Tube and Yoke -How \"white\" was white?

[John Conyard]

The tube and yoke could be made in bright colours, but it is certain a good number were made in white.

But just how white was white?

I am attaching a photo of a roe deerskin which has been traditionally alum tanned, set against some pretty standard vegetable tanned leather, two samples of vegetable tanned leather made using alum, and a sheet of white paper.


[attachment=2237]004_2011-12-06.JPG[/attachment]


I am tempted to make a new tube and yoke in vegetable tanned leather whitened using alum. But the white colour is more of a dirty grey.

And it is very hard to harden this leather in to armour, or at least I haven't managed it yet! I can make the armour from several thicknesses of leather, but hardening helps it's defensive qualities. At least wetting the leather does not wash out the alum. So far.........

[Theodosius the Great]

Maybe you can use milk based white paint, like casein? The problem, I think, is that the paint will flake off in a short time. IIRC, Matt Amt suggests that applying oil (after the paint drys) helps prevent that.

~Theo

[Dan Howard]

Maybe the white ones were alum tawed and not painted at all?

[John Conyard]

Hi Dan,

I find it hard to believe the leather was painted.

I am not trying to drag up all the definitions of leather tanning once again. But the deer skin shown is alum-tanned leather, or tawed. Alum is mixed with salts and a variety of binders and protein sources, such as flour and egg yolk. Alum-tanned leather is technically "tawed" and not tanned, as the resulting material will rot in water. Very light shades of leather are possible using this process. The Hellenistic and Roman periods alum tawing would have been about the only form of mineral tannage available. Due to its poor resistance to water when not combined with other tannages such as oil, this leather would probably have been used more for indoors applications in temperate climes. Alum tawed leather is a poor choice for military applications (except perhaps in very dry climates) as the alum tends to be poorly fixed and is easily washed out if the leather becomes wet. Oiling the leather could help stop this. The Romans called tawed leather aluta. It seems to have been used occasionally for sails in later periods.Or so it says on our website!

The two thick leather samples are vegetable tanned using alum to whiten it. But both examples are more of a dirty grey than white.

[PMBardunias]

The Romans called tawed leather aluta. It seems to have been used occasionally for sails in later periods.Or so it says on our website!

I think some key information is missing in our discussion. From all I have read, and as you suggest, alum is unstable when wetted, but Julius Ceasar Bell Gall 3.13 wrote that the Gauls used aluta for their sails and alum tawed leather was evidently used to make uppers for shoes which must have been frequently exposed to water.

3.13.
For their ships were built and equipped after this manner. The keels were somewhat flatter than those of our ships, whereby they could more easily encounter the shallows and the ebbing of the tide: the prows were raised very high, and, in like manner the sterns were adapted to the force of the waves and storms [which they were formed to sustain]. The ships were built wholly of oak, and designed to endure any force and violence whatever; the benches which were made of planks a foot in breadth, were fastened by iron spikes of the thickness of a man's thumb; the anchors were secured fast by iron chains instead of cables, and for sails they used skins and thin dressed leather (pelles pro velis alutaeque tenuiter confectae). These [were used] either through their want of canvas and their ignorance of its application, or for this reason, which is more probable, that they thought that such storms of the ocean, and such violent gales of wind could not be resisted by sails, nor ships of such great burden be conveniently enough managed by them.

Some sort of tanning would seem to have been done in addition to the alum treatment. Maybe it is a matter of getting the process, and tanning agent, correct. Something that can tan but not darken the final product. Maybe a fat tan?

[richard robinson]

Having watched "rome wasn't built in a day" I have been toying with the idea of applying lime to some aspides i am making but having just used it to help slip the hair for the rawhide I am uncertain as to whether this will have a corrosive effect.
On time team I was fascinated with their heating ochre with vinegar to make Roman red while the Rome wasnt built in a day crew just went and added iron oxide.
The time team experiment made me wonder at the protective propertis of dirt - if this was the type of paint used to paint goathide clad shields. I personally have no problem with leather being painted (with ochres) as it is still used in Kenyan tourist shields to this day.

In Clan of the caveBear Ayla collected piss to bleach the leather white. Perhaps you could experiment with this bleaching technique as we know it was used on tgas etc...??? :lol:

I also still like the idea that leather and or linnen armours could be laquered/ sealed using the extract of squashed beatles as the technique was known to the egyptians.


Good Luck with your experiment Mr Conyard
regards
Richard Robinson

[John Conyard]

Oil could help water proof the leather, but it would also make it very flexible and soft. Good for sails and shoes, not so great for armour.

Mlk and cheese could help whiten leather, and also be used to glue several layers together into a laminated armour, an idea I like. But I still find a pure white vegetable tanned leather a hard idea to achieve.

[M. Demetrius]

Chalk dust rubbed into light leather?

Urine was/is used by Amerindians to help make the hair come off deerskins, etc. One technique is urine mixed with wood ashes, applied to the hair side, and the skin rolled up to "cure". I reckon they rinsed it before they softened the hide (often by chewing the leather). I've done some leather tanning. It's the most stinkin' wretched nasty work I've ever done. All past tense now.

[John Conyard]

It sounds like you guys are discussing buff leather,oil tanned leather, producing a buff coloured leather. Alum could be used to whiten it. From the Comitatus website,

The wet skin is oiled or greased, stretched and kneaded until moisture is lost and fat is absorbed. This is a very old process dating back to the first leather preparations. The brain tanning of the USA is linked to this, where brains and smoke were used the same way. There is a view that there is no Roman evidence for oil tanning, yet it
is perhaps the oldest method of leather preparation. In 17th century Europe marine oils were used,and some of the first machines used in tanning were made to help pummel the oil into the hide.

The hides were first soaked, often using lime, dried using sawdust and oatmeal, then oiled. Lime helps the quality of the oiled leather. The ancients may have used wood ash. The shales of North Yorkshire produced alum by large-scale chemical processing from the early 17th century. This is the origin of the white buff leather military belts. The wood ash, alum and lime opened up the fibres of the leather making it easier to oil. Back in classical times I suspect small skins could be oiled successfully without the use of alum or lime. But not large thick skins. There is a reference in Homer's Iliad where he compares the struggles between Greece and Troy to that of a man trying to stretch a huge cowhide soaked in lard. Evidence of liming dating back to Anglo Saxon
times suggests that medieval tanners were using liming to remove hair and open up the fibre structure and would have used this in their manufacture of oil tan buff leather.
Military buff leather can be seen as thick leather, usually between 3 to 5mm, which requires a heavy cattle hide. First of all the hide is washed and then treated with a liming solution which burns off the hair and swells up the hide. This allows the hide to more readily soak up the oils.

By the 18th century a band knife splitting machine was used to split the hide in uniform
thickness. Then the strongly alkaline lime residue was removed from the hide using acid salts. Before the oiling a samming machine like a mangle removed excess moisture. Then cod oil was used for the tanning, and beef tallow as a lubricant.

I am coming around to idea of full hides been made in to buff, and whitened in the process. But it is far easier to make vegetable tanned leather.

[PMBardunias]

But it is far easier to make vegetable tanned leather.

Now John, you know that the ancients did everything in the most difficult and arcane manner, specifically to foil future generations :-)

What "vegetable" are you using to tan the leather. I assume, perhaps wrongly, that it is the tannins in the product that are darkening the leather. I came across a reference for Sumac being used in conjunction with alum treated leather in Cordova for cordovan leather. Do you have any experience with this, perhaps the result is not as dark.

[richard robinson]

Wouldn't Sumac give a red colour and so the famous Cordova red leather?

regards
richard

[PMBardunias]

That could very well be. Perhaps it was not part of the tanning process at all, but I'm grasping at tenuous references.

I've seen some 17th century buff that was pretty white. White gloves as well. I'd like to see an oil/alum formula.