How to wash a silk pillowcase - Silk care guide NZ - The ultimate guide

Silk has a reputation for being difficult. It isn't, really. It just asks for a gentler hand than the rest of your laundry, and once you understand why, the rules more or less explain themselves.

Here is the short version, if you are standing at the machine right now. Wash silk in cool water, on its own, with a small amount of pH-neutral detergent. No bleach, no fabric softener, no tumble dryer, no direct sun. Line dry in the shade and iron low if you must. That is genuinely most of it.

Why silk is fussier than cotton

Silk is a protein, not a plant. Each thread is mostly fibroin, a fibre built from eighteen amino acids. That structure is why it feels closer to skin and hair than to a tea towel. The protein is also its weak spot. Ordinary laundry detergents are alkaline, and silk's proteins begin to break down in alkaline water. The research is blunt about it. A standard high-pH detergent can degrade silk's proteins by around 30% in a single wash, and water hotter than 40°C raises the risk of the fibres fracturing by more than a quarter. Heat and harsh detergent do not just fade silk. They quietly take it apart. Conservators who look after museum textiles wash protein fibres in slightly acidic, near-neutral solutions for exactly this reason.

So the rules are not fussiness for its own sake. Cool water and a gentle detergent keep the fibroin intact, which keeps the shine, the strength and the slip you paid for. If you are curious why a higher-grade silk copes better with washing in the first place, that comes down to silk momme, the weight and density of the weave.

How to hand-wash silk (the safest way)

Hand-washing is gentlest, and for scarves, camisoles and eye masks it is the one to default to.

1. Fill a basin with cool water, just below 30°C, so it feels barely cool on your wrist.
2. Add a little pH-neutral or silk-specific detergent and swirl it through.
3. Submerge the silk and move it gently for a few minutes. Do not scrub, twist or wring.
4. Rinse in fresh cool water until it runs clear.
5. Press the water out between your palms, or roll the piece in a towel. Never wring.
6. Lay flat or hang in the shade to dry.

How to machine-wash silk (when you would rather not)

Our mulberry silk pillowcases are woven tightly enough to take a careful machine wash, which is the small luxury of a higher-grade silk. Garments and finer accessories are better off hand-washed.

1. Turn the item inside out and zip it into a mesh wash bag so it cannot snag or stretch.
2. Run the delicate or hand-wash cycle, cold, below 30°C.
3. Use a pH-neutral or delicate detergent, a capful rather than a scoop.
4. Skip the fabric softener, bleach and tumble dryer entirely.
5. Lift it out promptly and dry away from heat.

Drying and ironing

Sun and heat are silk's two enemies at the finish line. Line dry in the shade. Direct New Zealand sun will dull the colour faster than you would think, even in winter. If a piece needs pressing, iron on the lowest silk setting while it is still slightly damp, ideally through a cotton cloth, or use a steamer and let the creases fall out on their own.

Caring for different silk pieces

Pillowcases handle a gentle machine cycle in a wash bag. Silk scarves, camisoles and slip dresses prefer hand-washing and a flat dry so they keep their shape. Scrunchies, eye masks and face coverings are quick to hand-wash and dry overnight. The fabric is the same protein in every case, so the same gentle logic applies. You are simply scaling the care to the piece.

The mistakes that quietly ruin silk

Most silk does not die in one dramatic accident. It wears out from small, repeated habits. The usual culprits:

• Hot water.
• "Bio" or enzyme detergents. Those enzymes are designed to digest protein, which is precisely what silk is.
• Fabric softener, which coats the fibres and kills the shine.
• Wringing, which stretches the weave.
• The tumble dryer.
• Drying in full sun.

Avoid those six and a good silk pillowcase will outlast far more than you would expect.

A gentle touch, rewarded

Silk asks for cool water, a kind detergent and a little patience. Give it that and it gives years back. For a fabric this good against your skin, that feels like a fair trade.

Source: Royal Society of Chemistry, Textile conservation, on silk as a protein fibre and the effect of pH and heat on fibroin.