How to store sealed booster boxes and ETBs

Keep sealed boxes in their shrink wrap, inside a closed carton or tote, on a shelf off the floor in a lived-in room that stays cool, dry and dark. Keep stacks short, and never load weight onto a single box. The main threats to a stored box are damp, swings in humidity, crushing, pests, light and heat.

For loose cards, see our guide to storing trading cards, and for slabs, storing graded cards.

Why does storage matter for a sealed box?

Because the box is the product. Sealed product is bought for what is inside, and its condition is judged from the outside. TCGplayer sets a strict line for what sellers may list as factory sealed. Three things have to hold:

• The seals. Every seal is unbroken and nothing shows tampering.
• The wrap. The product has never been re-shrink-wrapped or resealed.
• The packaging. It is the original, unopened packaging, with no rips, no missing pieces and no damage or wear anywhere on it.

Under that standard, a crushed corner or a torn wrap can stop a box being sold as factory sealed on TCGplayer, even if the packs inside are untouched. It also means a box you rewrap yourself no longer qualifies. Our guide to spotting a resealed Pokémon pack explains why buyers look so closely at wrap and seams.

What damages sealed product, and what stops it?

How fast does mold start?

CCI’s mold timings explain why a damp spell matters more than a single humid day. For its most mold-prone surfaces, such as starched, sized or dirty paper, CCI gives about 100 days at 70% relative humidity, about 10 days at 80% and about 2 days at 90%, for temperatures near 25°C. For clean plant-based material such as clean paper, it says mold typically needs 80% to 85% before it is likely at all. These figures are for paper, so for a booster box treat the stricter 70% line as the one to stay well under.

CCI adds that a level held just inside the danger zone is still a problem, and that dropping back to a safe level every few days resets the clock. At 60%, it says, mold is just possible on some surfaces, though a steady 60% is rare, and any spell below 55% stops growth.

For long-term paper storage, the Library of Congress suggests about 35% relative humidity at room temperature or below. Our card storage guide sets that target beside CCI’s 75% boundary for damp.

Does sealing a box in plastic keep damp out?

Mostly, as long as the box is dry when you seal it. CCI says moisture-proof packaging helps almost every collection, but names three ways it goes wrong:

1. Damp sealed in. A damp object packed in a bag or tote stays damp far longer than one left open.
2. Uneven temperature. Condensation forms at the end of a package that stays colder than the rest, as when an uninsulated package sits against a cold wall.
3. Swinging rooms. Where damp and dry spells alternate, a package levels out the daily swings and reduces the seasonal ones, but whether the inside stays in the safe zone depends on several factors.

So pack boxes only after a dry stretch, keep totes off concrete floors and away from cold outside walls, and if you are unsure, CCI’s advice is to measure the humidity inside the package.

Where should sealed product go?

In a lived-in room. The Library of Congress advises against attics and basements for paper, as places prone to leaks and extremes. CCI says basements, and ground floors with no basement, tend toward damp, and that shelves against outside walls see high humidity in cold weather. State Farm’s collectibles guide adds the garage and flood-prone areas, and suggests sealable plastic bins kept well above ground level.

Shelving matters too. The National Park Service’s guidance for museum storage puts the bottom shelf 6 inches off the floor, to make cleaning easier and protect against water. It also says museum shelving should have no wooden or particle board parts, because those materials are acidic and may give off gases. If your shelving is wood or particle board, a closed carton or tote between the box and the shelf adds a layer.

How should you stack booster boxes, Elite Trainer Boxes and cases?

Lightly. CCI’s guidance on physical forces says that when packages are stacked, the ones lower down carry the weight of those above, and that the shock and vibration of a moving vehicle magnify that load. State Farm’s display advice, written for heavy items, says to stand them upright rather than stack them, to prevent warping.

Three habits follow from that:

• Keep stacks short. A tall stack puts its whole weight on the bottom box.
• Put heavier items lower. A full case or a large collection box should not sit on an Elite Trainer Box.
• Unstack before you move. Take stacks apart for a car trip, since transit adds force.

For what an Elite Trainer Box holds, see our guide to Pokémon sealed products compared. A booster box is a box of packs, and a case is the shipping carton that holds several boxes. If you keep a case sealed, its carton adds a layer against light and dust, but it is still a stack inside, so treat it as a heavy item.

Is a clear display case safe?

Only out of the sun. CCI’s light guidance says UV usually causes less than half of fading, often a tenth, so a case that filters UV removes only part of the problem. For highly light-sensitive colors, CCI estimates a just-noticeable fade in about 1 day to 2 weeks of strong daylight (30,000 lux, 8 hours a day). Its temperature guidance adds that surfaces enclosed by glass, as in display cases, can get even hotter than surfaces in open sun.

If you display a box, pick a spot with no direct sun, away from heaters and vents, and measure the box before buying a case so it slides in without catching or tearing the wrap.

How hot is too hot?

CCI’s rule of thumb is that each 5°C drop doubles an object’s lifetime, and it suggests keeping a room below 25°C in summer and above 5°C in winter. Shrink wrap and plastic cases are plastics, and CCI lists the heat distortion temperature of many common plastics at 65 to 90°C. It also warns that a vehicle without climate control can get far hotter than the outside air in summer, and that some common white glues soften above 30°C. Do not leave boxes in a car after a store run or a card show.

What does a good setup look like?

1. Leave the shrink wrap on and handle the box by its sides.
2. Pack dry boxes into a closed carton or a sealable tote.
3. Shelve them in a lived-in room, 6 inches or more off the floor, away from outside walls, the attic, the basement and the garage.
4. Keep stacks short, with heavier items at the bottom.
5. Keep the boxes dark, or display them out of direct sun.
6. Put a hygrometer nearby and check it, along with signs of pests, every few weeks.
7. Keep a list of what you store, with photos and receipts.

That list matters for insurance as well as for selling. One collectibles insurer, Collectibles Insurance Services, lists damp or dry air, changes or extremes of temperature, infestation by insects or rodents, and gradual deterioration such as fading among its exclusions, so under a policy like that, those losses stay with you, and storage is how you limit them. Our guide to insuring a card collection compares policy types. To buy sealed product at a store’s own price, see where to buy Pokémon cards at MSRP, and for what each format holds, Pokémon sealed products compared.

Frequently asked questions

What kind of shelving suits stored booster boxes?

Powder-coated steel, adjustable rather than fixed. A liner between shelf and box, cut to the shelf's exact size, adds cushioning, in materials such as corrugated polypropylene, polyethylene foam or acrylic sheet.

Can mice reach boxes stored far from the kitchen?

Yes. A mouse usually keeps to a territory of about 20 meters but can range up to a couple of kilometers, and most rodent problems in buildings start with human food, so keep food and garbage out of any room near the boxes.

Does a collectibles insurer ask where sealed product is kept?

Yes. Collectibles Insurance Services asks whether any items sit in a basement or other area below ground, or in a public storage facility, and has you confirm you can prove ownership with photos and an inventory, transaction records or an appraisal.

Does smoke harm displayed boxes?

It can stain them. Smoke residue marks displayed collectibles, so keep a display in a smoke-free room, out of the reach of pets and small children.