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.

Equipment:

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)

Thermometer

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.)

Glycerin

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

Step 6:  Once all the Potassium Hydroxide has been added to the glycerin, stir with a whisk to make sure that all pieces have been dissolved.  The solution may be a light amber color at this point but should be clear.

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 7:  Pour the glycerin/KOH solution into your melted and heated oils and mix.   Using the stick blender, continuing mixing as your mixture combines and starts to thicken.  This will happen fast.  Depending on the oils used will determine what stages your will see during this process.  Some recipes will go straight through to the gel or clear amber liquid stage very fast, others will just thicken.  This recipe uses a high percentage of soft oils and therefore does not go to gel right away.  For reference, a 100% olive oil formula using 20 ounces of oils takes about 10 minutes to get to a smooth slightly translucent paste ready for the cook.

Step 8:  As you mix with the stick blender or hand mix, you will eventually see small bubbles floating up from your mixture.  This is more apparent if you use a whisk - so use a whisk in place of the stick blender every so often to test for bubbles.   Now, if your formula is high in olive oil, you may not see these bubbles at all BUT you will see the paste go through the applesauce to thick gel in about 10 minutes or less.  At this point, I set my crock pot to low and let it cook for about 30 - 90 minutes checking every 30 minutes and testing with Phenolphthalein Drops.   One thing to note here - If you stick blend for too long thinking you have not reached trace or the cook stage, you will end up with an opaque layer of foam on top of a clear liquid on the bottom or a thick and somewhat fluffy opaque glob.  This is ok and your soap will still dilute properly.  The higher your hard oils, the more likely this is to happen.  To avoid this, do not over mix your paste with the stick blender.  Let the tiny bubbles fly then leave it to cook.  Remember, the glycerin method is very forgiving. 

This recipe will look like very light caramel color at this point and is not translucent.

Also note that you should not have to cook the paste for hours and hours - using the glycerin method greatly shortens your cooking time which is one of the main reasons people use it.  If you find you are needing to cook for a several hours to get a clear Phenolphthalein test, check your calculations to make sure you do not have a lye excess.

Test your paste with Phenolphthalein Drops every 30 minutes to determine if all your lye has been used up to saponify your oils (no excess lye).  Clear to very pale pink is good.

Step 9:  Once your paste tests clear, turn off the crock pot and let sit overnight.  In the morning  you will have a paste that may or may not be translucent depending on your formula.  This formula creates a caramel colored paste.

Step 10:  Test for excess lye with Phenolphthalein Drops if you have not done so during the initial cook and test for clarity by diluting a small amount of paste into boiling distilled water.  This recipe was diluted at 1 ounce paste to 3 ounces distilled water.  At this point I test the sample soap with my digital pH meter.  This measures out at 9.6 which is an acceptable pH for liquid soap.  pH may naturally lower slightly on its own during sequestration too - don't be too quick to add borax, boric acid or citric acid if you have not formulated with a lye excess. Please note that pH reading accuracy is affected by soap concentration and heat and you can get false readings in too concentrated a soap. Dilute to a 1 - 10% soap solution to get the most accurate readings.

Phenolphthalein drops are a pH indicator to determine if and or how basic your solution/soap is, they cannot accurately tell you the pH of your soap/soap paste only whether you have excess lye remaining in your paste which will affect the overall pH thus rendering a darker shade of pink. They are a good tool to use when making your paste along with a clarity test. Clear soap can still have excess lye in it. The most accurate way to do this is via titration. Some people prefer the zap test (touching cooled soap paste to your tongue and if you get a zap like a 9V battery, you still have excess lye present), others do not.

Step 11:  Dilute your paste as you normally do - slow and with patience.  Many people dilute too quickly and add too much water causing over dilution and very thin soap.  Patience and adding boiled distilled water in very small increments is key.  You will find that soap paste made using the glycerin method will dilute at a much faster rate than with the water method and is often creates a slightly darker soap.  As always, keep your desired concentration of soap in mind when you dilute your paste.  Less dilution water, higher concentration of soap.  Too high a concentration of soap and you may find that you waste a lot of your soap.  Think about the concentrated forms of products you find in the stores that you need must dilute with water before use.  That is what can happen if your soap is not diluted enough and you end up wasting soap.

Completed and diluted soap

~ Faith, Alaiyna B. Bath and Body 

Resources:
BrambleBerry - Base Oils, Fragrance and Essential Oils, Potassium Hydroxide, Lye Calculator and a whole ton of great information on their blog.  You can also start with one of their pre-made soap pastes to get a feel for dilution before jumping into the whole process.
The Lye Guy - Potassium Hydroxide
Columbus Foods/Soaper's Choice - Base Oils
Wholesale Supplies Plus - Packaging
Elements Bath and Body - Fragrance Oils
The Science Company - Phenolphthalein

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