Real Deal Spolas

[Crispianus]

The scale armour in Tut's tomb was most likely oil tanned. The black goo that was found on the armour is what happens when oil-cured hide deteriorates.

Hulit said it was translucent, i.e. light could pass through it. Tanning oil or veg creates an interlocking fibrous network that is opaque.  I suspect the goo was just just rawhide scales that had broken down in addition to some protective shiny coating that was probably oil based.  In Homer the oil must be worked into the hide by manually bending the leather until the oil is worked into it, also made it soft.Tut's scales are also painted red on one side;  no period paint would stick to oil tan --I don't even think acrylic would.  the red paint would need to be sealed along with the hide or it would stain things.

I do believe the goo is gelatine...

I think there is some suggestion that the egytians used castor/sesame oil for producing their leather, they dont seem to have been particularly enamoured of adopting new ideas in regard to tanning/tawing probarbly because of the dry environment, but there may well be other factors involved commercial/traditional etc.

Leather Work in Ancient Egypt, Veldmiejer 2014

Amosis (Amasis Pharoah) is said by Herodotus to have donated what amounts to a boat load of Alum to the Delphians to help rebuild their temple so it seems to have been available in large quantitys in 6th century egypt, but of course there are many uses for Alum: dying, tawing , medicine , trade etc. as well as the Greeks being able to dispose of large quantitys, but it may just be a case of "beggers can't be choosers".

Theophrastus he of the veg tan references (a very prolific author it seems) apparantly wrote a book specifically on salts and Alum ("Of Salt, Nitre and Alum") but unfortunatly it doesn't seem to have survived (to my Knowledge), but maybe Pliny read it, I think its quite likely?

I think every method of producing "leather" requires manual/mechanical manipulation in some form and often quite a lot, hammering seems to be a very ancient method of getting oil into the skins/hides.
Some thoughts