I´ve been searching throughout the internet for information about the weight of real leather and tissue (linen, cotton, etc.) body armour in the medieval period, but I can´t find any solid information about it.

There´s a lot of dubious and incomplete, or sourceless information... It seems that a linen gambeson, or cuir bouilli lamellar where excepcional, capable of resisting longbow arrowshots, being very lightweght...

There is an entire set of italian 13-15oz leather armour that is said to weight only 9 pounds and can hold against sword thrusts and arrows as much as maille... It´s hard to believe, because a leather motorcycle jacket can weight 6 pounds by itself and I dont´t believe that a hardened and much thick leather armour would weight less than a piece of cloth...

I believe that a heavy cotton, or linen gambeson (20 to 30 layers) can hold against bodkin arrows, but I couldn´t find any information about the weight of these armour too...

It seems odd, for if a combination of cuir bouilli and poirpont can be almost as tough as maille, and much lighter, I don´t know why someone would have such a huge work to build a maille...

hello Daniel
i can not help you with the weight of cloth, i can however help you with the leather armor part. ive recetly tested a pice of leather at 14oz thickness vs a small patch of rivited maille. suprisingly my 50lb long bow with armor piercing heads went clean through the maille, however the leather stoped the same arrow fiered from the same bow cold. i can however beleve the weight of that armor being only 9lb. im working on a breast and backplate of armor and right now all 3 pices together with buckels and straps cant weigh over 4.5 lb. i personaly think motercycel jackets are over heavy with all the padding and plates they have in it... or it might be the quality of the tanning process (oil tanned vs veg tanned)
i do know though that maille is more resistant to cuts and easer to fix then leather. if a pice of leather gets a cut in it, in order to properly fix your armor you have to replace the whole pice thats damaged.

for authentic armor i beleve each and every pice made would be drastically different from place to place.. or rather regon to regon.. southern briton may have leather armor made from cow hide ( it can be 13-15oz esaly) but leather from iceland or scandinavia would be out of elk buff, (10oz is what i think elk hide can get to) if you want to research different weights of leather i sugest going to a leather retailer like Tandy leather co. when i get my leather from them i normally get half a cow (im not exaggerating here) at a time and at a 14oz weight the box only weighs in at around 10-12 lb.
i do know that leather can stop a sword blow or stab.. and id trust a leather harness over my maille anyday now... id just hate to have to replace my breastplate every week from all the cuts and punctures on it... thats why i believe maille was so popular... its easy to fix and more durable then leather.. (although me being a fan of leather would wear a leather breastplate of a coat of maille :D )

cloth stoping arrows...i have heard of mongols wearing silk tunics under their armor in order to stop arrows that pierced their chain maille.... if what ive heard is true (and someone please tell me if they heard something simaler) id love to test it out with my long bow.