Eri is often described as the wool of the silks, and the measurements bear that out. It is coarser and weaker than mulberry but stretches further, absorbs more moisture and has a far lower initial modulus — which is exactly the combination that produces a soft, wool-like handle rather than a crisp one.
Eri against mulberry
| Property | Eri silk | Mulberry silk |
|---|---|---|
| Density (g/cm³) | 1.31 | 1.34 |
| Fineness (dtex) | 3.34 – 4.44 | 2.22 – 3.33 |
| Tenacity (cN/tex) | 27.43 | 37.17 |
| Initial modulus (cN/tex) | 230.09 | 814.15 |
| Elongation at break (%) | 22 | 19 |
| Moisture regain (%) | 10.12 | 9 |
| Degumming loss (%) | 13 – 16 | 20 – 22 |
Structure and composition
- Roughly triangular cross-section with few striations. Surface pores and voids give a specific heat capacity of 1.38 J/gK — the basis of eri’s thermal performance. It insulates better than wool and is more comfortable than cotton because of its moisture absorption.
- After degumming, over 80 % fibroin across twenty amino acids, alanine at 40 % and glycine at 25 %, with higher proportions of acidic (aspartic, glutamic) and basic (arginine, histidine, lysine) residues than mulberry.
- Lustre exceeds cotton through translucency and uniform cross-sectional area, but does not match mulberry.
- Low initial modulus against mulberry explains the soft, wool-like handle and the fabric’s tendency to soften further with wear.