Picked up this Patriots Sports Specialties hat earlier today that looks to have never been worn but likely sat folded on a shelf and yellowed over the years:

I wanted to get it clean but A) didn't want the colors on the embroidery to run and B) didn't want to affect the stiffness of the brim. I tested the colorfastness by dabbing a Q-Tip dipped in soapy water on the embroidery. The colors thankfully did not run. I've cleaned hundreds of hats over the years and have learned that dyes, especially red, love to seep into white fabric. Cold water is your friend when dealing with these. I did some additional research and found that dabbing a mixture 1 tsp of white vinegar and 1 cup of cold water will help stabilize the dyes, which is a neat trick I will be incorporating into my cleaning methods.

I then used a mixture of 1 cup cold water, 1 tsp Oxi Clean, and 1 tsp Dawn Platinum to use as a detergent to further clean the hat. I lightly scrubbed the stained parts of the crown (while doing my best to avoid the embroidery) and dabbed away any immediate moisture to avoid dye running and to get the stains out. I then applied a second scrubbing of the detergent mixture and let the hat dry in the sun. Super happy with the final result: