dating when what type of rivet appeared when, is always going to be somewhat difficult, especially as maille had the habit of being re used over the centuries. I have a nice example, albeit small, section of maille thought to be circa C14th wedge/flat ring with a few brass links attached plus a repair that is characteristic of late C15th (round ring and round rivet) The other thing to note is that there were also regional differences with some areas remaining wedge when things shifted back to the pin rivet. Wedge does appear to have been around before the C14th. Possibly even as early as the C11th, but as I said the issue is with getting accurate dating.
This has reminded me that I need to get get hold of a copy of a report of a coif found in 2004 in Tofta church in Gotland. The hood is well preserved with leather straps, which in itself has allowed for some carbon dating to be done, suggesting the 1200s. The links look very much like being wedge riveted and certainly very flat, but I need to see the report as I gather the images are much clearer on it than what is shown on the website.
I think I have put a link on the forum before but in case not http://www.actakonservering.se/acta/Kon ... .html#grid
and yes Colin is right, doing maille demo's at an event does get a very positive response from the public.
As well as riveting I tend to talk about the process as a whole, wire drawing, making the rings etc, which in itself people do seem to find interesting, especially when you point out that despite the long history of maille, we are not 100% sure on what tools were actually used or how the industry as a whole worked. I'm also working on a small forge to demonstrate forge welding rings..