Paper armours of the Ming Dynasty

Qi Jia (緝甲, lit. 'Quilted armour') and Zhi Bi Shou (紙臂手, paper armguard)

Drawing of a Qi Jia, from 'Ji Xiao Xin Shu (《紀效新書》)'.

A helmet and a paper armguard, also from 'Ji Xiao Xin Shu (《紀效新書》)'.

Also known as Zhi Jia (紙甲, paper armour) and Ruan Jia (軟甲, soft armour), this armour is made of silk cloth stuffed with silk wadding and silk paper (paper made from silkworm cocoon) or normal paper to the thickness of one cun or more, then quilted with silk thread.  It can be worn as standalone armour, or underneath leather armour. For all intent and purpose, Qi Jia is the Chinese equivalent of gambeson.

Zhi Bi Shou is made of four layers of clothes stuffed with cotton and silk paper, then quilted with silk thread. Better quality version can be made with silk cloth and silk floss.

Sleeved paper armour (left) from 'Wu Bei Yao Lue (《武備要略》)'.

Qi Jia is usually sleeveless, although sleeved variant is not unheard of.

Zhi Jia (紙甲, paper armour)

A different type of Zhi Jia, hereafter dubbed "studded paper armour", is recorded in late Ming texts 'Jin Tang Jie Zhu Shi Er Chou (《金湯借箸十二籌》)' and 'Yong Chuang Xiao Pin (《湧幢小品》)'. It is made of flexible paper, hammered soft and layered to three cun thick, then fastened with studs. It is said that this armour performs better when soaked with rainwater.

Zhi Yi Jia (紙夷甲, lit. 'Barbarian-style paper armour')

Various components of Zhi Yi Jia, from 'Wu Bei Yao Lue (《武備要略》)'.

Zhi Yi Jia appears to be a two-piece version of paper armour. However, no other detail is known about this armour.

Chu Kai (楮鎧, mulberry armour)

Actual barkcloth armour is known as Chu Kai to differentiate it from ordinary paper armour. A Qing period source claims that Bai Gang Bing (白桿兵) were known to wear this type of armour.

Paper or Barkcloth?

Some have claimed that paper used in Chinese paper armour isn't really paper, but some kind of mulberry barkcloth. This is unlikely to be the case, as Chinese paper can be made from a variety of materials such as bamboo, rattan, wheatgrass, bulrush, flax, citrus and silk, not all of which can be turned into barkcloth.

When actual barkcloth was mentioned in Ming Dynasty records, it was always written as Pi (皮, skin), as tree bark is known as Shu Pi (樹皮, lit. 'Tree-skin') in Chinese language. An example can be found in Ben Cao Gang Mu (《本草綱目》, Compedium of Materia Medica):

『此即今構樹也。南人呼榖紙亦為楮紙。武陵人作榖皮衣。甚堅好。』
"This is known as Gou tree nowadays. Southerners also call Gu Paper as Chu Paper. People from Wuling make clothes out of Gu barkcloth, which are very tough." 

Note that Gou (構), Gu (榖) and Chu (楮) are different regional names for paper mulberry, while Zhi (紙, paper) and Pi (皮, skin or hide) are different terms used to distinguish true paper from barkcloth.

Another Northern Song Dynasty record also describes old accounting books being broken down to make more armours, again pointing to the use of actual paper rather than barkcloth.