but the real question is, how do you get them out? I'm assuming these are molds with a design or something, so you can't just line them with parchment paper.
I read in a post about placing the molds in the freezer for a little while--depending on size of mold. I use silicon molds and small plastic candy molds. I first pull the mold away from the sides (for silicon) and then invert and pop the soap out by pressing in the center. To decrease possibility of soda ash, I spritz with 91% isopropyl alcohol after pouring the soap into the molds, and then cover in plastic wrap. Then I place the molds between cutting boards and wrap in a wool blanket and then a quilt around that. I check on them every few hours by working my hand in between layers of the blankets and unwrap when heat is gone. This would be different for milk or sugar-containing ingredients.