Moldy Clothes and a Musty Closet: Saving the Wardrobe and Fixing the Closet

By John Calhoun, owner of Mold Remediation Gettysburg PA · Updated October 26, 2026

“I just found this on my good coat.” That’s usually how it goes: a winter jacket pulled out in November with gray spots on the shoulders, or a pair of dress shoes from the back of the closet that came out fuzzy. The clothes can usually be saved. Brush off what you can outside, wash in the hottest water the label allows, use bleach only if the label says it’s safe, and let things air-dry until the stain is gone. The closet is the harder part, because whatever made the coat grow mold is still in there.

Saving the clothes

University extension services have been fighting mildew on fabric for generations, and their advice lines up:

1. Take it outside and brush off loose growth, so you’re not spreading it around the house.
2. Wash in the hottest water that’s safe for the fabric, with regular detergent, per Oklahoma State University Extension. Some items need more than one wash.
3. Don’t machine-dry until the stain is gone. Oklahoma State notes that heat can set stains. Air-dry, in sunlight if you can; University of Georgia Extension notes sunlight helps slow mold.
4. Bleach only where the label allows it. Missouri Extension says never to use chlorine bleach on silk, wool or spandex.
5. Send dry-clean-only items to a cleaner, and tell them what the spots are.
6. Know when to stop. Oklahoma State is honest that mildew can permanently damage most fabrics. If a smell or stain survives a couple of washes, the garment may be done.

Leather gets its own treatment. Missouri Extension suggests a wipe with equal parts denatured or rubbing alcohol and water, then drying it in a current of air.

Reading the bleach triangle

The Federal Trade Commission’s Care Labeling Rule requires labels to warn you when bleach isn’t safe: “no bleach,” or “only non-chlorine bleach, when needed.” Many labels use symbols instead. University of Tennessee Extension’s care symbol guide decodes the triangle:

Ten seconds with the tag saves a ruined sweater.

Why the closet grows mold in the first place

A closet on an outside wall is a cold box. Building Science Corporation points out that such a closet will be colder than the bedroom it’s attached to, and that if a closet has mold in it, its relative humidity has gone above about 80%. Clothes packed tight against the wall block whatever warm air might reach it. The surprising part: Building Science also notes that adding a supply air vent to a closet makes the problem worse by cooling the surfaces further.

For fabric, the Smithsonian’s conservation scientists say stagnant air above 80% relative humidity will support mold on cotton and linen, and wool and silk above about 92%. Closed, cold and still is exactly the condition a closet creates.

Two other things feed it. Missouri Extension notes that molds feed on starch and that soiled clothes mildew more easily, so a starched shirt or a jacket hung up damp from the rain is an invitation.

Fixing the closet

• Keep clothes and boxes off the outside wall. NDSU Extension recommends leaving space there and leaving closet doors open in very cold weather.
• Let air in. Building Science says louvered doors help.
• Nothing goes in damp or dirty. Let clothes air out before hanging them. Kentucky Extension advises against storing clothing in plastic bags.
• Check the whole-house humidity. The EPA recommends keeping indoor humidity below 60%, ideally between 30 and 50%. A cheap hygrometer in the closet tells you more than guessing.
• A small, careful heat source. Missouri Extension describes leaving a 60 to 100 watt light bulb on in a small closet to dry it, kept well away from clothes because of fire risk.

If the wall itself is spotted, that’s condensation or a leak behind it. Mold in the corners every winter explains the condensation side, and a musty smell with no visible mold can mean the problem is inside the wall.

Old closets and empty houses

In the borough, the Census Bureau estimates nearly half the homes were built before 1940, and an older house often has less insulation in its outside walls than a new one, which makes a closet on that wall colder still. The same estimates count about 3.6% of borough homes as held for seasonal use, and a closed-up house is where wardrobes go musty unnoticed. If you have a house that sits empty part of the year, leave closet doors open and keep the humidity in check. The Gettysburg housing data page has the numbers.

The hand test

Put your hand flat on the closet’s back wall, then on an inside wall of the same room. If the back wall feels noticeably colder, that’s your answer to why the coat grew mold. Move things off it.

This is John Calhoun at Mold Remediation Gettysburg PA. If a closet keeps going musty no matter what you wash, I’ll measure the wall and find out whether it’s condensation or water getting in. The mold remediation in Gettysburg, PA page explains how I work, and the list of mold services shows the rest.