How to Clean a Sweaty Baseball Cap

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I want to clean up my baseball cap without ruining the fabric or construction of the cap (the bill). 
Sweaty in Sweetwater

Hey there,

I wasn’t expecting the level of research that it would take to answer this question. There are so many variables when it comes to baseball cap construction. Not only do you have to take into account the fabrics used to cover the bill and to make up the cap itself, but you also have to think about the band and potentially the badge or how the badge is held in place. On top of all of that comes the brim itself. If the brim is cardboard, you can generally forget any method of cleaning that involves soaking, submerging, or otherwise saturating the hat.

If the hat is constructed with wool, you also have to worry about shrinkage. Under no circumstances use hot water and take the drying step very seriously, or you’ll have a hat fit for your little nephew.

So before we go into removing sweat stains, let’s talk about a quick ounce of prevention for the future. I tease my husband about the number of hats he has, but. . . it’s worth having a couple of caps for different purposes. Have one for lawn mowing or the gym and another for running errands or whenever you might want to look a bit nicer. I know to some of you, it might sound silly to have a good baseball cap, but some people love their hats or, more to the point, the way they look in them, and that is all that matters.

If the cap has sweat stains and a cardboard brim, you will need to stick to spot cleaning. First, test to see if the material is colorfast. If you are using a spot treatment like Shout, for example, first put a little on a white rag and rub that on the most inconspicuous (inside) part of the hat you can. If the color comes off, it’s not colorfast, you are just out of luck. Congratulations, you have a gym or lawn mowing hat. If you have serious sweat stains, you can TRY the soaking method, leaving the bill hanging out, but know that your brim may not make it. You can use the paste and brush method to remove the stains on the brim, but, it’s going to be a touchy business. Reshape it carefully and cross your fingers, but do know that there’s a very good chance that this hat may not make it. Proceed with caution and low expectations.

black ball cap on white counter with pineapple in background

If your hat has a plastic brim and minor sweat stains

You can submerge the hat to clean it, but you will want to give it a head start on the soaking process by applying stain remover to the worst of the sweat stains (after testing the colorfastness). Give the stain remover some time to work, then dunk it in a bucket of water (about a gallon, with a 1/4 cup of liquid laundry detergent). Before dunking the hat, make sure that your detergent doesn’t contain any bleaching agents.

Let the hat soak for a few hours.

Then rinse the hat thoroughly in the sink.

Take a towel and ball part of it up to approximately your head shape. Place it inside the hat and set your contraption in front of a fan to dry. If you are drying a wool hat, make sure the head-shaped part of your towel is firm so the hatband doesn’t shrink. Wait until the cap is dry before removing the towel.

Serious sweat stains with a plastic brim.

First, do your colorfastness test. Next, make a paste of baking soda and water, and gently scrub that in with an old toothbrush. Rinse. Follow that up with a dilute solution of vinegar and another gentle scrub with your toothbrush and a good rinse.

Once again, spot treat any remaining stains.

Follow up with a soak in 1/4 cup bleach-free detergent and 1 gallon of water. Then follow the drying steps outlined above.

What about the dishwasher?

Skip it.

Dishwasher manufacturers don’t recommend it and — let’s face it — you can replace a hat much more cost-effectively than you can your dishwasher.


Wear cheap hats when you know you are going to get sweaty.
If your hat has a cardboard brim, it might not make it through the process.
If the hat isn’t colorfast, it’s not worth the effort; downgrade it.

Good luck!

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