Quick answer
CardSpicy sells the protection layers this article puts in context, and cards almost always fail slowly, for reasons that have nothing to do with how they are handled.
Cards almost never fail suddenly. They change slowly, and they change for four reasons that have nothing to do with how they are handled. CardSpicy sells the protection layers this article puts in context, and the layers only work if the room they sit in is doing its part.
The one line: the enemy is not dust, it is the environment. Moisture, light, temperature swings and the materials touching the card do the slow damage, and they work whether or not the card is ever taken out of its sleeve.
What actually degrades a stored card
| Factor | What it does | How reversible |
|---|---|---|
| Moisture | Paper takes on and releases water with the air, which swells and shrinks the card and, with it, the printed layer on the surface. | The distortion from repeated cycling is not reversible. |
| Light, especially ultraviolet | Breaks down the dyes and the coating that carries the image, so colours shift and paper yellows. | Not reversible. Storage changes the future, not the past. |
| Temperature cycling | Repeated warm-and-cool cycles move moisture in and out of the card, which is why a fluctuating room is worse than a steady one. | Not reversible once the card has cycled many times. |
| Contact materials | Plasticisers and acids in the wrong plastic migrate into the card surface over years. | Not reversible. |
Four factors, and only one of them is a mistake a collector makes on purpose. The rest are properties of the room.
Humidity
Paper is hygroscopic, meaning it takes on and releases moisture with the air around it. A card in a humid room is not wet — it has swollen slightly, and the printed surface has moved with it. Nothing looks wrong. Then the air dries, the card contracts, and a surface that has swollen and shrunk many times has begun to change in ways that do not come back.
The figure most often quoted for paper-based collections sits in the middle of the range and comes with the same caveat every time: a stable value is better than an ideal one. A collection held at a steady mid-range humidity in a normal room is in less danger than one held at a perfect number that swings by twenty points every day, because it is the cycling that does the damage rather than the average.
Practically, that means humidity is managed by choosing the room rather than by buying something. Avoid basements and attics, which swing hardest. Avoid a shelf against an outside wall that goes cold overnight. Keep storage away from bathrooms, kitchens and any room where the air changes with the weather.
Light
Light damage is the slowest of the four and the one most likely to be dismissed, because the first year shows nothing. It works in two layers: ultraviolet does the majority of the damage per unit of exposure, and ordinary visible light still contributes over long enough periods.
Two consequences matter for storage. Window glass is not a UV filter, so a card in a closed box on a shelf that gets sun is only partly protected by the box unless the box is opaque and never opened in that position. And darkness is the only real remedy, because fading does not reverse when the light goes away.
The display side of this trade is covered in display frames and magnetic holders, where the point is that a frame is about how a card looks rather than how it survives.
Temperature cycling
Temperature matters less for its own sake than for what it does to moisture. Warm air holds more water than cold air, so a card that sits in a room which warms and cools through the day is sitting in air whose moisture content is changing, and the card follows. This is why a garage, an attic or a shelf above a radiator is a worse home for a collection than the numbers on a thermometer suggest.
The remedy is the same as for humidity: keep the storage in a room where the temperature is boring, and do not store cards where something else in the room is periodically hot or cold.
What desiccants do, and do not do
Silica gel and similar desiccants get packed with collections on the theory that they keep the cards dry, and the reality is narrower.
- They absorb moisture from the air in a closed container. That is a real effect, and in a sealed box it is measurable.
- They saturate. A desiccant that has taken up all it can hold stops working and can give moisture back, so it needs to be dried or replaced on a schedule rather than left in place indefinitely.
- They do not stabilise a room. A desiccant in an open box in a humid room is absorbing the room, not protecting the card.
- They can over-dry. Driving a paper collection far below the ambient level is not an improvement; paper wants a middle, not a minimum.
Treat a desiccant as a tool for a sealed container, not as a substitute for choosing a sensible room.
A slab is not sealed against humidity
Graded slabs are sealed against opening, which is a different thing from being sealed against air. The card inside a slab is still in contact with air that moves with the environment, so a slab stored in a damp room is a card stored in a damp room. The case adds rigidity and a tamper-evident closure, and this article’s list of four factors still applies inside it.
That is also why slab storage is still a storage question: bag the slab for the case surface, then put it in a closed box in the right room. Whether a graded slab needs a sleeve covers the first step, storage boxes the second.
Frequently asked questions
What humidity should cards be stored at?
Guidance for paper collections generally points to the middle of the range, and every version of it comes with the same caveat: stability matters more than the exact figure. A collection in a normal room at a steady level is safer than one at a perfect number that swings daily, because the cycling is what damages the card.
Do silica gel packets protect my cards?
Only inside a sealed container, and only until they saturate. A desiccant absorbs moisture from a closed space and then stops working, and can release moisture again. It is not a substitute for keeping cards in a dry, stable room.
Do graded slabs protect a card from humidity?
No. A slab is sealed against being opened, not against air. The card inside is still exposed to the moisture in its environment, so a slab in a damp room is a card in a damp room. Rigidity and tamper evidence are what a slab adds.
Can I store cards in a garage or attic?
It is the worst place for them. Garages and attics have the largest daily and seasonal temperature swings of anywhere in a house, and temperature swings move moisture in and out of paper. A cupboard inside the living space is a better home than a protected corner of an attic.
Does light really damage cards in a box?
A closed opaque box blocks light while it is closed, which is most of the protection. The risk is in how the box is kept: left open, stored on a sunlit shelf, or replaced by a clear container. Fading does not reverse, so exposure avoided is the only exposure recovered.
Sources
Sources and further reading
- General conservation guidance for paper-based collections on the hygroscopic behaviour of paper, target humidity bands for storage, and the priority of stability over any single ideal figure.
- General conservation guidance on ultraviolet and visible light as causes of fading and yellowing in paper and printed surfaces, and on the irreversibility of that change.
- CardSpicy product specifications for the rigid 3" × 4" card holder range and the 100x penny sleeve range, used when describing the layers that sit between a card and its room. Retrieved 2026-10-06.
- Published dimensional and construction data for third-party graded slabs, used here to distinguish being sealed against opening from being sealed against air.
This page is general guidance on storage conditions, not conservation advice for a specific item or a valuation of any card. Where published sources differ on exact figures, this page states the principle rather than a number.
Related reading
- Storage boxes: what actually protects a collection
- Display frames and magnetic holders for graded cards
- Does a graded slab need a sleeve?
- Sleeves, holders, binders and storage
Where to go next
- The CardSpicy card index — every card we track, with its PSA 10 population and market history (195 cards).
- The illustrator index — every artist behind those cards, card by card (110 artists).