Why Do My Curtains Smell Musty? Causes and Fixes

You walk into the bedroom and notice a stale, damp smell, and when you put your face near the curtains it is clearly coming from the fabric. Curtains hold on to smells because they are large, absorbent and rarely washed. In Singapore, where the air is humid and many bedrooms are closed with the aircon on for hours, a musty smell is one of the most common curtain complaints.

The kind of smell tells you a lot about the cause. Here is how to read it and what to do.

The three common curtain smells

A musty, damp smell

This is the most common. It means moisture is staying in the fabric long enough for mildew or mould to start growing, even if you cannot see any spots yet. It usually comes from:

• condensation on the glass after aircon, which the curtain absorbs where it touches or hangs close to the window
• a hem that sits on a damp floor or a wet sill
• curtains drawn back into tight bunches that never get air
• a room kept closed for long periods, such as a spare bedroom or a study

If you can also see black or grey dots, especially on the hem or the back of the lining, read our guide on why curtains get mouldy.

A wet dog or sour smell after washing

If the curtains smell worse after washing than before, they almost always dried too slowly. Heavy or lined curtains folded over a rack in a closed room can stay damp in the seams and hem for a day or more, and bacteria in the damp fabric produce that sour smell. Too much detergent, or a washing machine that itself smells, can add to it.

A chemical or plastic smell on new curtains

New curtains, especially blackout curtains with a coated back, can smell of chemicals or plastic when first unpacked. This comes from finishes used on the fabric and from being sealed in packaging. It usually fades within days to a couple of weeks with airing. If it is strong, air them well before hanging them in a bedroom.

How to get a musty smell out of curtains

1. Check the care label. Some fabrics must be dry cleaned, and some blackout coatings should not be machine washed.
2. Vacuum first. Use a brush attachment on both sides to remove dust, which holds odour.
3. Wash with less detergent, not more. Use a gentle cycle and cool or warm water as the label allows. Too much detergent leaves residue that traps smells.
4. Add white vinegar to the rinse, if the fabric allows. Half a cup in the softener compartment helps remove odour. Never mix vinegar with bleach.
5. Dry fast. This is the step that matters most. Hang the curtains in sun or in moving air on a dry day, with a fan if indoors. Feel the seams, hem and heading, which dry last, before rehanging.
6. Rehang and air the room. Leave the window open for a few hours so the room and the curtains settle together.

For a fuller walkthrough by fabric, see our guide on how to wash curtains in Singapore.

If you cannot wash them

Large or heavy curtains, dry-clean-only fabrics and curtains on high windows can be hard to wash at home. In between cleans you can:

• steam the curtains while hanging, then open the window and run a fan
• sprinkle baking soda on a fabric that tolerates it, leave it for an hour and vacuum it off
• open the curtains fully every day so the folds spread out

These help with mild smells. They will not fix a curtain that has started to grow mould.

Aircon, closed windows and smells

Many musty smells come from how the room is used rather than the curtain itself. A bedroom with the aircon on all night and the windows shut all day never gets a change of air. Moisture from people, laundry and cooking has nowhere to go, and fabric soaks it up.

A few habits make a difference:

1. Open the window for at least half an hour after switching off the aircon.
2. Draw the curtains fully open in the morning so the folds dry.
3. Keep the aircon filter clean, since a dirty unit can blow a musty smell into the room that then settles in the fabric.
4. Use a dehumidifier in rooms you keep closed.
5. Keep a gap between the curtain and the glass. A track mounted further from the window, or a pelmet, brings the fabric forward and away from condensation.

When the smell keeps coming back

If curtains smell musty again within a few weeks of washing, look for a moisture source you have not fixed: a leaking window frame, a damp wall, a sill that collects rainwater, or a hem that touches the floor. Curtains that are too long will keep wicking up moisture from mopping. Shortening them so the hem clears the floor by about 1cm often solves it.

Old curtains with a cracked blackout coating, thinning fabric or stains that never wash out may be past saving. At that point replacement is usually the sensible choice.

When to call a professional

Our curtain cleaning service suits curtains that are too large, heavy or delicate to wash at home. We offer on-site steam cleaning, dry cleaning and washing, and can take the curtains down and rehang them afterwards. If the hem is sitting on the floor, our curtain alteration service can shorten them. If the curtains need replacing, our made-to-measure curtains are sized to your drop so the hem clears the floor and sill.

Common questions

Why do my curtains smell musty even though they look clean?

Mildew can grow inside the fabric and in seams before any spots are visible. A musty smell is often the first sign that the curtains are staying damp. Washing and drying them quickly, and airing the room daily, usually clears it.

Why do my curtains smell like wet dog after washing?

They dried too slowly. Damp fabric left for many hours develops a sour smell. Rewash with less detergent and dry them in moving air or sun until the seams and hem are fully dry.

How long does the smell on new curtains last?

A chemical or plastic smell on new curtains usually fades within days to a couple of weeks if the curtains are aired in a ventilated room. Washing first, if the label allows, can speed it up.

Can I use fabric spray to get rid of curtain smells?

Fabric spray can mask a mild smell for a while, but it does not remove damp or mildew. If the smell returns, the curtains need washing and proper drying, or a professional clean.