This recipe calls for both washing soda and baking soda:
Powdered Laundry Detergent Recipe #9
12 cups Borax
8 cups Baking Soda
8 cups Washing Soda
8 cups Bar soap (grated)
* Mix all ingredients well and store in a sealed tub.
* Use 1/8 cup of powder per full load.
We have the Borax, washing soda, and Zote soap.
This is the website we are using for recipes: http://tipnut.com/10-homemade-laundry-soap-detergent-recipes/
Oh, gotcha. Sorry for the misunderstanding! I have very hard water, so I guess I wouldn't need baking soda anyway.
My "recipe" is 1/2 bar of fels naptha (or other soap), 1 cup washing soda, 1 cup borax. I grated the soap in the food processor and store it in a quart mason jar. I use a coffee scoop, as it's 1 tablespoon, per load unless it's a huge load and/or really dirty.