Well, I made it last night but it hasn't been 24 hours yet. It did make a sort of watery gel which is what the recipe says. The hardest thing I did was to wait until the solution thickened on the stove. But once it did, you could certainly tell it was done. I am waiting until 10 tonight to see what happens since that will be the 24 hours. It did go from a yellowish type of liquid to a white today. I have kept my laundry detergent bottles to put this in tomorrow. As far as the Fels Naptha soap, you can buy it online or use Kirk's castile soap but I honestly don't think it makes a difference what soap you use. I am going to try it out tomorrow and see what happens. I'm excited!