How to get sweat stains out of a wool sweater

03 Before you start

• Use white cloths or paper towels only: coloured ones can transfer their own dye into a wool sweater.
• If the label says dry clean only, do not use this home washing method: take it to a professional. For washable delicates, use a product specifically labelled for the fabric.
• Pretest every permitted treatment on an inconspicuous area, including trims, and let it dry. Stop for colour transfer, lightening, rings, stiffness or distortion. A successful spot test does not guarantee the whole item is safe.

05 Dried, set, or back again?

• For a dried stain, use only a detergent specifically labelled for this fabric, at its stated dilution and contact time, and only if the care label permits washing. Do not substitute ordinary enzyme detergent on wool or silk. If it persists, consult a professional rather than increasing the strength or soaking time.
• Old oil has partly oxidised and gone sticky; apply the degreasing step two or three times, and give powder an overnight stay where it is used.
• Do not use ordinary protein-digesting enzyme products on wool or silk. A fabric-approved wash or a professional cleaner is the next step; repeated treatments may damage dyes or fibres.

Oil is often invisible on damp fabric and shows again once dry. Check in daylight after air-drying and repeat the degreasing step before any heat.

Clean according to the care label and dry fully before storage. Do not add an extra enzyme treatment or prolonged soak merely because an item will be stored.

06 What sweat stains is made of

• Protein
• Oil and fat
• Minerals and metal
• Dye

Sweat stains can include protein. Heat can make protein-containing stains harder to remove. On washable materials, cool water is a common first step. A protein-digesting detergent is an option only when its label permits the actual fabric; use a suitable delicate-fabric detergent on wool or silk.

The oily part of sweat stains will not dissolve in water at all. It needs a surfactant such as dish soap, or a solvent, to break it up, and a dry powder can draw fresh oil out before you start.

Sweat stains may leave inorganic salts or mineral residue. Treatment depends on the actual deposit and surface; not every mineral dissolves in a mild acid, and acids damage calcareous stone.

Sweat stains carries dye that soaks into fibres rather than sitting on them. Depending on the dye, alcohol dissolves it, oxygen bleach breaks it down, or sunlight fades it, and speed matters more than strength.

• Fresh sweat is nearly clear. The yellow comes from aluminium in antiperspirant reacting with sweat proteins and skin oils over many washes.
• Chlorine bleach reacts with those proteins and makes the yellow worse.
• Collar rings are skin oil, not sweat, and need a degreaser such as dish soap, not just detergent.

07 The material: wool and cashmere

A wool sweater can be wetted, but gently: dab, swish and press, never wring or scrub.

No rubbing at all; every step is a press-and-lift.

Soak only if the garment and fabric-specific detergent labels permit it, using their dilution and contact time. Ordinary enzyme detergent and alkaline oxygen-bleach powder are not substitutes for a wool- or silk-compatible wash.

Water stays at or below 30 °C (86 °F) the whole way through.

What this file leaves out because of the material:

• Enzyme ("bio") detergent. Protease enzymes digest protein, and wool is protein. Use an enzyme-free wool wash.
• Oxygen bleach (OxiClean-type powder). Alkaline peroxide damages wool, cashmere and silk; the packs say so.

• Wool is keratin, the same protein as hair, so enzyme detergents that digest protein stains also digest wool.
• Wool fibres have overlapping scales; heat plus rubbing locks them together, which is felting, and it cannot be undone.

The wool and cashmere file rates every common cleaner for it.

08 Next time

Use antiperspirant at night rather than just before dressing, let it dry, and wash shirts promptly instead of letting sweat sit for days.

09 Questions