1. In a nonreactive pan, such as stainless steel, bring beer to a near boil, then lower heat and let simmer until it reduces to 1/4 cup (about 25 minutes). Remove from heat and let it cool.
  2. Slowly mix the beer reduction into the mild shampoo until fully combined.
  3. Pour the liquid into a clean 14-oz. (or larger) bottle with a tight-fitting lid. It doesn’t smell like beer, so you can wash hair as usual.

Beer Shampoo Recipe photography by Lori Foy.