Fibre · Bombyx mori, one continuous filament
Silk
The only natural filament fibre, measured in momme, ruined by sunlight and by the deodorant you put on before the blouse.
Why filament changes everything
Cotton, wool and cashmere are staple fibres, short lengths spun together with ends everywhere. Silk is a filament, a single continuous strand, which is why it has no fuzz, why it reflects light in a line rather than a scatter, and why it feels cool: there are no fibre ends to trap air against the skin.
It is also why damage is different. A staple yarn wears gradually as fibres work loose. A filament either holds or it snags, and a snag in silk is a pulled loop that cannot be worked back in. Rings, watch bracelets and rough fingernails do more damage to silk in a year than wear does in a decade.
The two things that destroy it
Sunlight breaks the peptide bonds in the protein and does it faster than in any other common fibre. A silk curtain in a south facing window has a life measured in a few years, and it fails by going brittle and splitting along the fold lines rather than by fading, though it does that too.
The second is alkaline chemistry and salt. Antiperspirant, which is acidic and aluminium based, and sweat, which is salty, both attack silk at the underarm, and the damage is cumulative and invisible until the fabric splits. This is the single most common way a good silk blouse dies. Dress after the antiperspirant is completely dry, and wash after every second wearing rather than waiting for a visible mark.
Peace silk, and what it means
Conventional production kills the pupa inside the cocoon so that the filament can be unwound unbroken. Peace or ahimsa silk lets the moth emerge, which breaks the filament into short lengths that then have to be spun like a staple fibre. The result is a fabric with a softer, more matte, slightly irregular hand. It is a genuine ethical difference and a genuine change in the material, not a like for like substitute.
Momme weight
Momme is the weight of 100 yards of 45 inch fabric in pounds. It is the one number worth reading.
How to check it
- Check the momme weight. If a seller cannot tell you, they are selling on the word silk alone.
- Hold it up. Real silk has an uneven, shifting lustre. Polyester satin has a flat, uniform shine that reads as plastic in daylight.
- Crush a corner in your fist and release. Silk springs back with soft creases, polyester barely creases and cheap viscose stays crumpled.
- Look at the seams inside. Silk frays fast, so a good garment has bound or French seams rather than an overlocked edge.
Care
- Wash cool by hand with a pH neutral or silk detergent. Never biological detergent, whose enzymes digest protein.
- A tablespoon of white vinegar in the final rinse restores lustre by neutralising detergent residue.
- Roll in a towel rather than wringing. Silk loses a third of its strength wet.
- Iron damp, on the reverse, at the silk setting. Water spots on dry silk are difficult to remove.
- Store out of light, folded with acid free tissue at the folds, never in plastic.