How to get sweat stains out of hats

How to remove sweat from a hat

1. 1

   Check what the hat is made of

   Look for a tag, and check the tag or the maker's information for whether the visor has a cardboard insert. Note whether it's cotton, polyester, wool or felt, and whether it has leather or suede trim.

   Why: Hats are exempt from the federal care-label rule, so many have no instructions. Cardboard brims, wool and leather all rule out soaking.

2. 2

   Brush off loose dirt

   Brush the hat with a soft brush, or go over it with a vacuum's brush attachment.

   Why: Dry soil turns to mud when it's wet and can spread into the sweat stain.

3. 3

   Fold the band out and apply cleaner

   Turn the sweatband forward so you can reach it. Mix a little mild liquid detergent into cool water, or apply an enzyme pretreatment to the stained band on cotton or polyester caps, and leave it a few minutes.

   Why: Sweat is mostly a protein residue with body oils. Detergent lifts the oil, and enzymes break the protein into pieces that rinse away.

4. 4

   Scrub gently with a soft toothbrush

   Work along the band with a soft toothbrush in small strokes. Keep the brim and crown as dry as you can.

   Why: Gentle brushing loosens residue from the band's weave without soaking the stiffened parts of the cap.

5. 5

   Rinse with a damp cloth

   Wipe the band with a cloth dampened in cool water, rinsing the cloth often, until no more suds come out. Blot with a dry towel.

   Why: Leftover detergent attracts soil and can leave a ring of its own.

6. 6

   Air-dry on a round form

   Set the hat over a bowl, a rolled towel or a cap form in a shaded, airy spot. No dryer and no hair dryer. Check the band once it's dry and repeat if a line remains.

   Why: Drying on a form keeps the crown's shape, and heat warps visors, shrinks cotton, mats wool and sets any sweat that's left.

Why hat bands turn yellow, and why you can't just wash them

A hat's sweatband sits against your forehead all day, collecting sweat, skin oil and hair products. Sweat itself is mostly water, salts and a little protein; once the water evaporates, salt lines and a yellow or dark ring build up layer by layer. Like other protein stains, it sets with heat, which is why hot water and the dryer make it worse.

The bigger problem with hats is structure. Baseball caps have stiffened front panels and a molded visor that may contain cardboard; soaking can warp the visor and collapse the crown. One cap maker's care guide says structured caps should be spot-cleaned only, never machine-washed or submerged. That's the main difference from sweat stains on clothes, where a soak and a hot wash are the usual fix.

Cotton, polyester, wool and felt

Cotton and polyester caps tolerate cool water, mild detergent and enzyme pretreatment on the band. Wool and wool-blend caps need cool water only, with no enzyme cleaners and no bleach: wool is a protein fiber that enzymes can digest, and chlorine bleach damages it. Wool felt hats such as fedoras and cowboy hats felt and shrink with heat, moisture and agitation, so keep water to an absolute minimum and take heavy sweat stains to a hat cleaner.

By situation

Set-in yellow stains on a cotton cap

Apply an enzyme pretreatment to the band and let it work longer before scrubbing, then rinse and dry. The cap maker's guide also suggests a paste of baking soda and water on cotton caps. Old, heavy build-up may take several rounds and may not fully clear.

White or light-colored caps

Oxygen bleach, mixed as the package directs and applied to the band only, can help with yellowing on white cotton or polyester. Test on the inside of the band first. Avoid chlorine bleach: it can strip color from panels and logos and weakens spandex in stretch-fit bands.

Unstructured or washable caps

If the cap is soft, has no cardboard and the label says it can be washed, you can hand-wash it in cool water with mild detergent. Still air-dry it on a form, never in a dryer.

Wool felt, straw and leather-trimmed hats

Brush felt dry and keep it away from water and heat. Straw and leather or suede trims shouldn't get wet. For valuable hats, or heavy stains on any of these, use a professional hat cleaner.

What not to do

• Don't put a hat in the dryer. Heat warps visors, shrinks cotton, mats wool, melts logo adhesive and sets sweat stains.
• Don't soak or machine-wash a structured cap. Water softens cardboard brim inserts and can collapse the crown's shape.
• Don't use hot water on the sweatband. Heat coagulates the protein in sweat and sets the stain.
• Don't wring or bend the visor. It can crease or crack the brim insert permanently.

Other methods that work

Baking soda paste

A paste of baking soda and a little water brushed onto a cotton cap's band, left for a while, then wiped off. Iowa State Extension also lists a baking soda paste for underarm sweat stains.

Caution: Wipe it off thoroughly so no white residue is left.

White vinegar for color changes

If old sweat has changed the color of the band, the American Cleaning Institute suggests dabbing white vinegar on old stains, then rinsing.

Caution: Test on the inside first, and never use it with chlorine bleach.

Dishwasher or washing machine

Washing caps in a dishwasher or washer is a popular trick, but cap makers advise against it for structured caps, and the heat and water pressure can warp the visor. There's no authoritative support for it.

Caution: If you try it anyway, only on an unstructured, washable cap, with no heat-dry.

Stain still there?

A ring formed around the cleaned area

Water or detergent wicked outward and dried. Dampen the whole band evenly with a clean cloth, blot, and dry it on a form.

The visor went soft or wavy

The insert got wet. Reshape it by hand while damp and let it dry flat or on a form, away from heat. A cardboard insert may not fully recover.

The colors on the front panel bled

Clean one color panel at a time with a barely damp cloth, and rinse quickly. Bleeding that has dried in usually can't be reversed.

Safety

• Never mix vinegar or ammonia with chlorine bleach.
• Test any cleaner on the inside of the band before treating the visible part.

Never mix cleaning products; see chemicals you must never combine.

Questions

Sweat on other surfaces

• Sweat stains: the complete guide
• Sweat on clothes
• Sweat on a mattress
• Sweat on sheets
• Sweat on white clothes

Other stains on a hat

• How to clean a hat