Here are three recipes for homemade laundry detergent that we talked about last night. 

Tara's recipe:
http://frugallygreen.blogspot.com/2008/05/how-to-make-your-own-laundry-soap.html
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Diana Bean's recipe:
2 cups borax
2 cups super washing soda
2 bars fels naptha soap

If you want to use a different soap (such as ivory), you'd probably need to use 3 bars. Fels Naptha is larger bar and is supposed to be the best for laundry. Mix together in the food processor.
Use 1 or 2 Tbsp a load.
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Diana Burks' recipe:
1 4 lb 12 oz box Borax
1 4 lb box Arm & Hammer Baking Soda
1 box Arm & Hammer Super Washing Soda 55 oz
3 bars of Fels-Naptha soap (grated)
2 small containers of Oxy Clean (optional)

This made a large Tupperware full (I'm guessing 10" by 16" and maybe 6" deep. Use 1-3 Tablespoons. I use 2 especially with my husband's work clothes an have been happy with the outcome!