Bentonite and Montmorillonite clays are particularly effective in helping relieve the itch and pain associated with poison oak. Try this recipe for relief and to stop the rash spreading: mix one teaspoon of salt, a few drops of peppermint oil and a cup of clay with enough clean water to make a smooth paste. Spread this paste on the affected areas and leave in place for 20 to 30 minutes. Gently wash off and re-apply. You can store the leftover paste in an airtight container in the refrigerator for later use.