Why do Pokémon cards bend or curve?

Why do Pokémon cards bend or curve?

Why do cards bend?

Cards bend/warp when they absorb moisture. Try storing them in a cool, dry environment to allow the moisture to evaporate.

Do you have Pokémon cards? If you do, then you know that they can bend or curve over time. Why does this happen and is there a way to prevent or fix it? In this blog post, we’ll take a look at why Pokémon cards bend and offer some tips on how to protect them. So, if you’re curious about what makes your card collection unique, keep reading!


What happens when a card warps?

The cardboard in a trading card is very thin and flexible, which makes it prone to bending or curving. If you kept your cards in your jeans pocket as a kid, with an elastic band snapped around them, they may retain a slight curve to this day. But what we’re going to address is warping.

You’re wondering why the holofoil cards begin to warp, even when they haven’t been under pressure in any way. Well actually, this isn’t true. They are under pressure, and here is why.

Trading cards are either holo or non-holo. Maybe you’ve noticed that the non-holo cards do not warp over time. This is because these cards are entirely made up of cardstock, allowing for expansion and contraction. Holo cards actually have a very thin layer of metal in them, also known as the foil. The foil layer does not allow for expansion in the same way that simple cardstock does. 

When a holofoil card absorbs moisture, the cardstock layers want to expand, while the foil layer does not. This is what creates the curve in the card. This is especially true with promo cards from blister packs. Unfortunately, since the blister is not sealed with plastic, moisture can get in and warp the card over time. 

These three promo cards came in blister packs

Humidity and climate play a big part here. If you live in a humid place or perhaps your house is kept humid, this is going to be an issue for you.   

Does it hurt the value of the card?

Grading companies are known to be strict. Even the smallest of scratches or creases can sometimes drop the grade of a card by a whole point. This can be detrimental if you are trying to increase the value of your card. 

Luckily, grading companies do not take card warping into account when they assign grades. Why? Because it’s not actually considered permanent damage to the card, such as whitening. Once the card is finished grading and encased in a slab, it will be laid flat and upon receiving your card, you won’t be able to tell that it was ever warped.

Can it be fixed?

As mentioned above, the warp occurs when the card absorbs moisture. Once the moisture is absorbed, it remains in the cardstock. The good news is that upon the moisture evaporating, the curve will go away.

That’s right, you can fix it.

Keep your cards in a dry cool place, and some of the moisture should release. To get your card back to its fully flat state, try sleeving it and placing it inside a large book, and apply some weight for 48 hours. This can sometimes flatten out the remainder of the curve.

Another option is to evaporate the moisture yourself. This is a risky procedure and becomes direr with the rarity of the card. 

Upon applying heat to the card, the moisture will evaporate, and the card will flatten out. This can be done using a blowdryer. This is risky. Please do not try this with your most valuable card. And as always, test this method first with a card of lesser value. After applying heat from the blow dryer, sleeve the card and place it in a book to retain the new shape of the card.

How to prevent warping

If you can determine how to prevent moisture from reaching the card, you can prevent warping. A simple way to do this is to immediately sleeve your cards and put them into a binder. 

If you want to take further precautions, you can purchase or even reuse silica packs. These are the little bags of silica that you get when you buy a new pair of shoes. They are designed to absorb the moisture from the air, to keep the product dry. And that’s exactly what we want to do, keep our cards dry. Throw some of these packets into your binder, drawer, or wherever you store your cards.

If you want to take it even further you can use closet de-humidity packs, or buy a dehumidifier.


Cards warp because the foil layer of the card does now allow for expansion when the cards absorb moisture. But luckily, this is reversible as long as the moisture can be evaporated. The best practice is to immediately sleeve your holofoil cards and put them away in a safe place. If this isn’t doable, or if you live in a very humid climate, try different methods to dehumidify or absorb moisture from the air, to avoid it getting into your cards.