I’ve been asked which yarn I would choose for a wrap that is soft on the shoulders but strong enough to support a growing toddler. So I made a list of factors influencing the quality of your wrap based on the quality of the yarn/fibre.
Abrasion resistance based on type of fibre, from good to poor: nylon, linen, acrylic, cotton, wool (coarse), silk, wool (fine), rayon.
Pilling resistance based on type of fibre, from good to poor: silk, flax, cotton, wool, acrylic, polyester, nylon.
Abrasion and pilling resistance based on quality of yarn, from good to poor: worsted and long-stapled (long fibres that have been combed and then spun), woolen and short-stapled (short fibres that have been carded and then spun).
Strength (resistance to breaking/tearing) based on fibre, from strongest to weakest: flax, hemp, silk, nylon, polyester, wool (coarse), cotton, acrylic, wool (fine), rayon.
Elasticity (the ability to stretch without breaking) based on type of fibre, from higher to lower: wool, silk, rayon, cotton, ramie, flax/linen.
The number of spun strands of yarn that are plied together is another factor determining strength and resistance to pilling and abrasion.
A: 2-ply Cottolin (60% cotton, 40% linen; 6000 m/kg); B:4-ply Yak (70% extra fine merino, 30% yak; 5000 m/kg; worsted spun); C: 4-ply Seidenstrasse (65% extra fine merino, 35% mulberry silk; 4000 m/kg; worsted spun); D:6-ply Kimono (54% extra fine worsted spun merino, 46% reeled mulberry silk, each of the three strands of spun merino is plied with one strand of reeled silk; 3000 m/kg).
Strength from good to poor: Kimono, Seidenstrasse, Yak, Cottolin.
If you are looking for a yarn with high elasticity, strength, and resistance to abrasion and pilling, a yarn that will make a soft but strong baby wrap when woven correctly, your best options are: silk and silk blends, worsted-spun wool and wool blend yarns, as well as long-staple cotton and linen and their blends.
Rayons have a poor abrasion resistance and a low breaking/tearing point compared to high-quality silk, wool, and cotton. The production process of rayons is an environmental disaster, because highly toxic substances such as carbon disulfite are used. You won’t find rayon in my yarn stash. The processes of manufacturing Lyocell and Tencel, though, are environmentally benign. Lyocell and Tencel are stronger than any other cellulose-based synthetic fibres, especially when wet.