
Silk: The Biology of the Protein Fiber
What is Silk?
Silk is a natural protein fiber, primarily composed of Fibroin, produced by the larvae of the mulberry silkworm (Bombyx mori) to form its cocoon. Unlike plant fibers (Cotton, Linen) which are cellulose-based, silk is animal-based, sharing a similar chemical structure to human skin.
1. The Amino Acid Structure
Silk is composed of 18 different amino acids. Its protein structure allows it to be biocompatible.
- Skin Affinity: Because its composition closely mirrors human skin/hair, silk does not draw moisture out of the skin (unlike cotton). It helps maintain the skin's natural hydration barrier.
- Hypoallergenic: The sericin protein naturally repels dust mites, mold, and fungus, making it the ideal textile for asthma sufferers or those with allergies.
2. Thermal Regulation
Silk has a unique "paradoxical" thermal property.
- Insulation: The microscopic structure of the silk fiber is triangular and prism-like. This allows it to trap a layer of warm air close to the body in winter.
- Breathability: In summer, its high absorptivity allows it to wick moisture away efficiently, keeping the skin cool. It acts as a natural temperature regulator.
3. Tensile Strength
Despite its delicate appearance, a single filament of silk is stronger than a filament of steel of the same diameter. It has high elasticity and can stretch up to 20% beyond its original length without breaking. However, it loses up to 20% of its strength when wet, which is why care must be taken during washing.
4. The Look (Refraction)
The shimmering appearance of silk is not a chemical finish; it is structural. The triangular prism-like structure of the silk fiber refracts incoming light at different angles, producing distinct colors and a natural luster.
5. Environmental Biodegradability
As a natural protein, pure silk is 100% biodegradable. When disposed of, it decomposes naturally into the soil, acting as a fertilizer (nitrogen source), unlike synthetic alternatives like Polyester Satin which will persist in landfills for centuries.
Conclusion
Silk is more than a luxury aesthetic; it is a biological tool. Its protein-based structure offers unique dermatological benefits, thermal regulation, and incredible strength, making it one of the most sophisticated materials in nature.


