I use a 19 Century recipe which has Tallow, Olive Oil, and Lard in it. I add 1/2 cup finely grated soap per each recipe batch I make.
Here is the recipe
Homemade Liquid Laundry Soap Recipe
This simple laundry soap recipe will leave your clothes clean and fresh and only comes to about 3 cents per load!
1/3 bar Fels Naptha Soap $.97 per bar at Walmart, so $.33/recipe( Ivory and Zote will also work)
½ cup washing soda - $2.77/55oz box at Walmart (13.75 ½ c. per box), so $.20/recipe
½ cup borax powder - $2.99/76oz box at Walmart (19 ½ c. per box) (20 Mule Team), so $16/recipe
½ c grated homemade bar soap (scented or unscented)
2 gallons water
Grate the soap and put it in a sauce pan. Add 1/2 gallon of water and heat it until the soap melts. Make sure all the pieces melt! Only stir occasionally. Too much stirring will cause too many bubbles. Let soap melt slowly on it's own.
Add the washing soda (NOT baking soda) and the borax. Stir until all is
dissolved. Remove from heat. Pour into a 2 gallon bucket. Use warm tap water and add the remaining 1 1/2 gallons of water to the melted soap. You can add about 10 drops of fragrance of your choice or leave it the scent it is.
Cover and let sit for 24 hours.
It will look like and have a consistency of a big bowl of jello once it has totally cooled. This is normal. Break up the mass with a big wooden or plastic spoon. You can store in the bucket it was in, or use empty milk jugs, or Hawaiian Punch containers, or Walmart's 1 gallon fruit punch. They have a nice handle on them and are easy to use and carry.
Use 1/2 to 1 cup of liquid laundry soap per load. No more or your clothes will have a grayish tinge to it because of the build up of the soap!
Homemade powdered laundry soap recipe
If you prefer powdered laundry soap, then follow this recipe.
2/3 bar Fels Naptha - grated
1/2 cup Borax
1/2 cup Washing Soda
½ cup homemade bar of soap (scented or unscented) - grated
Put all the ingredients in a food processor and whirl until well blended.
Store in air tight container. Use 1-2 tablespoons per load.
Both recipes are low-sudsing so they work especially well in high efficiency washing machines.