The vast majority of hats, from baseball caps to cowboy hats, will benefit from some added waterproof protection. There are several ways to add a waterproofing finish to common materials. For hats in particular, we recommend one of these three approaches:

1. Use a waterproofing spray, plus a seam sealer
2. Use a combo of detergent and alum
3. Use a beeswax or waterproofing bar - (such as Otter Wax)

Waterproof Spray and Seam Sealer

Waterproofing spray and seam sealer are best for leather, nylon and canvas. Of all materials, canvas is probably the easiest to waterproof. For this method you should plan for the weather: pick a day that is not windy or overly humid, if possible. It’s best to do this outside or in a well-ventilated room (especially if you are sensitive to smells or chemicals).

• Step 1 - Clean the hat thoroughly, getting all debris and dust off. Let it dry completely, if you used water to clean it.

• Step 2 - Buy waterproofing spray and seam sealer. These products are easy to find and order online. Amazon and numerous other retail outlets carry both of these items.

• Step 3 - Spray the waterproofing solution onto the material in a steady even layer. Keep the spray bottle about 6-8” from the hat. Make sure to get both inside and outside of the hat. This process is a bit like spray painting, so make sure you’re in a well-ventilated area. And if you’re outside, remember to stay upwind to avoid inhaling any of the spray.

• Step 4 - Dry your hat in a warm, dry place. This step only requires waiting.

• Step 5 - Apply a second coat.

• Step 6 - Squeeze seam sealer on all seams. You can use an implement, like a putty knife, to help ensure that the seam sealer works its way into each of the seams.

• Step 7 - Let dry thoroughly.

Household Products: Detergent and Alum

Detergent and alum are an old-school, reliable method for thoroughly waterproofing nearly any natural or synthetic fabric hat. This is not recommended for leather or suede.

• Step 1 - As with all methods, be sure your hat is clean, and use a vacuum cleaner if necessary to get all the dust out. This step may seem boring but it is super important. A dirty surface will remain dirty forever after waterproofing.

• Step 2 - Mix the detergent solution: 1 lb detergent with 2 gallons water in a bucket large enough to submerge your hat. A laundry sink will also work for this purpose.

• Step 3 - Soak the hat in the solution for recommended time.

• Step 4 - Hang the hat to dry in a warm dry place, preferably outdoors in the sunshine. 

• Step 5 - Mix alum (1/2 lb) into 2 gallons of hot of water and soak the hat for at least 2 hours. Make sure the alum dissolves completely (like Epsom salts). Alum is usually available at grocery stores or drug stores. Also make sure the hat is totally submerged and use a brick or stone to keep it under the solution.

• Step 6 - Hang the hat to dry again, in the sun if possible.

Rub-on Waterproofing Wax Bar

Waterproofing bars are simple to use, require no spraying and no hanging out to dry. They are ideal for canvas hats.

Beeswax is an excellent option, and many people like the Otter Wax brand. This method is similar to using spray and seam sealer but is an all-in-one product and is less toxic.

• Step 1 - Clean your hat!

• Step 2 - Heat both the surface of the hat (hair dryers work best) and the wax itself

• Step 3 - Apply wax with hands and spread it thoroughly into the fabric of the hat.  Make sure you rub the wax into the hat.

• Step 4 - Heat the hat again for 5 minutes

• Step 5 - If needed, smooth the wax into the hat fabric one more time.

• Step 6 - Place your hat in a warm, dry place to “cure.”

Two final things to keep in mind: your hat may become stiff at first, depending on what method you choose. However, it will soften up as you wear it. Secondly, and most importantly, waterproofing methods will usually cause the color of the material to darken a bit. In most cases, the darker color will remain that way for the foreseeable future. It's a small caveat, but it's certainly something to consider before waterproofing your favorite hat!