I decided I wanted to try a simple, large batch of powder-type detergent. So I went for the basic 3 part recipe, but in the easiest quantities: 1 large box of borax, 1 large box of washing soda (which is different from baking soda in that is is sodium carbonate NOT sodium bicarbonate...interesting.)
and a bar of laundry-type soap.
I did this outside, I grated a bar of soap and combined all three ingredients in a garbage bag. It was powdery. It looked suspect. Very "Breaking Bad". I filled an old container I had sitting around and labeled it "Laundry Soap". About half my batch fit in this container, I have the rest in the garbage bag waiting to refill the container.
Here's the kicker. You only use 1 TB of soap per load. This batch of detergent could last me months and months!
I used it to wash a regular load of clothes and it was great. I used it to wash a sheet and mattress protector that had been in an accident, a pee accident. There was no pee smell lingering after I washed with the detergent. So, thumbs up so far! I will say the smell of the soap bar is a little weird to me. The clothes don't smell like it, but when I open the container to use the detergent, it's not my favorite smell. Next time I would use a bar of Zote (another laundry soap) and see if I like that better.
You can get Borax at Target, and I got the Fels-Naptha at CVS, but the Washing Soda was hard to find. They had it at Berkeley Bowl West. All the ingredients together cost me about $8.