How to Wash a Baseball Cap

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Structured caps: hand wash only. Machine washing distorts the crown shape and can dissolve cardboard brim inserts. Air dry over a mould — never tumble dry.

Check the Brim First

Before washing any cap, check the brim. Press the brim and try to flex it. If it bends easily and springs back, it is likely a fabric-only brim (modern caps — safe to machine wash with care). If the brim is stiff and holds its curve rigidly, it contains a brim insert. Pinch the edge of the brim — if you can feel layers or hear a crinkle, the insert may be cardboard (used in older caps, common before the mid-1990s). Cardboard inserts dissolve in water, permanently collapsing the brim. Modern structured caps use plastic inserts, which are waterproof, but the machine washing problem is different: the tumbling action of a washing machine distorts the structured crown and brim shape even if the materials can handle water. Hand washing preserves the shape.

Hand Washing (All Cap Types)

Check the care label and brim type

Read the care label first. Check the brim rigidity (see above). If the label says dry clean only, follow it — usually applies to structured wool dress caps.

Spot-treat the sweatband first

The sweatband (inner band) collects the most sweat and bacteria. Apply a small amount of dish soap, enzyme detergent, or white vinegar directly to the sweatband. Use an old toothbrush to scrub gently. Leave for 5 minutes.

Mix a cool water and detergent solution

Fill a clean sink or basin with cool water (never warm — heat shrinks cotton and can distort synthetic structures). Add a small amount of dish soap or a half-teaspoon of mild liquid detergent. Avoid biological detergent on wool caps.

Scrub gently with a soft brush

Use a soft brush (old toothbrush or clean nail brush) to scrub stained areas. The crown, brim edges, and sweatband are the main areas. Brush in small circular motions. Avoid harsh scrubbing on embroidery — it pulls threads.

Rinse thoroughly under cool running water

Hold the cap under cool running water and work soap out of the fabric. Squeeze gently — do not wring or twist. Rinse until no soap residue remains. Soap left in the cap causes stiffness when dry.

Reshape while wet and air dry over a mould

Shape the crown back to its original form while the cap is still damp. Place it over a rounded object to dry — a bowl, a ball, or a purpose-made cap dryer maintains the crown curve. Stuff the crown lightly with clean paper towels if no mould is available. Allow to dry completely in the air, away from direct heat. Never use a tumble dryer or direct sunlight on the brim.

Machine Washing (Unstructured Caps Only)

Only for soft caps with no internal structure and confirmed plastic brim inserts

Only for unstructured caps with confirmed plastic brim inserts

Confirmed: soft cotton twill bucket hats, thin unstructured 5-panel caps, swim caps. Not suitable for: fitted structured caps, New Era 59Fifty types, wool caps, any cap with embroidery over the entire crown.

Place in a mesh laundry bag

A mesh bag reduces direct agitation and friction. It will not fully prevent shape distortion but reduces it. Place the cap alone or with other lightweight items.

Cold gentle cycle with mild detergent

30°C maximum. Delicate or gentle cycle to reduce spin speed. Use a small amount of mild liquid detergent. Avoid hot water and high spin speeds — both distort shape.

Reshape and air dry

Remove immediately after the cycle. Reshape the crown over a mould or stuffed with paper towels. Air dry only — no tumble dryer.

The Dishwasher Method — Does It Work?

The dishwasher method for baseball caps is widely shared online and works in specific circumstances: the cap must have a fully plastic brim (no cardboard), the cap must be cotton or polyester (not wool, not structured foam), and the dishwasher must be run on a cool or economy cycle (not hot). Place the cap on the top rack. Use a small amount of dish soap in the detergent dispenser. The main advantage of dishwashers over machine washing is that the cap stays in a fixed position (not tumbling), which preserves the crown shape better. Disadvantages: the heat element in most dishwashers runs hot enough to distort plastic and shrink cotton — check the temperature. The drying cycle must be disabled. Most modern dishwashers run hot enough (65–70°C) to damage caps, making this method unreliable without checking specific cycle temperatures. Hand washing is more controlled.

By Cap Type

Structured fitted cap (New Era, etc.)

Hand wash only

Plastic brim insert, structured crown with foam or cardboard padding. Machine washing crushes the structured panels. Never tumble dry.

Unstructured dad cap / 5-panel

Hand wash or cold gentle cycle in mesh bag

Soft cotton, no internal structure, usually plastic brim. Most forgiving to wash. Air dry.

Trucker cap (foam front, mesh back)

Hand wash only

The foam front panel collapses and deforms permanently in a washing machine. Spot clean or hand wash, air dry over a mould.

Bucket hat

Machine wash cold or hand wash

Unstructured, soft brim. Usually machine washable on cold gentle cycle in a mesh bag. Check label.

Wool or felt dress cap

Spot clean or dry clean

Wool felts and shrinks when wet. No machine washing. Spot clean with a damp cloth and mild soap. Professional dry cleaning for significant soiling.

Performance / athletic cap (polyester, moisture-wicking)

Hand wash or cold gentle cycle

No fabric softener — coats moisture-wicking fibres. Mild detergent. Air dry. Most synthetic caps handle cool machine washing well.

Vintage / pre-1994 cap

Hand wash very gently

Older caps often have cardboard brim inserts. Flex test the brim (see above) before any washing. If cardboard is detected, spot clean only — never soak.

Removing Sweat Stains from the Sweatband

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Apply a mixture of baking soda and white vinegar (1 tbsp each) directly to the sweatband. Fizzing is normal — it lifts the uric acid salts.

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Alternatively: OxiClean or sodium percarbonate dissolved in cool water, soak the interior for 30 minutes before washing.

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For yellow staining on white sweatbands: hydrogen peroxide (3%) applied with a cotton pad, left 10 minutes, then rinse.

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Never use chlorine bleach on coloured sweatbands — it removes the colour. Oxygen bleach is safe on most colours.

What to Avoid

Tumble dryer

Heat shrinks cotton and distorts the shape of structured caps permanently. Air dry over a mould every time.

Washing machine for structured caps

The tumbling action and spin cycle distort the crown shape. Even caps with waterproof materials are not safe in a machine if they have any internal structure.

Hot water

Hot water shrinks cotton and distorts the cap. Use cool or cold water for hand washing and machine cycles.

Direct sunlight when drying

UV fades colours on the outer cap, and direct heat can distort the brim.

Scrubbing embroidery

Hard scrubbing pulls embroidery threads and distorts stitched logos. Dab gently with a soft cloth.

FAQ

Can you put a baseball cap in the washing machine?

It depends on the cap. Unstructured soft caps with confirmed plastic brim inserts can go in a mesh bag on a cold gentle cycle. Structured fitted caps (like New Era 59Fifty) should not be machine washed — the tumbling action distorts the crown shape and crushes the structured panels. Check the brim: if it is rigid, hand wash only.

Can you put a hat in the dishwasher?

The dishwasher method can work on caps with fully plastic brims and cotton or polyester fabric, but only on a cool cycle. The drying cycle must be disabled. Most modern dishwashers run hot enough (65–70°C) to shrink cotton and distort plastic, so it is unreliable unless you know the cycle temperature. Hand washing is more controlled and predictable.

How do you get sweat stains out of a baseball cap?

Apply baking soda and white vinegar (1 tablespoon each) to the sweatband and scrub with an old toothbrush. Leave 5–10 minutes. Rinse and wash the cap normally. For yellowing: OxiClean or sodium percarbonate dissolved in cool water, soak the sweatband for 30 minutes. Hydrogen peroxide (3%) works on white sweatbands. Avoid chlorine bleach on coloured caps.

How do you dry a baseball cap without losing its shape?

Shape the crown while still damp and place it over a rounded mould — a bowl, a ball, or a purpose-made cap dryer. Stuff the crown lightly with clean paper towels if no mould is available. Air dry completely away from direct heat and sunlight. Never use a tumble dryer — heat shrinks the fabric and distorts the shape.

Got a stain on your cap?

Use the stain picker →