There are a lot of reasons to make your own laundry detergent! From a health perspective, homemade laundry detergent lacks irritating chemicals like perfumes, petroleum distillates, and my personal enemy SLS and SLES. From an environmental standpoint, homemade laundry detergent isn't made with toxic chemicals and byproducts from the industrial process, and it doesn't result in an endless supply of empty plastic detergent containers having to be recycled or thrown away. And from a crafty perspective, it's fun to make, and you can give it any smell you like!
Best of all, from a frugal perspective, Trent at The Simple Dollar calculated that homemade laundry detergent is about 1/20th the cost!
The basic recipe for making your own laundry detergent is: 2 parts soap flakes, 1 part borax, and 1 part washing soda.
Soap Flakes. You can use any soap for this. If you travel a lot, you can save up the free mini bars of hotel soap. The little slivers of leftover soap in the shower work great. A bar of Fels Naptha laundry soap is the classic, of course! You can also buy a cardboard box of soap flakes in the laundry aisle, if you look closely enough. If you want to go super-pure, buy a bar of Dr. Bronner's soap. As a bonus, it smells nice!
Use a cheese grater to turn bar soap into flakes.
Borax. I used to be scared of borax! I think I was confusing it with boric acid. Borax is perfectly safe, and is even used as a food additive in some countries. Borax is a mineral which is mined in the Southwestern United States.
Washing soda, or "soda ash" is sodium carbonate. When you're shopping, look for Arm & Hammer SUPER Washing Soda. Check the label to verify it's sodium carbonate. Apparently many stores (including Walmart) also sell Arm & Hammer Washing Soda (no SUPER), which is sodium bicarbonate or baking soda.
Making The Detergent
Make liquid laundry detergent: the basic process is to melt the soap flakes in simmering water on the stovetop, add the borax and washing soda, pour it into a bucket, and add more water to make five gallons. The Simple Dollar has a great tutorial on this process, including lots of pictures and descriptions.
Make powdered laundry detergent: many people just mix up the soap flakes with the powdered borax and washing soda. Lisa at Condo Blues mixes up one bar of soap, a half cup of Borax, and a half cup of washing soda, and shakes it up in a jar.
Make dishwashing liquid: you can use liquid laundry detergent in a squeeze bottle to wash your dishes. A few drops of citrus oil or a splash of lemon juice will make it smell great!
Scent: Obviously your detergent is going to come out smelling like the soap you used. To customize the smell of liquid detergent, use an unscented soap, and add drops of essential oil.
For powdered detergent the easiest thing to do is find a soap that has the scent you want. I recommend Dr. Bronner's bar soaps, which come in a variety of awesome smells!
Creative Commons-licensed image courtesy of Flickr user Chiot's Run