Does heat do anything bad to cards?
 

I live in Australia so hot days (particually in the summer) are not rare.
I have noticed that if I leave cards out of ther box for a few hours on a hot day they go all kind of :thinking: umm.. clicky. You can click them into 2 postitions one when the cards are bent the normal way an the other they are bending outwards instead of inwards. This is a little anyyoing because when I search through the deck face up it clicks and if I have the cards face down and I push down on them they click.

Does anyone know why this happens and is this bad for the playing cards?

Also I have been camping for the past few days and I left my cards in the tent one day and when I came back they where very hot.
So another question:

Does heat do anything bad to cards?

Ah, the heat does that to cards very often. I suggest you put it in a drawer or someplace cooler away from the sun to avoid that from happening.

I don't believe this is especially bad for the cards, but the constant contraction and expansion of the cards may end up worsening the condition of the cards eventually.

I think that heat does speed up the process of decay on the cards, and I mean decay in the sense of life span of the card's usage. As for the heat, although I'm not sure, it seems to me that when cards are older, heat usually makes it worse from some reason. Probably all the science stuff about how heat speeds up the molecules' movements and etc. :(

But in general, I think you should avoid heat as much as possible and try to keep your cards in a cooler place such as a closet or drawer or even the basement.

yes, heat IS bad for your cards, especially when you use it often, the cards won't handle very well for you( flourishes mostly, but some techniques could look very bad if you've got a hot deck). I'm not 100% sure about the science behind it, but apparently, if you leave a card with a bit of moister in it and you have a heat source, the card will bend, and/or gets soft, and softer cards can sometimes mean a really "flashy" performace( as in a lot of flashes)

Heat alone mostly won't do any harm to your cards, and it shouldn't be a problem at all if it's both hot and dry, but if you hold to card while it is hot, there might be a problem.

Moisture combined with heat, and also being near an open window will warp the cards and cause that "Click" you mentioned - I've had the same problem. Store your cards in cool, dry place and you should be alright

^ +1

It's the reason why Australia might as well be the worst place to live if you want to store playing cards. :(
I store my cards in my studio over here, in which it's pretty hot at times but also very dry so it's all fine. ^_^