Silk and satin

• Silk warms quickly to the hand and holds that warmth. Polyester satin stays cool and slightly slick.
• Silk has an uneven, subtle lustre that shifts with the angle. Polyester satin has a more uniform, glassy shine.
• Crushed in the fist, silk creases softly and the creases fall out. Polyester satin creases sharply or barely at all.
• Silk absorbs moisture readily. A drop of water on polyester satin tends to sit on the surface.

Momme, written mm, is the weight unit used for silk, describing the weight of a fixed area of fabric. Lightweight silk for a camisole sits at the lower end of the range and a heavier silk for a slip in the middle. Higher momme means a denser, more durable, more opaque and more drapey fabric.

Silk is a fine, smooth filament, so a silk surface presents very little friction against skin. It absorbs a meaningful amount of moisture without feeling wet, and it behaves adaptively in temperature: cool against warm skin, insulating in a cold room. For a slip worn between skin and a lined dress, that combination is close to ideal.

It is also the wrong material for anything that needs to stretch. Silk has almost no elastic recovery, which is why silk garments are cut on the bias to borrow stretch from the geometry of the weave rather than the fibre. A bias cut slip drapes and moves with the body; a straight cut one does not.

Silk is a protein. Anything that would damage hair, meaning heat, alkali, bleach and enzymes, will damage silk in the same way and for the same reason.

1. Use cool water, no warmer than 30 degrees. Heat sets creases and dulls the surface.
2. Use a detergent formulated for wool or silk. It will be pH neutral or mildly acidic and free of protease enzymes, which digest protein fibres.
3. Never use chlorine bleach or oxygen bleach, and avoid detergents containing optical brighteners, which build up and grey the fabric.
4. Move the garment gently through the water for a few minutes. Do not rub or wring.
5. Rinse thoroughly. A final rinse with a small amount of white vinegar neutralises alkaline residue and restores some shine.
6. Roll in a towel to remove water, then dry flat, out of sunlight. Ultraviolet light yellows and weakens silk.

Antiperspirant deposits and body oils are the usual cause of yellowing under the arms in a silk camisole, and they set with time and heat. Washing promptly after wear is far more effective than any treatment applied later.

Polyester satin is far more tolerant: cool machine wash in a bag, mild detergent, low spin, dry flat or on a hanger. Its weak points are different. It picks up and holds oily soil, which is why a synthetic satin can hold an odour after a normal wash when a silk one does not. A slightly warmer wash, around 40 degrees, and a detergent with some surfactant strength deals with that, provided the garment has no elastane content that would object.

Polyester satin is also thermoplastic: an iron above its softening range will glaze the surface permanently. Use the lowest setting, press from the reverse and use a cloth between the iron and the fabric.

A satin weave floats long threads across the surface, which is precisely what makes it smooth and precisely what makes it easy to snag. Rings, watch clasps, rough nails and velcro are the usual culprits. A pulled thread in satin should be worked back from the reverse with a blunt needle rather than cut, because cutting releases the float and opens a hole.

Storage matters more than it does for knits. Hang silk on a padded hanger or fold it loosely with acid free tissue; long term folding under weight sets a permanent crease line at the fold. Drying and storing covers the rest of the drawer.