Glycerin Method Liquid Soap Making Tutorial

Glycerin Method Liquid Soap Making.

The most common method for making liquid soap involves adding Potassium Hydroxide to distilled water to make your lye solution.  Glycerin can be substituted for the water in liquid soapmaking. Glycerin speeds up the saponification process so that you achieve the various stages of creating your paste much faster and cuts down on the hours upon hours of cooking time.  I also find that diluting the paste made using the glycerin method is also a much quicker process and often require less dilution water.  The glycerin method is also very forgiving and almost foolproof as long as your recipe is run through a lye calculator so that you have the correct amount of Potassium Hydroxide (KOH) for your oils.  Brambleberry's and Summerbee Meadow's Lye Calculators using a 0% - 3%  superfat (make sure to set it to Liquid Soap) have never failed me either.

As with any soapmaking method, there are a few basic rules but beyond that, everyone has there own techniques and methods to achieve their final product.  Here I will show you my method for creating liquid soap using glycerin in place of water.

You will need the following

9/4/13 - ETA:  I have had several people ask for the formula I used for this tutorial.  Since this is a formula that I carry in my line of soap products I cannot give the exact formulation.  However, I can tell you that this tutorial uses 20 ounces of oils (14% hard oils, 86% soft oils)  calculated Potassium Hydroxide and glycerin amounts.  As usual, always run your formulation through an appropriate lye calculator.

Crock Pot - I use a 4.5 quart crock pot with 3 settings - Warm, Low and High
Strong Solid Stirring Utensil
Stick Blender
Stainless Steel Saucepan/Pot for Making the Glycerin/KOH solution
Container for measuring Potassium Hydroxide (KOH)
Digital pH Meter to test pH of soap
Phenolphthalein Drops to test for excess lye and paste doneness

Ingredients for Paste:
Base Oils (Coconut, Olive, Babassu, Almond, Castor, etc.)
Potassium Hydroxide KOH

Ingredients for Dilution and finishing:
Distilled Water
Glycerin (Optional)
Citric Acid (Optional)
Fragrance or Essential Oil (Optional)
Thickening agent (I use HEC) optional

Please use all safety precautions including wearing eye and hand protection, long sleeves, long pants and closed toed shoes.  Both Sodium Hydroxide and Potassium Hydroxide are caustic materials which will burn if they come into contact with your skin or eyes and can do some serious damage.  Not something to scare you away, but always take appropriate safety measures when making soap from scratch.

My 4.5 quart crock pot does a great job on formulations with 20 - 30 ounces of oils.  Any more than that, and the mixture gets too close to the top of the pot.

Step 1:  Calculate your water and potassium hydroxide amounts.  I use Brambleberry's Lye Calculator for liquid soap with a 0 - 3% superfat.  If find their calculator works well for my formulations and I do not superfat above 3%  as excess fats that cannot be saponified may cloud your soap.  I also do not formulate with a lye excess which would require an added step of neutralizing the excess lye afterwards.

Step 2:  Measure out your oils into the crock pot and melt them on high.  Bring oils to a temperature of about 160 degrees F. 

Step 3:  Measure out your glycerin into the stainless steel pan.  You will want this pan to be large enough to handle the bubbling up that will occur when you add your KOH.  You do not want this to overflow your pot.  Since I usually make small batches at a time, I use a 2 quart Stainless Steel saucepan.  This size works great for about 12 ounces glycerin.  Larger batches will require a larger pot.  Make sure that it is stainless steel only.  The Potassium Hydroxide will react with other metals or coatings.

Step 4:  Measure out your Potassium Hydroxide into a suitable container.

Step 5:  Heat your glycerin until it reaches at least 200 degrees F.  You must heat the glycerin or the KOH will not dissolve.

ETA: You can also add your KOH to your room temperature glycerin and heat them together on very low heat.  Doing so will prevent the danger associated with adding room temperature KOH to very hot glycerin as that is what causes it to puff up as seen in the video.  Continually mix this with a stainless steel whisk or spoon until KOH is dissolved.  Once the glycerin reaches 300 degrees F, I turn off the heat source and just let the KOH finish dissolving.

Step 6:  Once the glycerin has heated (my glycerin is usually 250 - 300 degrees F), you will SLOWLY add your KOH - small amounts at a time.  Each time you add the KOH it will bubble up, then settle down.  If you add too much at a time, it will bubble over.  If your solution starts rising too high, remove from the heat and allow it to settle down mixing with a whisk.

Vegetable Glycerin Heating Up

Adding Small Amounts of Potassium Hydroxide

 The bubbling up of the solution after a small amount of 
Potassium Hydroxide is added

Video Showing How Small Amounts of 
Potassium Hydroxide React with the Heated Glycerin

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