Why has my silk gone yellow or marked with water spots?

Silk yellows from perspiration, from sunlight and from age, and it water-spots because the fibre swells locally. Each has a different cause and only some of them can be reversed.

Difficulty: intermediate
Time: 20 min
Read: 4 min
Safety: caution

Short answer

Yellowing under the arms and at the collar is perspiration that has oxidised into the protein — treat early with a cool soak and an acid rinse, because once it has set it is effectively a dye. Overall yellowing is sunlight or age and cannot be reversed. Water spots are local swelling and a shifted finish, and the fix is to damp the entire panel evenly rather than the spot. Never chlorine bleach, never biological detergent.

Silk is a protein filament produced by the silkworm, and almost everything that goes wrong with it comes from that protein chemistry. Understanding which of the four common problems you have decides whether the garment is recoverable, because two of them are and two are not.

Safety

Never put chlorine bleach on silk under any circumstances. Silk is a protein fibre and chlorine destroys it, turning it yellow and then rotting it to holes. The same applies to biological detergent, whose enzymes digest the fibre. Both types of damage are immediate and cannot be undone.

Step by step

Identify which yellowing you have.Localised at the underarms, collar or waistband is perspiration. Even across the whole garment, and worse where it was exposed, is light. Yellow along fold lines on a stored item is oxidation, often accelerated by acid from a cardboard box or by residual body oil. The three need different responses.
Treat perspiration yellowing early.Sweat is initially slightly acidic and becomes alkaline as it degrades, and alkali is what damages silk. Soak the garment in cool water with a silk or wool detergent, then rinse with a splash of white vinegar to bring the pH back down. Do this while the mark is fresh.
Accept the limits on set perspiration stains.Once the mark has been through heat — a warm wash, an iron, a hot car — the protein has cross-linked and it is bonded into the fibre. No safe treatment removes it. Attempting to bleach it will destroy the silk before it lightens the mark.
Understand light yellowing.Ultraviolet degrades silk protein and breaks the fibre down. The yellowing is the visible symptom of the fibre weakening, so a sun-yellowed silk is also structurally weaker. It is permanent, and the garment should be kept out of light from now on.
Deal with a water spot the right way.The mark is a ring where the fibre swelled and the finish moved outward. Spot cleaning makes another ring. Instead, damp the entire panel evenly — a fine spray or a steamer held away from the fabric — then let it dry flat and evenly, and press from the reverse through a cloth while barely damp.
Wash the garment correctly from now on.Cool water, a silk or wool detergent, no rubbing, a vinegar rinse to restore the sheen, roll in a towel, dry flat away from sun and heat, and iron damp on the coolest setting from the reverse.
Store it out of harm.Wrapped in acid-free tissue, in a breathable cotton bag, away from light, and never against untreated cardboard or wood. Both give off acids that yellow protein fibre over months.

Tips

Antiperspirant is a bigger cause of silk yellowing than sweat itself: aluminium salts bind into the fibre and set. Let antiperspirant dry fully before dressing, and consider dress shields on anything valuable.
Hairspray and perfume both contain alcohol and can leave permanent marks on silk. Dress last.
A vinegar rinse is not a folk remedy here — silk is happiest slightly acidic, and it restores the light-scattering surface that gives the sheen.
Oxygen bleach is far gentler than chlorine but is still alkaline and still risky on silk. If you use it at all, use a very weak solution, cool, briefly, and test on a hidden seam allowance first.
Dupion, shantung and other textured silks water-spot far more readily than smooth crepe de chine or habotai.

If it doesn't work

Yellow crust under the arms

Cause: Antiperspirant aluminium bound with sweat protein into the silk — Fix: Cool soak with a silk detergent, then an acid rinse. Treat before any heat touches it. Once set it is permanent, so prevention with dress shields is the real answer.

Ring-shaped water mark

Cause: Local fibre swelling and a displaced finish at the edge of the wet area — Fix: Damp the whole panel evenly, dry flat, then press barely damp from the reverse through a pressing cloth.

Overall dull yellow tone

Cause: UV degradation of the silk protein, or long storage in acidic conditions — Fix: Not reversible. Keep it out of light and store it in acid-free tissue to stop it progressing.

Silk gone limp and lost its rustle

Cause: Alkaline detergent or hot water has stripped the sericin and damaged the surface — Fix: A vinegar rinse restores some sheen. The handle does not fully return — switch to a silk-specific detergent.

Small holes appearing with no moth evidence

Cause: Chlorine exposure, from bleach, a swimming pool or heavily chlorinated water, or advanced UV damage — Fix: Not repairable as fabric damage. Stop all chlorine exposure; the holes will keep appearing where the fibre has been weakened.

Questions people ask

Can I use lemon juice on silk?

A very dilute acid rinse is safe and beneficial, but neat lemon juice is strong enough to strip dye and is often used with sunlight, which is the worst thing for silk. Use white vinegar in the rinse water instead.

Will dry cleaning remove silk yellowing?

Sometimes, on fresh perspiration marks, and rarely on set ones. Tell the cleaner what the mark is — treating a protein stain as a general soil makes it worse.

Is washable silk different?

Yes. It has been treated or woven so the surface tolerates water without spotting. It still wants cool water, a silk detergent and no rubbing.

Why did my silk go stiff after washing?

Usually detergent residue, or drying in direct heat. Rinse thoroughly with a little vinegar, and dry flat away from any heat source.