The Environmental Enemies
Coins are under constant attack from invisible environmental threats. Understanding these enemies is the first step to protecting your collection.
Humidity
Moisture causes corrosion on copper (verdigris), toning acceleration on silver, and spotting on all metals. Keep humidity between 30–50%. Use silica gel packets in storage areas.
PVC (Polyvinyl Chloride)
Soft vinyl coin flips contain PVC plasticizers that leach onto coin surfaces, creating a green, oily residue that etches into the metal. Never use soft vinyl flips for long-term storage. Use only Mylar (non-PVC) flips, cardboard holders, or hard plastic capsules.
Sulfur
Sulfur compounds (from rubber bands, certain papers, cardboard, and air pollution) cause silver coins to tone. While some toning is attractive, uncontrolled toning from rubber bands or low-quality storage materials creates ugly, dark discoloration.
Temperature
Temperature fluctuations cause condensation. Store coins in a climate-controlled environment — avoid attics, basements, and garages.
Handling
Fingerprints contain acids and oils that permanently etch coin surfaces. Always hold coins by the edges over a soft surface. Wear cotton or nitrile gloves for valuable coins.
Up Next
This guide is for educational purposes. Where official standards, grading services, organization memberships, or legal requirements apply, consult the primary authority named in the references below or the relevant government agency.
Reviewed on January 10, 2026 by the US Coin Shows editorial team. Editorial policy
Frequently Asked Questions
What damages coins in storage?
Humidity (corrosion), PVC from soft vinyl flips (green residue), sulfur from rubber bands and cardboard (ugly toning), temperature fluctuations (condensation), and fingerprint oils (permanent etching).
What is PVC damage on coins?
PVC plasticizers from soft vinyl flips leach onto coins creating a green, oily residue that etches the metal. Never use soft vinyl flips for long-term storage.
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