A History of the Idea of Glued Linen Armour

[Flavivs Aetivs]

Sounds like another dodgy translation to me. What does it say in the original language?

Ἀυτὸς μέντοι ἄνευ θυρεοῦ τηνικαῦτα διηγωίζε, ἐκ δὲ
λίνου πεποιημένου οἴνῳ αὐστηρῷ ἱκανῶς ἡλισμένῳ διάβροχον πολλάκις
περιπτυχθὲν δίκην θώραπος ἐνδύετο· ἐς τοσοῦτον δ’ἦν αντιτυπὲς ἁλσὶ καὶ
οἴνῳ συμπιληθὲν ὡς καὶ βέλους εἶναι παντὸς στεγανώτερον· ἠριθμοῦντο
δʹεἰς ὀκτωκαίδεκα καὶ πλείω τὰ τοῦ ὑφάσματος συμπτύγματα·

What's missing from all of this is that the most common middle Byzantine-era wine was Retsina wine, which had significant amounts of pine resin dissolved in it. Like other manuscripts which mention using pitch or resin to harden gambesons, a mix of salt and the resin in the wine is probably what hardened Conrad of Montferrat's.

Evidence from the military manuals shows the Romans themselves used twining up through at least the end of the 10th century. And as Manning, Gleba, Granger-Taylor, etc. have pointed out, the evidence strongly suggests twining was the primary method used in the Classical Roman period and Greek/Hellenistic eras as well. Felting/Fulling, Wadding, and Quilting all seem to have been ad-hoc measures used in emergencies.