This is the recipe I used: Vegan Homemade Laundry Detergent. She provides a wonderful explanation (even doing the math; calculating 10 cents per load!). I doubled the recipe, and keep mine in an old yogurt tub (along with an old measuring spoon).
I have used this recipe in hot and cold washes, and it has worked perfectly. I add one Tablespoon of detergent to the water, and it seems to dissolve almost instantly. Then I add the clothes.
Many people have concerns regarding using Borax, especially on clothing. This recipe was the most frugal concoction I could find during our time of unemployment. At that time, I made no claim to its supposed safety; I just needed to get our laundry clean! Since then, we have chosen to use more “safe” natural cleaning methods, as our budget has allowed. Lindsay has a great recipe here for a natural detergent recipe, along with some other safe options.