There is a type of Roman armour that seems to use all latten links in its construction and that is the lorica plumata. This armour is made from very small links being woven with small scales. The protection this armour offered would have been minimal. I and others feel it was for ceremonial purposes and nothing more because of this.
I think it's very interesting that you brought up lorica plumata, I have been researching this type of armor quite a bit lately, and was recently discussing it via email with Mathew Amt, who is the technical advisor of Legio XX, one of the largest Roman Re-enactment / Living History groups in the US.
There is a guy who is trying to reconstruct some plumata, you can see his progress here:
http://members.sockets.net/~firemsn/plumatapics/plumatapics.html I wonder if he'll let us cut it when he's done <img src="http://www.thearma.org/forum/images/icons/wink.gif" alt="" />
I wonder about the contention that it is for show. I know that many other historians have suggested similar theories to your own regarding plumata and also the lorica squamata, the 'traditional' type of scale armor which was worn by Roman cavalry and auxiliaries. The claim is specifically that all forms of Roman scale armor were worn because it looked better in spite of being inferior armor.
Unlike Lorica Squamata, Plumata, (named after the appearance of bird feathers) was worn by standard bearers and high ranking artistocratic officers. Standard bearers were very important and prominent, having advanced from the ranks of the highest ranking centurians. They carried the most precious posession of the legion and often fought in harms way in front of the infantry squares (maniples / centuries), and long after the light - armed velites had retired to the rear.
My question is, why would Roman officers wear inferior armor, especially when they were going to be in harms way? Evidence from columns etc. seems to indicate that this armor was worn in battle. If all they wanted to do was look good why not wear cloth of gold or purple togas? Why go to all the trouble of riviting tens of thousands of tiny links, and wiring scales onto them? If it was just for apperance wouldn't something much simpler be in order?
I'm not an expert on armor or metalurgy, but it seems logical to me that if it were made of a strong metal, a lorica plumata shirt would be extraordinarily good protection.
When I suggested that ordinary scale armor was inferior, Mathew Amt pointed out to me that some caution should be used in rushing to judgement on this issue, remembering how people thought mail was inferior based on tests in the 70s...
I didn't realise that most plumata was believed to be brass. Is there any known find of what seems to be plumata that is made of iron or steel? Or is it all brass? (latten or orachulum)
I have heard some references to the scales of plumata being coated in 'white metal' believed to be silver or tin. Wierd!? Makes me think of a comment John C. made about a lot of medieval mail armor being lacquered. Would plating help with corrosion?
I have seen some metalurgical charts which seem to indicated that certain alloys of brass were actually stronger in some aspects than mild steel. Was I reading those charts wrong? If not, is it possible they had such alloys in the Classical period? I know they experimented with various combinations of copper with arsenic, zinc, tin, and other metals...
JR