Testing casein paint on leather, part III

Dammit.

Our test board cured for an entire month.  Last week I added some thin layers of carnauba wax paste, which is, admittedly, not something that would've been available at the time (carnauba palms are native to Brazil), but I was attracted to the fact that it's harder than beeswax and has a higher melting point.  It's difficult to see, but on some of the swatches it dried to a whitish waxy appearance.  At this point, my favorite was the glue-soaked, sanded leather with a wax topcoat and no gesso (lower right corner), which was smooth and a bit glossy.

I wanted to first test the paint against rough surfaces and sharp implements to see if it would flake.  It didn't, though the knife and half brick scuffed the paint applied over unglued leather badly.  The glued/sanded/waxed/un-gessoed swatch looked to be the most durable, as both implements glided over it leaving superficial scratches.

The real test, of course, would be the rain.  I waited until today when it was convenient to set the board outside for an hour, as I figure these are realistic conditions.

In the meantime, I cut up a whole bunch of undyed, semi-bleached linen swatches, as I figure these would be the most likely to show paint smudges if someone's clothing were to come into contact with wet paint.  When the board came inside, I rubbed one swatch of linen against each swatch of paint.

At this point, it became difficult to read the labels, but that didn't matter.  NONE of the paint swatches adhered well enough for practical use; each one smudged badly onto the linen.

Sadly, the glue-soaked but un-gessoed swatches fared by far the worst, as the glue absorbed water and turned liquid.  The paint slid right off of them.  The gessoed ones didn't do much better.  The wax topcoats gave no noticeable protection.  In fact, the leather swatch with no treatment at all (corresponding to the linen at the bottom of the leftmost column) did best - or, at least, least worst - although as you can see, it still smudged.

So where do we go from here?
The thing is that milk paint is normally applied to raw wood, and it's said to be durable in this application, particularly if coated with a drying oil.  This leaves us with several options:
1)  Bare wood scabbards with only a drying oil or wax finish.
2)  Painted wood, again probably having a water-resistant finish.
3)  Unpainted leather facings, perhaps vat-dyed in a single color (I am told that a finish of beeswax and drying oil will prevent dye bleeding, but that's a question for another day).
4)  Embossed sheet metal facings, either over a leather facing or glued directly to the wood.
5)  Oil paint or encaustic (wax).  Unfortunately, I know of no evidence that these types were used in our period.

The first two leave us with the issue of the scabbard possibly splitting along the seams when the blade is pushed in or jostles inside the scabbard while the wearer is running.  Only the chape would provide reinforcement.  It's possible that small bands of organic material such as rawhide were tied or stitched around the scabbard farther up, leaving most of the wood bare for painting, but that's pure speculation.

Options 3 and 4 have good historical grounding, as the Issyk Golden Man's scabbard was covered largely with leather and small sheet gold adornments, while the Achaemenid scabbard from Egypt had a (now-vanished) gold facing pasted to the wood.  We're still left between a rock and a hard place:  Most reenactors won't have the skills, or money to pay someone who does have the skills, to make a full metal facing, since fitting one to the complex curves of a wooden core in the classic Achaemenid shape would require lots of careful hammering to expand the metal in certain areas.  On the other hand, leather alone is pretty dull-looking, and I've never seen evidence for Achaemenid scabbards with partial metal plates such as those at Issyk which would be easier to make.

I'll look into carrying out milk paint tests directly on wood.  In the meantime, Ivor at RAT brought to my attention the book Chariots in Ancient Egypt, which is said to have some evidence for painted leather.  Now I have a few more weeks of free time before the spring semester starts, I can finally start checking whether it contains anything potentially applicable to our situation.