Linothorax vs Quilted linen vs spolas

[MeinPanzer]

furthermore, it was in widespread enough use that a word was made up to describe it.

Doesn't "spolas" refer to a leather apron of the kind that a blacksmith might wear originally?

Sorry, that statement was a bit unclear. I meant that this word came to refer to one kind of armour (though it seems to have also had a more generic meaning in some cases), as opposed to the earlier linen cuirasses, which are just called some variant of thorax lineos (and not linothorax).

As i said,we see these pteryges in sculptures and not vases after the 4rth century bc. In sculpture we can have a better idea of how sowft,thick and thin the matterial is. Also there are mosaics like the famous Alexander mosaic that show that the matterial of the pteryges at least was soft
Look here: http://www.flickr.com/photos/mirjam75/1417436348/

Firstly, the thickness of the pteruges on bronze sculptures from the ancient period cannot be used to determine the thickness of actual pteruges for the quite obvious reason that bronze and whatever organic material they were made of are very different materials. Secondly, we have absolutely no idea how soft the pteruges shown on the Alexander mosaic are because it is a two-dimensional representation. That being said, even if you held the notion that the softness of something like pteruges could be determined from such representational art, the pteruges of Alexander's cuirass certainly seem to be quite stiff, and so I have no idea how you could argue that they are soft.

Pollux mentions two names, Xenophon and Aristophanes. And he also gives two definitions of spolas,the first of which is "the leather chiton".

The reference to Aristophanes comes from the preceding entry on the sisura ("He de sisura periblema an eie ek diphtheras: en pente sisurais egkekordulemenos Aristophanes legei") and has nothing to do with the spolas. The second individual that he mentions is Sophocles, whom he quotes as "calling it Libyan:" "A Libyan spolas, a leopardskin." This second quotation does not provide another definition, but is merely another demonstrative quotation, and one that is hardly of help considering that it is poetic and likely mythological in nature. He never calls it a "leather chiton."

Actually we do have. Didn't Iphicrates use linen cuirasses? Of course we are not told what the linen cuirasses of iphicrates took the place of,but it could even be no cuirass at all!

The statement that Iphicrates' troops used linen cuirasses comes from Cornelius Nepos. He was a later source, which does not necessarily invalidate his statement, but his claim that Iphicrates replaced "linked armour" ('loricarum ... sertis' - Life of Iphicrates, 1) with linen clearly does. His is the more confused of the two sources referring to Iphicrates' reforms, and his account is not to be trusted.