2 cups Bar Soap (Fels-Naptha, Ivory, Sunlight bar soap, Kirk’s Hardwater Castile, or Zote -- nothing heavily perfumed)
1 cup Washing Soda
1 cup Borax
Grate bar soap to a fine powder (a food processor works best). Mix all ingredients well and store in an airtight plastic container. Use 2 tablespoons per full load (if you have hard water, you may need more).
All ingredients can usually be found on the laundry aisle.