**So, I own a Japanese Base Set booster pack, and it’s been weighing very light, although my $15 amazon scale is screwed up.
However, today I realized the front card is curving. As far as I’m aware, only holo cards curve with humidity; many of my cards that sit out in my room start curving, but only holos. I used to own some other gen 1 japanese packs, and you could feel the cards in the front (where the rare is) curving.
The fact that the rare card in my base set pack is curving makes me think it’s a holo. Is there any legitimacy to this? If so, kind of exciting since I believed it to be light before!
(By curving, I mean, picture you hold your card by the sides and squeeze a bit, giving it a C shape)**
Really depends how they were stored. Holos do curl more prominently than non-holos, but if it’s a loose pack that you dont know much about it’s orgigin, I’d go by weight. If it’s very light then likely non-holo. If it’s on the edge, then maybe.
I’ve owned it for 5 months or so now, and it wasnt curving when I first got it. It just sits on a little plastic stand on my desk in my room, but like I said, most holofoil cards that sit out on my desk curve, along with the ones in other packs I’ve owned.
My scale was a bit light when I first got it, and it weighed 16.47. Pretty light, but coins were weighing light so I’m not sure its actual weight
Not 100% sure about Pokemon cards, but yes, I would assume the holofoil makes cards curve. I know for Magic, foil cards curve when the cardstock quality is poor. I’ve also heard and read that wide temperature variations and moisture can make foil cards curve. I’m guessing the paper cardstock subtly changes shape in response to environmental conditions, while the foil doesn’t react in the same way, causing the card to curve (mostly inward toward the foil since the paper cardstock is likely to expand). So my guess would be, yes, foil cards are likely to noticeably curve, while non-foil cards don’t as much because the cardstock reacts to the environment proportionally on all sides. Please don’t take this as gospel though, just my thoughts.
I have always thought this was the answer as well. One side expands contracts more because it’s made of paper, and the other much less because it’s plastic/non-paper, putting uneven pressure on the card.
All cards have the ability to curl, but as many stated here already foils naturally have more of that ability due to exactly what they are: foils.
Think of it like this: all cards have layers, and foils have the difference of including a foil layer. When moisture enters into the cardboard aspect of said card, the foil remains the same while the cardboard “swells”. As this occurs more and more, that curl effect can be seen as it remains stiff and the layers pull against each other because the foil doesnt have that same ability to absorb moisture as the cardboard aspect does.
Now in terms of regular cards curling, ive seen this happen but cant really give a reason as to why of course. Maybe its because even though its cardboard, the cardboard layers may be different in the cardstock when its printed. Im pulling this out of thin air here, but could be safe assumption. Thing though is its never to the same degree as foils, and usually a foil curl is very tellable compared to that of a non holo. Ive had theme decks where you can see the whole deck (japanese ex decks) and this can been seen when tilting the deck to see the comparison.
Super helpful, thank you! I’ve never personally had regular cards in my room curve, only holos, which is why I believe the rare card is holographic. However, without a scale, or even if it weighed light, I’d have a hard time proving it over video for sale purposes. I can’t exactly prove to anyone that because of my humid 2nd floor room, holos curve all the time, haha.
Still pretty cool to know, and maybe I’ll keep it or open it one day just to find out.
To re-affirm what others have said, and offer a piggy-back on what @dizzle24 suggested, perhaps, even on a non-holo card, the ink was too hot such that, when the top layer cooled, it curved inward (concave)? When it’s simply a matter of moisture, non-foil layers generally get “wrinkly” (I don’t know how to describe it really), kinda like your fingertips when you sit in a tub or pool too long. Curving is a matter of material physics. If the foil layer was too hot when applied to the cardstock, it can be curved almost immediately or even IN the pack, as the foil shrinks due to, you know, cooling. If the card is exposed to moisture, the cardstock can absorb moisture from the air and expand. If you lay a card in the sun or if it’s in very warm conditions, the foil can expand, but should revert later… I’ve never seen a card curl IN a well-sealed pack *over time*. However, my oldest sealed is about 10 years.
Theoretically though, I’d expect a good seal to prevent moisture exchange over time. Look with a magnifying lense and see if you can find any breaks in the seal of the pack, especially around the crimping, I’d suspect.
I recently opened a mint heavy shadowless blister and the holo was curved (enough so that you could see it if you looked down at the top of the cards after doing the card trick so that the holo would be at the back). Case fresh blister, no moisture damage. I guess holos naturally curl over time (think eseries cards, they do that a lot) and it has nothing probably to do with moisture absorption.
Anecdotal evidence is good. However, I have to wonder if it was always curved just after printing, due to some of the manufacturing processes I mentioned earlier. Not saying you’re wrong, just playing devil’s advocate. I imagine it would be nearly impossible for moisture to get at the card after sealing the blister. I’ve opened curved cards in packs, but can’t say I’ve witnessed them curve over-time before opening. Lots of variables in manufacturing. I wonder, what the SnP are of trading card manufacturing facilities… Masks? probly not. Hair covers? maybe. Air filtration…?
Potentially, many factors at play. Imo things age overtime, likely reacting more to how they are stored. Heat maybe? Or maybe just the mateiral. It seems to be a very common thing with early WOTC (and E readers as there is a lot more foil). Rusty has a few videos where he coins the “curve test” where you check the back card from the top after doing the card trick. Very common.
Where I live in the UK the humidity swings from 30% to 80% throughout the year and above 70% any card will start curving. Holofoil cards will start curving at lower humidity. I can’t say much for cards inside booster packs, mind you.
If this data point helps in any way: My Dream League and Shiny Star V cards (including non-foil) all curl in the winter when we need more heat in the home (cold winters in Canada). The foil cards definitely curl “earlier” and to a higher degree.
I am pretty confident these are authentic as I purchased them before the hype (and also did a rip test on commons). In general, the possibility is there if the cards are stored in an environment that differs significant from their production. I suspect this plays a role given they’re imported cards.