Storing & Handling Ancient Coins

Ancient coins are remarkably durable — they have, after all, already lasted millennia — but the way you store and handle them can either preserve that survival or quietly undo it. The good news is that proper care is cheap and simple. It comes down to handling them safely, keeping them in the right materials, controlling the air around them, and resisting the urge to 'improve' them.

Handle by the edge, over a soft surface

Always hold a coin by its edge, between thumb and forefinger, never touching the faces. Skin oils and acids etch surfaces over time, and a single fingerprint can become permanent. Handle coins over a soft towel or padded tray so a dropped coin lands gently — a hard floor can put a rim ding on a coin that nothing else has marked in two thousand years.

Get coins out of PVC

The single most common cause of self-inflicted damage is the wrong plastic. Soft, flexible flips and sleeves made with PVC slowly release chemicals that attack the coin, leaving a green, sticky residue — 'PVC contamination' — that disfigures surfaces. Store coins only in inert, archival materials: Mylar/PET flips, polyethylene or polypropylene holders, hard plastic capsules, or certified slabs. If a holder is soft and smells faintly of plastic, get the coin out of it.

• Use inert holders: Mylar/PET, polyethylene, polypropylene, or hard capsules.
• Avoid soft, flexible PVC flips entirely.
• Slabs (NGC Ancients) are inert and ideal for long-term storage.

Bronze disease: the one real emergency

Bronze disease is an active chloride corrosion that appears as powdery, light-green spots and can spread, eating a bronze coin over time. It is driven by humidity, so prevention is dryness: store coins in a stable, low-humidity environment with silica-gel desiccant, away from basements and attics. If you ever see fresh, powdery green growth that wasn't there before, isolate that coin from the rest of the collection and seek conservation advice — untreated, it can destroy the coin and potentially affect neighbours.

Never clean a patina

The hardest rule for beginners: leave the surface alone. The smooth green or brown patina on a bronze, and the toning on silver, are the coin's natural protective skin and a large part of its value and beauty. Harsh cleaning — acids, abrasives, even vigorous rubbing — strips that skin, leaves a coin bright, raw, and 'cleaned-looking', and permanently reduces its worth. A light rinse in distilled water and a gentle pat dry is the most any collector should do. When in doubt, do nothing; an honest old coin is always better than a damaged shiny one.