The Armour Archive

Following a link provided by Armourkris ( http://velizariy.kiev.ua/avallon/cuiras ... allery.htm ),
I eventualy got to The Royal Armouries and this abstract to an article published in "Royal Armouries Yearbook Vol 5" -- "Zinc coatings of Indian plate and mail armour"
http://www.royalarmouries.org/what-we-d ... ail-armour
Key phrases:

A group of Indian plate and mail Armours ...earlier than the 1680s ...were found to have been coated in zinc
These Indian armours show the earliest known evidence for galvanising, a process for which the first European patent was from 1836 in France. As with modern galvanising the zinc protects the iron in two ways. Firstly, it acts as a physical barrier to air and moisture. Secondly, because zinc is more electrochemically reactive it provides sacrificial protection to the iron...
Without prior XRF analysis ...this important evidence would have been damaged and eventually lost during cleaning...

Interesting. Of course it raises the question, how much has already been lost without knowing it...

I wonder how they got the zinc on there..

probibly melting the zinc and doing a hot dip. symalar to tinning a piece of cook ware.
Posibly sprinkling powdered zinc on like enamel ware.

Kilkenny wrote:I wonder how they got the zinc on there..

You gotta follow the URL

The mail and plate armour shown (XXVIA.300) and many other examples were found to have been coated in zinc, probably by hot dipping into the molten metal. XRF was able to show this treatment was far more extensive than the limited visible traces.

The Romans, among others, plated with tin. Is there any advantage to using zinc rather than tin for rust protection?

Baron Alcyoneus wrote:The Romans, among others, plated with tin. Is there any advantage to using zinc rather than tin for rust protection?

So the armour is vitamin fortified? *ducks*

Tin can be hard to find in some regions and of more use to alloy with copper for bronze. The cost may also play part but I am unsure.

Baron Alcyoneus wrote:The Romans, among others, plated with tin. Is there any advantage to using zinc rather than tin for rust protection?

Zinc will protect iron better than tin because it forms a galvanic cell with the iron when in the presence of an electrolyte. In the case of armor, the electrolyte might be sweat, blood, horse piss, fingerprints,etc.

In essence, the the zinc gets oxidized instead of the iron. The galvanic effect will extend a short distance beyond the actual zinc coating. This is why the edges of galvanized sheet steel do not readily rust.

By contrast, tin only forms a physical (rather than an electro-chemical) barrier to oxidation. If tin plating gets scratched away, rust will form in the scratch. If zinc plating gets scratched, the exposed iron is still protected. This is why we still use zinc plating; and tin plating has largely gone the way of the high buttoned shoe.

I think it's funny, by the way, that the Indians are still making zinc plated mail. Now, if someone could demonstrate that they were doing in before 1600, maybe fewer people would be asking about how to strip it off!

Mac

Tin just provides a coating; scratch the coating and the bare metal will rust. Zinc actually chemically reacts with the steel so the coating becomes both thicker and more corrosion resistant over time. It's the chemical reaction, not the original zinc coating, that the word "galvanizing" technically refers to.


EDIT: Damn, ninja'd by Mac