I've used this recipe for about 6 months now and it's been great. Clothes come out clean and smelling fresh. And it's so cheap--it calculates to less than $.01 a load! You also know that it's free from the chemicals and toxins that are store-brand detergents, even the supposed "free and clear" kinds.
Homemade Laundry Soap
1/3 bar Fels Naptha or other type of pure soap, such as Ivory.
½ cup washing soda
½ cup borax powder
~You will also need a small bucket, about 2 gallon size~
Grate the soap and put it in a sauce pan. Add 6 cups water and heat it until the soap melts. Add the washing soda and the borax and stir until it is dissolved. Remove from heat. Pour 4 cups hot water into the bucket. Now add your soap mixture and stir. Now add 1 gallon plus 6 cups of water and stir. Let the soap sit for about 24 hours and it will gel. You use ½ cup per load.
I found the original recipe with detailed directions, pictures and tips at the bottom. I used an Ivory Soap bar and my hand blender to mix it all up after it had gelled. I mix it and keep it in 5 gallon paint bucket with a lid.
Let me know if you have any other questions or if you give it a try!