Leather Cuirass

[Tarbicus]

The famous "Lyson and Kallikles" tomb showing buff corselets/pteruges and painted helmets

I'm sure painted shading and over 2000 years of discolouration might make them seem buff, but I think they're far more likely to have been white.
http://www.ypai.gr/atlas/images/photos_big/3_2.jpg
Even if they could be seen as off-white, that ties in with linen perfectly.
To put the photo I just posted into some colour reference, here's another photo of another part of the tomb shot under different conditions.
http://www.macedonian-heritage.gr/Helle ... l/d14g.jpg

Many Southern and Central Italian tomb paintings show soldiers wearing white and off-white cuirasses.

Exactly like linen.

If leather, what paint would be used to create the patterns we often see on the representations of cuirasses under discussion, bearing in mind they were quite flexible? Or, how would the patterns and decoration be made?