ISTR we discussed this back in 2017, I tried to find it on this site, maybe somewhere else on web or.... If you could point me to it, great.
Anyway, in _Armies and Enemies of Imperial Rome_, in the discussion of figure 9, "Legionarius of the mid 3rd to 5th centuries AD", Mr Barker says he's wearing a "moulded muscle cuirasse of rawhide". IIRC, several people said that evidence available in the thirty years since AEIR indicated otherwise.
I'm thinking, first, that in a wet climate or season, rawhide would need to be protected from water or it would lose strength rapidly - oil, wax, paint?
Or is Legionarius 9 actually wearing a cuirass of iron or bronze, or chainmail ? Have some figures sculpted as copy of Figure 9, how would you paint them ? Thanks for your help with this.
Current thinking is toward mail armor for those that actually had it. No leather cuirass has survived to be found as of yet... we just have sculpture and paintings for any proof... those of course could be artistic license. Phil's point is that this license was ubiquitous if it existed. In short, no one knows. I used mail for my 15mm troops and leather for my 25mm. Do what you think looks the best.
The leather cuirass is generally shown as a lighter brown.
A bit late, but as per discussion recently on TMP, I fall in the H. R. Robinson camp - Late Roman armor is mail or scale. Leather has a number of drawbacks and I fail to see the Romans as making that step backwards.
When I have figures modeled with leather armor (mine are 15mm) I paint the armor as bronze or iron.