Key takeaways
- Trading cards are printed paper and card stock, so archival guidance for papers and photographs is a sensible guide for storing them.
- The US National Archives recommends sleeves of stable plastics, polyester, polypropylene or polyethylene, and lists unknown plastics and PVC among materials to avoid.
- Keep storage below 75°F, with relative humidity below 65% to prevent mould but above 15% to avoid brittleness.
- Store cards flat or upright in containers big enough not to bend them, away from pipes, windows, roof leaks, food and water.
- Handle cards by the edges with clean hands, and keep rubber bands, paper clips and adhesive notes off them.
To store trading cards so they last, put each card in a sleeve made of a stable plastic such as polypropylene, add a rigid holder for cards that must not bend, and keep the box somewhere below 75°F with relative humidity between about 15% and 65%, away from pipes, windows and food. Those figures and materials come from the US National Archives' guidance for family papers and photographs; trading cards are printed paper and card stock, so this guide applies that advice to a card collection.
Why archival advice applies
The National Archives' guidance for family papers and photographs describes the risks that matter for printed paper: warmth speeds chemical decay and insect activity, damp allows mould, very dry air causes brittleness, and some plastics and adhesives damage what they touch. It does not mention trading cards, so treat it as the closest authoritative guide rather than card-specific rules.
Choosing sleeves and holders
Start with the plastic that touches the card. The National Archives recommends sleeves of stable plastics: polyester, polypropylene or polyethylene, and lists unknown plastics and polyvinyl chloride (PVC) among materials to avoid, illustrated with an unstable plastic sheet that has become wavy and discoloured. Its guidance for photographs likewise says not to use plastics containing PVC.
| Layer | Purpose | What to look for |
|---|---|---|
| Soft sleeve | Protects the surface from scratches and fingerprints | Polypropylene or polyethylene, labelled PVC-free |
| Rigid holder or toploader | Stops bending | A stable plastic, sized so the sleeved card fits without force |
| Box or binder | Keeps cards together and out of light | Acid-free board for boxes; stable plastic pages for binders |
The Archives also notes sleeves should be larger than the original, because any part sticking out is likely to be damaged, and that only one item should go in each sleeve.
Storage conditions
The National Archives gives clear numbers:
- Temperature: below 75°F. The lower the temperature, the longer items last, because cooler conditions slow chemical decay and reduce insect activity.
- Relative humidity: below 65%, to prevent mould and reduce insect activity.
- But not too dry: below about 15% relative humidity can cause brittleness.
It also advises keeping collections away from sources of leaks and floods, such as pipes, windows and roof leaks, and away from food and water, which attract insects and rodents.
A worked example: choosing a shelf
You have three places for a box of cards, and leave a thermometer-hygrometer in each for a week. Suppose the readings are: garage, up to 84°F; basement, 62°F but 70% relative humidity, next to a water pipe; bedroom wardrobe on an inside wall, 68–72°F and 40–50% relative humidity. The garage fails the 75°F limit, the basement fails the 65% humidity limit and the pipe rule, and the wardrobe passes all three, so on the Archives' criteria the wardrobe wins. Keep the hygrometer in the box; if humidity climbs towards 65%, move the box somewhere drier.
Boxes and binders
The Archives' rules for papers carry over to boxes:
- Containers should be big enough for items to lie flat or stand upright without bending.
- Boards and folders should be lignin-free and acid-free or buffered.
- If a box is not full, use a spacer so items cannot slump and bend.
- Avoid overstuffing albums and binders, which damages pages and what is attached to them.
Handling
The Archives' advice for photographs fits cards well: handle items by their edges, avoid touching the image area, and wear clean nitrile or cotton gloves where possible, because oils and salts from skin can degrade surfaces over time. It also says to remove paper clips, staples, rubber bands and adhesive notes, which damage surfaces; for cards, that means never bundling them with rubber bands. For dust that could scratch a surface, the Archives suggests brushing lightly with a clean, soft brush or using a hand-operated puff blower, and avoiding canned air because the force of its air stream can cause damage.
Keeping track of what you store
Storage is easier when you know what is in each box, so label every box on the outside. Bulk scanning a card collection covers building an inventory, and card condition grading scales explains why condition matters so much. Before you store an expensive card, how to spot a fake trading card is worth a read.
TCG Card Grading Scanner Value, one of our video and utility apps, scans cards one at a time or in bulk, with every match reviewable before saving, and measures centring from front and back photos. Its grading guidance is informational only; an official grade requires an independent professional grading service.
Good to know
Frequently asked questions
What plastic is safe for card sleeves?
What temperature and humidity are best for storing cards?
Should I store my cards in the attic or basement?
How do I stop cards from bending in storage?
Sources
- How to Preserve Family Archives: Storing Family Papers and Photographs (opens in a new tab)US National Archives and Records Administration — accessed
- Photographs (holdings maintenance) (opens in a new tab)US National Archives and Records Administration — accessed
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