Hot Process Glycerin Liquid Soap

Step 1 – Melt the Butters and Oils and Make the Lye Solution Combine the coconut oil, sunflower oil, castor oil, and the olive oil in the slow cooker. Turn the oil on high, cover and allow the oils to melt, about 15 minutes, depending on how hot your cooker is.
Bring the lye mixture to a simmer on low/medium heat. DO NOT WALK AWAY WHILE HEATING THE LYE SOLUTION. The glycerin will foam and may even crackle a little. Do not be alarmed! Keep stirring the lye solution constantly until the lye dissolves, 5-8 minutes. If you see any remaining undissolved chips of lye, turn the heat back on and stir some more.
Step 2 – Bring the Soap to Trace and Cook the Soap
Pour the hot lye solution into the oils. The oils temperature should be around 160° F.
Stick blend on high until all of the oil has been emulsified, about one minute until it reaches a milky thin trace, it may take longer though. Don’t worry about over stick blending. The batter will be at a thin trace, the consistency of thin gravy.
Cover and cook the soap on high for about 20 minutes. Stir the soap with a spatula. You will notice it start to thicken up a bit. Cook the soap another 20-40 more minutes, stirring every 15 minutes, or so. The soap is done when it forms a clear, amber-colored liquid covered in a layer of foam. When you remove a bit of the soap on a spoon, it will harden into a soft, transparent paste.
The easiest way to check for doneness is to take you can use phenolphthalein drops or make a 1% solution of soap paste in distilled water and check the pH with a pH meter. The pH will be at or below pH 10. One final way to check for doneness of the soap is to take a tiny bit of the soap and dissolve it in hot distilled water. It should form a transparent product. If it is cloudy, cook the soap a little longer.
Step 3 – Dissolve the Soap Paste
Bring 2 quarts (64 oz.) of distilled water just to a boil in a large stock pot. VERY SLOWLY, about a cup or so at a time, pour boiled water into the slow cooker to within a half inch of the top. (If you pour too quickly, you will have a soapy volcano on your hands!) The soap will seize up into large blobs of soap paste. Don’t even bother stirring it at this point - it’s too sticky!
Cover the cooker with plastic wrap and cover with the lid and reduce the heat to low. The plastic wrap is optional, but prevents evaporation, so you don’t need to keep adding distilled water. Allow the soap to cook undisturbed for 2-3 hours.
Peel back the plastic wrap and stir the soap with a spatula. Scrape the bottom of the cooker and break up some of the lumps.
Replace the plastic wrap and replace the lid. Cook on low one more hour and stir once again. At this point, it’s easiest to just cover the soap, turn off the crock pot and leave it overnight. The next day, stir it thoroughly. If there are any remaining lumps of soap paste, add a little more water and turn the cooker on low again and cook another 30-60 minutes.
Place a 5 Liter pitcher or a stock pot on your scale and zero it. Carefully transfer your soap to the pitcher or stock pot with a ladle or measuring cup.
Add distilled water to bring the total weight of the soap to 112 oz. (4.96 kg). Stir with a spatula to combine.
Step 4 – Fragrance the Soap
If soap is too thin you may want to make a saline solution for thickening it. While the soap is diluting make a 20% saline solution. Combine 14.11 oz. (400 mL) of distilled water and 3.5 oz. (100g) of table salt in a microwaveable bowl or measuring cup. Microwave on high for about 2 minutes, stirring after 1 minute or until dissolved. Set aside.
It’s easiest to fragrance and scent only a liter at a time of your liquid soap until you know how it will behave. You don’t want to risk your entire batch! Weigh 980g (34.6 oz.) of soap in a 4 qt. measuring cup or pitcher and add 20g (0.71 oz.) (2%) of your favorite essential oil or fragrance oil to the soap. Stir well with the spatula.