Originally Posted by Chris Wallace
Hmm-I'll buy that to a certain extent. I tend to think that Wolverine's Astonishing costume was made of leather, due in part to the sheen & the pronounced zipper. But many artists did have it looking like spandex. IDK what Cap's suit is made of, but it ain't spandex. They say all the time that Batman & Co. are wearing nomex layered over kevlar.
I tend to assume that most costumes aren't made of spandex, because spandex is A) Often impractical for the stuff the characters are doing, and B) In the case of characters who make their own costumes, spandex isn't very good for sewing with, unless you have it be so thick that it removes the benefits of spandex. I tend to assume that Spider-Man's costume, for example, is made from inexpensive cotton of decent quality.