Physicists shed light on rarely seen 16th-century metal-working technique

August 4, 2017 by Hayley Dunning, Imperial College London
The gauntlets from a suit of armour - the left one was analysed. Credit: Trustees of the Wallace Collection

Imperial researchers have tested a 'blued' gauntlet from a 16th-century suit of armour with a method usually used to study solar panels.

Metalworkers have used various techniques to prevent steel from rusting, some of which turn the metal black-blue. This 'blueing' effect can be created in several different ways, including by applying heat or (in later years) chemicals.

However, it can be difficult to know which method was used in older metalwork like armour or weapons, because the blueing is oxidised over time, and because many armourers kept their methods protected as trade secrets.

When conservators from The Wallace Collection discovered some blueing preserved beneath the overlapping finger plates of a 16th Century gauntlet, they decided to investigate.

Previously, they had teamed up with Dr Alex Mellor, from the Department of Physics at Imperial College London, to investigate the blueing of a sword blade from 1803, so they knew the method might work. But the gauntlet was a much trickier subject, thanks to its complex shape and the very small area of the surviving blued surface.

How a solar panel is like a gauntlet

The method used is called spectroscopic ellipsometry, and involves studying the reflections of light from the surface of a material. A monochromatic light beam is bounced off the material, and then analysed to see what changes occurred to the beam.

Physicists shed light on rarely seen 16th-century metal-working technique
Dr Alex Mellor (L) and Tom Wilson checking the placement of the gauntlet in the ellipsometer. Credit: Imperial College London

As Dr Mellor explained: "When the linearly polarised monochromatic light beam interacts with a very thin film of material, the direction of the vibration of the light may be altered. This same effect is produced in rainbows or soap bubbles, when the light interacts with very thin films of water.

"Usually, we use spectroscopic ellipsometry in our lab to look at the effect of different films applied to the surface of . If a film can help panels reflect fewer wavelengths of light, then more light, and more energy, can be collected.

"In this case, we were looking for the effect on the light that the thin film of blue produces. By comparing the signature from this experiment to those where the production method is known – such as 19th century guns, or sample strips of metal – we can determine how the gauntlet was blued."

The best and the smartest

After several hours of careful placement and testing, the team were able to get some results from the blued surface of the gauntlet. From their preliminary results, it looks like the bluing is solely the result of heating to around 250°C.

If, when the data have all been carefully processed, this turns out to be the case, then it would fit with the conservators' ideas of how the gauntlet was originally decorated.

Physicists shed light on rarely seen 16th-century metal-working technique
The blueing on this 19th century pistol was created by chemicals and heat, while the blueing on the metal was created using a blow-torch. Credit: Imperial College London

Wallace Collection Consultant Archaeometallurgist Dr Alan Williams explained: "We think the blueing process could be associated with the intricate gilding on the gauntlet.

"Gilding involves chemical etching, followed by application of layers of copper and a gold-mercury amalgam, which when heated fixes the gold to the surface whilst removing the toxic mercury.

"It's during this heating that the bluing could have occurred – coming as a happy side-effect of gilding. For the best quality armour, heat treatment was also a method of hardening the metal; thus heat treatment could produce both the best steel, whilst simultaneously creating a very rich decorative appearance."

Valuable service

The physicists and conservators met in the curious surroundings of Chessington World of Adventures – at an ellipsometry workshop. Dr Williams was hunting around for possible new techniques that could be applied to metallurgical questions, and got talking to Dr Mellor.

Now that their second collaboration seems to have been a success, both teams hope to work together again, in what is a valuable exercise for both. As Dr Mellor said: "It's a good use of our equipment as a public asset. The Wallace Collection is a national resource, and we're pleased to be able to help unravel some of its mysteries."

The whole suit of armour. Credit: Trustees of the Wallace Collection

David Edge, Armourer and Head of Conservation at the Wallace Collection, agreed: "The importance of science in the study of historic artifacts like arms and armour cannot be understated, hence the enormous value of collaborative scientific projects like this."

The armour

Mr Edge then explained the origins of the gauntlet:

"The full set of armour that this gauntlet comes from (cat. no. A62) was made for Lord Buckhurst in 1587 at the Royal Armourers' Workshops in Greenwich - originally set up by Henry VIII at the beginning of the 16th century to provide himself and his Court with the finest quality armour.

"It was almost certainly ordered by Lord Buckhurst with the imminent arrival of the Spanish Armada in mind, the following year. Queen Elizabeth had placed Lord Buckhurst in command of troops along the south coast and he would have wanted a suitably impressive armour to lead them into battle against the Spanish invaders, who everyone was expecting would actually land rather than be defeated at sea.

"It was very definitely made as an armour for war, not 'parade', despite its rich appearance!"

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adave
not rated yet Aug 04, 2017
Koftgari was a similar process in India. No one would want their armour smashed flat on their head or hand so case hardening the parts would give a hard surface with a tough core all in one operation. Guilding just on the front surface with a powder ink allows the carbon to penetrate the iron to form a thin steel skin. Case hardened parts range from a polished blue to a spectrum of mixed color. The colors fade over decades due to rusting of the surface. Blue is the most thick layer lasting the longest. Shields and armour are also work hardened by carved and cold hammered decoration.
Dingbone
Aug 04, 2017
This comment has been removed by a moderator.
rrwillsj
1 / 5 (1) Aug 04, 2017
Damn good thing the Anglo-Dutch "Wooden Walls" prevented Lord Buckhurst and the incompetently led, barely trained, cheaply armed peasant levy following this pompous fool to their grisly deaths against Palma's Spanish veterans.
ThomasQuinn
4.3 / 5 (6) Aug 05, 2017
so that the shiny polished surfaces were preferred.


I am an historian working at a regional history museum and have for several years been involved in the history of arms and armor. "Shiny polished surfaces" were emphatically NOT preferred, in fact, all kinds of ways were devised to avoid them. The 'standard' armor pieces (i.e. of less exalted owners) we have at our museum all have rough surfaces that were clearly never shiny and/or polished. Breast plates/cuirasses were frequently painted (as late as 1914-18 these were in use) or covered in cloth, as was leg armor. Contemporary illustrations from the late medieval era show armor in very dark colors, often close to navy blue or even black, and almost always darker than edged weapons portrayed in the same picture. The only examples of shiny armor I am familiar with are of extremely luxurious suits of armor in aristocratic portraits and a few pieces of luxury tournament armor.
Dingbone
Aug 05, 2017
This comment has been removed by a moderator.
Captain Stumpy
3.7 / 5 (3) Aug 05, 2017
@dingbat zeph
cloth covered armor
Could you provide some link to picture? I never saw something like this actually.
considering your location and it's proximity, why not just go visit Rothenburg Ob Der Tauber in Bavaria
there is a Kriminalmuseum with a great deal of stuff that you can see in person
https://en.wikipe...r_Tauber

there are other armour collections in the area as well, or you can (gasp) google it and check out museum collections without leaving your couch/chair/psyche ward/whatever

in this case, i suggest paying close attention to sources and references, though...

oh, who am i kidding: as long as there is a web page and it fits your bias you will say TQ is wrong, just like you do everything else
LOL
Captain Stumpy
3 / 5 (2) Aug 05, 2017
@ThomasQuinn
I am an historian working at a regional history museum
f*cking cool

are your collections or is your museum on-line
(on line tours)
??

not asking for specifics, just wondering if your museum went digital
ThomasQuinn
5 / 5 (1) Aug 06, 2017
cloth covered armor
Could you provide some link to picture? I never saw something like this actually.


There are three classes of cloth covered armor. The first, and most basic, is simply a separate surcoat worn over armor. This was already in use during the crusades, so before the rise of plate armor. http://manuscript...1-24.jpg

The second, and apparently most common, is plate armor consisting of multiple small plates riveted inside a (padded) cloth covering. This is most frequently found as a brigandine, which covers the torso, but leg armor like this exists too. (inside): https://collectio...289.html (outside): http://ageofcraft...1000.jpg

Finally, there are a few true cloth-covered breast plates, like the Munich Corazzina: https://s-media-c...f534538a
ThomasQuinn
5 / 5 (1) Aug 06, 2017
The hotlink to the Munich Corazzina picture doesn't work and I can't edit the link somehow, sorry. This should work instead: https://www.googl...RP-IYlM:

@Captain Stumpy:

There is a website, but it is not very extensive at this time. We are currently working on plans to expand the digital side of our museum, both in terms of web accessibility and in-house digital features. I don't want to get into too much detail, but we've had a very tight budget over the last five years, mostly as a result of a complex administrative transition and the fact that we have to deal with five separate municipal governments (all of which reduced their contributions to some extent during the past few years), which is difficult at the best of times.
Dingbone
Aug 06, 2017
This comment has been removed by a moderator.
ThomasQuinn
5 / 5 (4) Aug 06, 2017
That is rather a strange remark to make. The term "white armor" refers to the Italian style of specifically *uncovered* armor that came into use in the course of the 15th century. This article is about a late 16th century armor made in Britain in a style partaking of Italian, German and Flemish styles. Your remark that uncovered shiny armor "looked well" is in contradiction to late medieval taste, which preferred colorful, covered armor.

Contemporary illustrations suggest that jousting armor was frequently worn with cloth coverings, despite the advantages of a smooth surface you mention: http://digi.ub.un...359/0068 , http://digi.ub.un...48/0099.

Of course, fechtbücher might be more reliable than artistic images, but they show both covered and uncovered: https://qph.ec.qu...bb2d0a7d , http://68.media.t...1280.png
ThomasQuinn
5 / 5 (4) Aug 06, 2017
BTW: you do a really strange and illogical thing there: first you try to make this entirely about the armor in this article (your first sentence, although you arguably misidentify the armor in question as "white armor"), then you start talking about jousting armor, while the armor above, as the name says, is a FIELD armor, not a tournament/jousting armor: The Greenwich Field Armour of Lord Buckhurst.
Da Schneib
5 / 5 (1) Aug 06, 2017
It's easy to see shiny armor a log way off, and surprise is always a tactical advantage, aside from other considerations of aesthetics you mention, @Thomas. Though I can't say I know enough Medieval history to be certain that tactical considerations entered into armor design. I know more about later times, the Hundred Years' War and so forth.

Do keep telling us more, though, it's interesting. :)
Dingbone
Aug 06, 2017
This comment has been removed by a moderator.
rrwillsj
1 / 5 (1) Aug 06, 2017
It must be me...I'm sure?

Cause I just cannot comprehend why anyone would take these lardbuckets seriously.

Oops, I meant lord buckets...I'm sure!

Bless you alchemists of the world for inventing gunpowder. And of course there should be a monument to Dr, Guillotine. Thanks to all of you for your contributions to Human evolution. By inventing new ways to efficiently cull the viciously-stupid castes.
ThomasQuinn
5 / 5 (1) Aug 07, 2017
Actually the armor in question i.e. the http://i.imgur.com/6cP2ayB.jpg is typical example of so-called white armor used in jousts. For infantry use, only the helmet (without the face-guard), cuirass (breast- and backplates) and gauntlets were worn.


You simply can't make sweeping statements like that, as a lot would depend on the role of the wearer and personal preference. For example, gauntlets would definitely NOT have been worn if the wearer used a firearm or a sword with an extensive hand-guard like a rapier. Likewise, the tassets, the guards for the upper leg suspended from the breast- and back plates, would almost certainly have been worn (as shown in many depictions of 16th century combat), and if the full leg plates weren't used, knee guards (poleyns) would likely have been worn irrespective of whether the wearer performed as infantry or cavalry. Similarly a gorget (neck guard) would seem likely in an infantry role, and maybe shoulder guards.
ThomasQuinn
not rated yet Aug 07, 2017
It's easy to see shiny armor a log way off, and surprise is always a tactical advantage, aside from other considerations of aesthetics you mention, @Thomas. Though I can't say I know enough Medieval history to be certain that tactical considerations entered into armor design. I know more about later times, the Hundred Years' War and so forth.

Do keep telling us more, though, it's interesting. :)


You raise a good point about visibility, but feudal armies were at least *supposed* not to sneak up on enemies, as this would be dishonorable. Still, theory-practice...

Dingbone's suggestion that part of the armour would've been left off for infantry use has a solid basis in fact, but only if the cuirass was made to withstand bullets (i.e. was very thick and heavy), which I don't believe is the case with this armor.

Interesting aside: very little historical armor is what it claims to be. Aside from many, many great forgeries from the 18th/19th century (cont'd below) ...
ThomasQuinn
not rated yet Aug 07, 2017
... many 'suits of armor' were compiled from separate bits and pieces with missing parts added. This was sometimes done in later times, 18th/19th centuries, for collectors, but often, it was already done in the time when the armor was still in use: armor styles changed fairly frequently, so pieces would be added/removed/replaced, and due to its high price armor pieces were kept in use as long as practicable. Most of the museum pieces are from top-of-the-line armor belonging to the highest (and richest) aristocrats, but most wearers of armor would have scavenged, looted and taken as ransom any suitable armor they could obtain in/after battle and had it modified to fit them. So, a suit of armor can be fully authentic and still have pieces made across Europe in different decades.

Interesting aside No. 2: the breast plate we have at our museum was made to be 'bullet resistant', and was actually tested: a mark shows a bullet that bounced off. I gather this test was common practice.
ThomasQuinn
not rated yet Aug 07, 2017
Aside from visibility, another consideration is heat: I understand that the surcoats of the crusades-era were primarily meant to prevent the armor from heating up too much in the hot sun, with other functions (like identifying marks on surcoats) being more of an 'added bonus'.

Although armor is heavy, the weight isn't as bad as it might seem, but due to the necessity for close-fitting padded undergarments (to attach the plates to), you get very hot very quickly. I occasionally wear a replica suit of armor for demonstrations to school classes, and unless there is some wind I sweat like crazy. The weight is not so bad though - our replica armor weighs in at around 25 KG, which is fairly representative for field armor of the early 15th century, but because it is spread out and fairly well-fitted, the weight feels like about half that amount worn in a backpack. I'm far from unusually strong, but I have no problem wearing it for several hours on end. Shoulders get soar though.
ThomasQuinn
not rated yet Aug 07, 2017
Actually the armor in question i.e. the http://i.imgur.com/6cP2ayB.jpg is typical example of so-called white armor used in jousts. For infantry use, only the helmet (without the face-guard), cuirass (breast- and backplates) and gauntlets were worn.


Absolutely not. Please look at what the Wallace Collection has to say about this suit of armor: http://www.wallac...asure/45

"In 1587 he was both ambassador to the Low Countries and also responsible for mustering mounted troops along the South Coast in advance of the Spanish Armada. This richly-decorated but nonetheless fully functional 'field' (war) armour could have been ordered with either task in mind."

"The armour as it appears here is assembled as if for combat on foot; however, by attaching the reinforce breastplate on top of the existing one, and adding the falling buffe to further protect the face, the armour could be converted for use on horseback as a demi-lancer."

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