I snagged this from Rey at The Peasant and the Pea. So, it's been tried out by someone I personally know and trust. She got the recipe originally from Tip Nut, I believe. Anyways, all the materials cost about $8 (give or take depending on where you shop and what you buy.)
Homemade Liquid Laundry Detergent
2 quarts of water
4 cups grated bar soap
4 cups Borax
4 cups Washing Soda *washing NOT baking*
4 gallons of water
A clean 5 gallon bucket with a lid.
That does not say four bars of grated soap. It says four cups of grated bar soap. There is a fundamental difference. It only took me two and a half bars of Ivory to get my four cups of grated soap. I grated it with a very fine cheese grater.
My first question to Rey was: What the hell is washing soda and where the hell do you find it? Wal-mart apparently, and possibly the drug store, or you might have to check online. Wal-mart had it where I live in Central Texas, but they only had Arm & Hammer. I would've rather had an off label, but such is life. Borax is also something that you don't always encounter, but at least I knew what that was from my Gramma. I was also able to find it at Wal-mart. You usually find both of these ingredients near the Oxy-Clean or other laundry boosters.
I still have a good portion of each box left, though I am not sure if I have quite enough for a full second batch. I would say you can get at least one and a half batches out of each box, thus reducing the actual total cost of each batch.
Heat your 2 quarts of water to a simmer, and slowly --- very slowly --- add in your grated soap. I was using a rubber spatula to stir, and I used the rubber spatula to scoop up some soap and stir it in. Once all the first scoop of soap was dissolved, then I got another scoop. Rey discovered the hard way that if you dump all the soap in at once it melts into a lump, and you have to stir forever to melt it down. I think the total scoop/stir/melt process only took about 20 minutes. If that.
Dump your hot soapy water into your bucket, and add the Borax and Soda. Stir until it is as dissolved as it is going to get. The 4 gallons of water I added in 2 quart batches. The water needs to be hot-ish in order to dissolve everything, so I used my sauce pot and heated it up on the stove while I stirred what was already in the bucket. Not to boiling, just hotter than tap water. Stir, stir, stir. Everything will eventually get mostly dissolved. Clap the lid on it and put it by your washer. Use 1/4 c per load. Stir before each time you use it, because even though we stirred it well, solids will settle.
I got a stick from the yard for a stirrer after the water got too deep for my spatula, that way I wouldn't have to dedicate a kitchen utensil to the laundry.
Five gallons of laundry soap for less than $8. It lasted Rey (who has a family of four) for several months. She crunched the numbers over on her blog, and the results were about half as much as buying Sun laundry detergent, which is one of the cheapest ones. You can make it smell prettier by adding essential oils or soap scents (purchasable from most hobby and craft shops) if you like.
You can use the same recipe, only without the water, for a powdered detergent, but I like liquid for rinsing cleaner.