Early Use of Plastic Armour

[Justin Swanton]

Here's an interesting find. A team of archaeologists digging in a locale in northern Iraq recently evacuated by ISIS found elements of lamellar armour made of a primitive form of plastic. It seems the technology for refining crude oil - then visible in pools at certain places above ground - existed around 2000BC, enabling weapons manufacturers to experiment with the fabrication of plastic scales suitable for armour. The limited nature of the finds - only one incomplete suit of scale armour at one site discovered so far - would seem to suggest that plastic armour was deemed not to be a success and its manufacture was quickly abandoned.

The more things change...

[Erpingham]

It's that kinda day, I suppose.

[PMBardunias]

Just to add to your day.  I did some experimentation with Greek armor that makes use of non-Newtonian physics, so who knows.  From "Hoplites at War":

Aelian uses an enigmatic term argilos, meaning 'white clay', to describe an armor appropriate for light troops.[1]  Some have translated this as a bright white tunic, while others have taken him to have meant 'flashy'; however, it could well be that he literally white-colored clay.  A type of fine white clay, known to as kaolin, was widely used by the ancient Greeks.  It was a white pottery glaze, and a slip of kaolin formed the drawing surface on white oil jars (lekythoi), which became popular in early the 5th century.  Theophrastus of Eresos, on Lesbos, in his late 4th century treatise On Stones described possible kaolins as Melian and Samian earths.  They were commonly used in fulling and bleaching textiles.

We are benefited in our study of ancient armor that textile body armor has come back into fashion.  A recent study showed that the ability of Kevlar armor to defeat spike and knife threats can be significantly increased if kaolin is intercalated into the weave.  The clay stiffens through a process called "shear-thickening", wherein the clay-coated fibers are pliable if slowly pushed against, but resist sliding past each other at speed and when impacted at high velocity.  This sees the clay particles form an atomic lattice that for the briefest moment is hard as ceramic.[2]  Reinforcement with kaolin has an advantage over other techniques proposed to make textile tube and yoke corselets in that such clay was often a component of the bleaching process of linen garments.  A clear evolution of the armor from incompletely rinsed white linen is thus easy to envision.  The tube and yoke became popular at Athens not long before the appearance of white-ground pottery, perhaps reflecting an increase in imports of fine kaolin for a variety of tasks.  The intercalation of kaolin clay unambiguously improved the ability of linen to resist the razor-tipped arrows.  These results in no way prove that hoplites made use of the properties of non-Newtonian fluid physics to make their armor more resistant; all the same, they do suggest a provocative new course for our study.  Our only source for the exact appearance of the tube and yoke comes from images on vases, so perhaps it is fitting that the culture that made this pottery famous spread its influence not by ranks of bronze, but rather by rows of clay.

[Patrick Waterson]

And here is a study which demonstrates just that.

Not sure if it is the one Paul means.

[PMBardunias]

Patrick, based on that study and a few others, I had an idea that this might work. I made up some clay impregnated linen panels and shotbthem with arrows. It does greatly increase resistance to fast moving projectiles. The hardest part was making it with period apropriate materials.  Modern manufacturers use glycerol, which was not available to the ancients. I tested reduced wine, honey, and pectin. The combination of kaolin and pectin is probably familiar under the name kaopectate.

As a benefit, modern armies use kaolin to stop bleeding.

This is one of those things like glued linen, where the fact that it works does not prove they did it.  But I like the idea that the evolution of the process may have arisen from using kaolin in the fulling and dyeing process.

[Patrick Waterson]

That is very interesting, Paul: I wonder if it will lead to a reappraisal of the 'linothorax'.

[PMBardunias]

It does make any thickness of linen more protective- specifically to arrows because it only works for fast impacts.  It could explain the spread of the linothorax at the time of the exposure to eastern archery.  But, I am acutely aware we need some scrap of empirical evidence for this to be anything more than a just-so story. Sure, I have as much evidence as we do the use of glued linen, but, that means I have as little evidence as the use of glued linen.

[Duncan Head]

Well....

- As Paul says, there is very little evidence. In fact the Ailian passage is I think the only reference to "argilos" in connection with armour, which suggests it might be referring to something distinctive and unusual, not something as common as the so-called "linothorax";
- And the so-called "linothorax" in art is not always white, which may also suggest that kaolin was not a standard part of its construction (though it's always possible that the white ones are linen and the coloured ones are leather?).

However, one of the rare surviving possible fragments of linen armour I know of, the Masada possible-pteruges, has an interesting description:

Where this fragment retains its original surface, it is very flat, as if pressed or polished ... and some kind of additional material appears to have been rubbed into it, this new material now appearing whitish and powdery.

Could it be kaolin?

[PMBardunias]

Thanks Duncan.  Kaolin need not be white. Most women's face powder is primarily high grade kaolin (or Bentonite clay, which you have to avoid if you try this at home because it does not shear thicken the same way).  If pigment would in any way alter the performance I do not know.  T-Ys of leather could be the colored ones we see.  I long ago suggested alum tawed leather specfically, and alum is a mordant used in dyeing. So lots of opportunity for cross over in existing processes and materials.

I asked Gleba once if that powder could be kaolin, but she did not know.  I did not say why because I had not published the experiments in my book yet, so maybe I should try again.  The other problem is gesso.  For example, we have surviving aspis facings that have white powder residue.  This has been described as gesso, but if you do not know what kaolin does, that would be the obvious answer.  Also, they could be kaolin impregnated AND gesso coated.  If anyone wants to chase down further information, you have my blessing since I have published the concept. I would ask   please keep me in the loop.

In 2021, I have a slew of tests of many hoplite things planned.  A friend of mine with some of the most accurate Persian arrowheads I have seen will shoot some patches of treated linen for me. I will probably start a little contest, where people bring their favorite linen or leather treatments for resistance testing.

[Justin Swanton]

It's good to see a serious academic thread on the use and usability of plastic armour evolve into a serious academic study of the use and usability of kaolin as armour reinforcement.

I would like to add this link that gives a study of the capacities of reinforced plastic used as ballistic armour with reference to its possible use as body protection in 2000BC. 

[Patrick Waterson]

I would like to add this link that gives a study of the capacities of reinforced plastic used as ballistic armour with reference to its possible use as body protection in 2000BC. 

Which all goes to show that many a true word is spoken in jest.

Kaolin actually seems to be a viable armour reinforcement material, particularly against arrows.  As Paul points out, the fact that it works does not prove that it was actually done, but we are finding clues which are mounting up to suggest it as a strong possibility.

[PMBardunias]

It's good to see a serious academic thread on the use and usability of plastic armour evolve into a serious academic study of the use and usability of kaolin as armour reinforcement.

I would like to add this link that gives a study of the capacities of reinforced plastic used as ballistic armour with reference to its possible use as body protection in 2000BC. 

My apologies for the unintentional hijack.  My French is not what it used to be, I cannot find the description in what you linked to. Can you cut and paste it here?

I do wonder, having not seen it, if the plymer was used to coat an organic backing, or if they were solid.  The first commercial plastics were found while looking for artificial shellack if I recall. Plastics like Bakelite are very brittle for armor use.

[Justin Swanton]

It's good to see a serious academic thread on the use and usability of plastic armour evolve into a serious academic study of the use and usability of kaolin as armour reinforcement.

I would like to add this link that gives a study of the capacities of reinforced plastic used as ballistic armour with reference to its possible use as body protection in 2000BC. 

My apologies for the unintentional hijack.  My French is not what it used to be, I cannot find the description in what you linked to. Can you cut and paste it here?

I do wonder, having not seen it, if the plymer was used to coat an organic backing, or if they were solid.  The first commercial plastics were found while looking for artificial shellack if I recall. Plastics like Bakelite are very brittle for armor use.

I draw your attention to the date the thread was created....

[Erpingham]

Pointing it to a French article was clever.  It could have had something tucked away in it that wasn't immediately obvious, if your French isn't too hot, like mine.

[Duncan Head]

For example, we have surviving aspis facings that have white powder residue. 

Really? I don't think I've come across this - do you have references to hand?