Norman chain mail and 1066 armour/dress in general

[Gwydion]

Thanks Mark.

[Gwydion]

Okay, tracked down a reference to a medieval indenture of 1344 which appears to suggest the process may have been used:
C W King, The Archaeological Journal 1866 pp79-95
'In the time of Ed III mail armour was  cleaned by rolling it in a barrel with sand probably or emery. See the Dover Castle Inventories  Arch Journal, vol xi pp.382, 386'

And sure enough:
The Archaeolgical Journal vol 11, 1854 p.381 –  Albert Way
'Original Documents – Accounts of the Constables of the Castle of Dovor. Records of the Queen's Remembrancers preserved in the Branch Public Record Office, Carlton Ride.
Indenture dated Dec 20, 17 Edw. III, 1344.'
p.386
'There was also found in the Aula a barrel "pro armaturis rollandis'' Armour of mail was cleaned from rust by a simple process of friction namely by rolling it in a barrel, probably with sand, and this continued in use as late as 1603, as appears by the inventory of Hengrave Hall where was found in the armoury – "one barrel to make clean the shirts of mail and gorgetts". Eastern nations by whom mail is still worn, brighten it, as Sir S Meyrick observes, by shaking it in a sack with bran and sand'. Vinesauf describes the warriors of Coeur de Lion as whirling their hauberks for this purpose- "Rotantur loricae ne rubigine squallescant".'
So not Roman yet, but probably genuine medieval practice. (the Dover indenture doesn't actually mention mail or sand, and it is Mr Way's undocumented explanation that this method was used  that ties it together with the 1603 inventory, but it is looking firmer than a wet finger guess).

[Lord Kermit of Birkenhead]

Good stuff there