Four years ago I posted a question here about salting out soap, which was received with some confusion. I now have reached the point where I have mastered salting out to my own satisfaction. I will describe my procedure, not because I think it original or in any way better than any other, but because I could find no such procedure anywhere, and my experiences might help another person who finds himself with a similar problem. Caveat: I make functional bath soap, NOT suitable for milady's boudoir. It is plain lye soap, yellow to tan in color, made from whatever oil or grease I can come up with. Nonetheless, my objective it to make it (nearly) colorless and odorless, a real challenge when starting with such "crude" oil. When I make soap from relatively clean oil, I shoot for 5% superfat -- so there is no excess lye in the soap. However, when I plan from the start to purify the soap by salting out, I use excess lye -- which will be washed away in the salting-out step. My latest batch of soap was a real success, not because the result was exceptional, but because the starting oil (used cooking oil saved, apparently, to make biodiesel!) was about the color of motor oil, and smelled rather bad. I cleaned this oil as much as possible by straining through cloth, boiling it up with water and letting it separate, but the resulting water contained little in the way of impurities, so further refining the oil was not going to help. Therefore, I saponified the entire lot (~13 lbs) using a slight excess of lye, and following the usual sort of procedure. I cook my soap hot -- 150F or so -- which I can get away with because I use no additives in it. As a result, the soap forms in minutes and requires little or no curing. I did my first salting out right away merely by adding two or three liters extra water, and, when that was mixed in, an excess of salt. After boiling this up -- mainly to mix it -- I let it cool outside a couple days (till I could get back to it). When cool, I dug through the hardened soap and found that the brine was nearly black, and had gelled like aspic -- something I'd never seen before when soap making. After washing away this ugly gel, I added about 3L of water to the pot and heated it up, breaking up the mass of soap by slicing it, mashing it, and running it through a 1/4" hardware-cloth strainer. (This mechanical work was needed because the soap had hardened as it cooled. I learned from this, and in the future will transfer the soap off the brine before the soap fully cools and sets up.) When the hot soft soap was homogeneous, I added about 1 kg of salt to saturate the water, and continued heating and stirring until the soap floated atop the brine. I then transferred the soap to another container, leaving the nearly black brine behind, and repeated the salting out by the same procedure. (See bottom.) The final brine was only dark amber, and I judged that clean enough for me, especially since the odor was gone. I ladled the soap into rectangular plastic containers to a depth of about 2.5", covered them and let it set up overnight. In the morning, I sliced it into bars, which I set on toweling to dry further. This procedure yielded over 50 bars of soap, roughly 1" x 2.5" x 3.5" -- a convenient size for the bath. My question of four years ago pertained to the soap not sticking together when salted out. This problem has never occurred to me again. I find the hot, salted-out soap behaves very nicely. But perhaps a better description of my salting out process is warranted. The following is based upon my understanding and observations: Soap mixes infinitely with water, but not with brine. Therefore, my procedure is to add a moderate amount of water to the soap mix (3L worked well for this batch that started with 13 lbs oil), and heat and mix till the water and the soap are homogeneous -- soft soap. To remove the excess water, I use enough salt to saturate the water present -- roughly 350 g salt per liter of water. (No, that's not exactly correct, but it doesn't matter. This isn't rocket science.) Since I use rock salt, it takes a little while to dissolve, but as it does, the creamy soft soap starts to separate into a somewhat denser hot soap, while the brine tends to settle to the bottom. When the salt is mostly dissolved, I let the mass settle out. At this point, there will be some brine still mixed with the soap, but that doesn't matter. As I learned, the time to judge the purity is before the mass cools completely and the soap hardens. Pull some brine from the bottom. I judge the brine by color. If it's dark, you might want to repeat the salting out. To do this, ladle the soap into another container, throw out the brine, and repeat the salting out by first adding water to the soap, then adding salt to the soft soap. Repeat until you're satisfied -- it only cost you a little water, salt, fuel, and time.