic: Polishing a Morgan dollar to 'shine up' the design. Polishing creates fine circular hairlines and flattens the original satin or cartwheel luster - graders flag the coin and its numerical grade is usually withheld.
How do grading services handle cleaned coins and what does a "Details" grade mean?
Major third-party grading companies authenticate and grade coins but will annotate issues that affect surface originality. If a coin shows evidence of cleaning, the company will often provide an attribution like "Net Cleaned" or "Improperly Cleaned" on the holder and will give a "details" grade rather than a straight MS/XF number. That label signals to collectors the surface is altered and usually reduces the numismatic value dramatically.
Key points about "details" grades:
- "Details" means the coin has been authenticated and described; it is not given a collectible numeric grade because the surface isn't original. Some cleaned coins still hold value. If the coin is rare enough, buyers will accept a "details-cleaned" holder but pay a discount relative to an uncleaned piece. Documentation matters. If a coin has a documented conservation history from a known lab, buyers are more comfortable than when a coin shows unknown amateur intervention.
Should I try to sell a cleaned coin, declare cleaning history, or hide it?
Always disclose. Hiding a coin's cleaning history is unethical and will ruin buyer trust. Disclosing a cleaned surface reduces legal risk and builds reputation. Many markets accept cleaned coins at discounts, and some buyers prefer them, but transparency is essential.
How to approach selling:
- List the coin as "cleaned" if you know it was cleaned. If you are unsure but see signs like hairlines or unnatural brightness, disclose those observations. Provide high-resolution photos showing surfaces at different angles under natural light. TPG holders or conservation reports increase buyer confidence. Price to attract buyers given the cleaning. Research completed auction results for "details-cleaned" examples to set expectations.
When does an MS60+ grading still make a coin collectible even after cleaning?
MS60+ indicates uncirculated surfaces originally. If a cleaned coin is sent to a grading service, it will likely not receive an MS grade if the surfaces are altered. But there are circumstances where an originally MS coin remains collectible:
- Rarity trumps surface. Extremely scarce dates or mint errors draw collector interest despite cleaning. Their market price reflects rarity more than surface quality. Partial cleaning with minimal evidence. If the intervention removed only loose debris and left original luster intact, a slabbed MS coin might still result from grading, though that outcome is rare. Conserved coins with documentation. A coin that received professional, reversible conservation and a lab report can maintain investor interest, especially if the conservation was aimed at stabilization rather than aesthetic improvement.
Example: A rare Proof-19th-century pattern coin with slight residue might have been soaked in acetone by a professional conservator to remove glue from a paper tag. If that treatment didn't alter the metal, it might still receive a high MS or Proof grade when slabbed. Contrast that with hobbyist polishing, which is easy to detect and almost always fatal for a numerical grade.
What should I do now if I already cleaned an important coin by mistake?
Take a measured approach to salvage both the coin and your options:
Stop any further cleaning immediately. No more scrubbing, acid, or home remedies. Document what you did. Timeframes, materials used, and photos before and after if available will help a conservator assess damage. Contact a reputable numismatic conservator or an experienced dealer for an evaluation. Provide full disclosure of your actions. Consider professional conservation if the coin is valuable. It can stabilize corrosion or remove harmful residues without further altering the surface if done properly. If conservation is too costly relative to coin value, sell it as-is with full disclosure. Some collectors buy cleaned coins for study or for pieces where originality is less critical.How are grading standards and market attitudes changing, and what should coin owners watch for next?
Market dynamics are shifting toward a stronger premium for originality and provenance. Collectors now value untouched surfaces, attractive natural toning, and documented ownership. Grading services keep improving imaging and detection techniques for cleaning and alterations, so amateur cleaning that passed in the past is increasingly detectable. That raises the stakes for preservation today.
Trends to watch:
- Better detection: Advanced imaging and spectral analysis mean subtle changes are easier to spot. Don’t assume that a small polish will go unnoticed. Documentation matters: Provenance, old sales receipts, and professional conservation reports add value and buyer confidence. Toning appreciation: Natural, attractive toning continues to attract a premium in many collecting niches. Do not remove toning because you think buyers prefer 'bright' coins. Specialized markets: Certain collectors and dealers focus on raw or specially conserved coins. If you have a cleaned coin, research niche buyers who will pay more than scrap or melt value.
Final, practical protections
- If you only have inexpensive common-date circulated coins, brief, careful cleaning will seldom ruin value drastically but avoid abrasive scrubbing. For any suspect valuable coin, stop and get expert advice. Use protective storage and avoid humid or acidic environments that cause active corrosion. Prevention is far cheaper and less risky than any restoration attempt. When in doubt, disclose. Buyers respect transparency and will often pay a fair price for a known-cleaned coin rather than being surprised by a hidden defect.
Bottom line: cleaning does not automatically mean a 50% loss, but it often means a meaningful discount, especially for mint state coins where surface originality is everything. Treat coins as fragile historical objects: preserve original surfaces, stabilize active damage professionally, and be transparent when selling. That approach keeps value and trust intact.