Using a large cheese grater, grate one bar of soap into a large stock pot.
Add 10 cups of water and heat until the soap flakes are dissolved. You can add 1 tablespoon of liquid glycerin if desired.
Let it cool for an hour or so. This makes just enough to fill up one of the 64-oz soap refill containers.
Use a funnel and pour the mixture into the soap refill container (or a recycled milk jug if you don’t have one). It will take awhile to coagulate, about 24-36 hours.