The Ichorcloth Cowl is an armor added by Thaumic Tinkerer. It is worn in the helmet slot and it has the same protection value as the Diamond Helmet but it is unbreakable. It is also resistant to fall damage (but does not negates it completely) and has 4% vis discount.
You have found how to weave ichorcloth into clothing. These new clothes are about as effective as mundane diamond armor, when it comes to protecting the wearer from damage. However, this cloth is completely unbreakable and will never sustain as much as a scratch.