The water method is cheap and distilled water is readily available at your local grocery or drug store. Glycerin is more expensive and not as easy to come by plus you need to take into account shipping charges if those are incurred for online or phone ordering from any of the various suppliers of soap making ingredients. Point Water.
The water method can be a very long and drawn out process. From the time it takes to get your soap to trace to the extended cook times plus having to watch and stir every 30 minutes. If anyone has made a 100% olive oil liquid soap from scratch, you know how looooong it takes for that formulation to trace and not separate out. The glycerin method is much quicker in that your soap will come to trace within 15 minutes or so. Just like with the water method, some formulations trace quicker than others. Point Glycerin.
I find that diluting paste created from the glycerin method is much quicker than diluting paste created from the water method. Another time saving feature. Point Glycerin.
The one drawback to the glycerin method that is not found in the water method is the way in which you must dissolve your potassium hydroxide. Your glycerin must be heated to over 200 degrees F in a stainless steel pot in order for your KOH to dissolve. I have had my glycerin reach over 300 degrees as it continues to heat as I add the KOH - a little worrisome for safety. Point Water. ETA: I now add my KOH directly to my glycerin prior to heating and then heat both of them together on very low. No bubbling up of the ingredients as room temperature KOH hits the heated glycerin - much safer.
So, the best method I have found for creating liquid soap is to combine these two methods for a process that is quick, easy, safer and less messy than I find the glycerin method to be. I call it the 50/50 method. 50% of your liquid is distilled water, the other 50% is glycerin. Soap traces fast, does not need a long cook time and no heating of the glycerin to a high temperature. The benefits of the glycerin method without the mess. You can also adjust these ratios to fit your needs as long as you use enough water to dissolve your KOH. My rule of thumb is the minimum amount of water to be 1.1 x KOH. So if I need 4 ounces KOH, the minimum amount of water I would use to dissolve it would be 4.4 ounces distilled water.
I use the following formula for this tutorial.
18 ounces olive oil (I used my calendula infused olive oil)
2 ounces castor oil
4 ounces Potassium Hydroxide (0% superfat and using Summerbee Meadow or Brambleberry calculator)
6 ounces distilled water
6 ounces glycerin
This will result in about 28 - 30 ounces paste
As usual, make sure to have all your safety equipment and gear. 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.
Gather all your soap making equipment (crock pot, stick blender, mixing utensils, phenolphthalein drops, etc.) The assumption here is that you have some experience in liquid soapmaking already.
1. Measure out your oils and heat in a crock pot.
2. Measure out your distilled water in heat proof container, your potassium hydroxide and your glycerin - all in separate and appropriate containers OR you can add your glycerin directly to your oils.
3. Slowly add your potassium hydroxide in small amounts to the distilled water mixing between additions.
4. Continue to mix until your KOH/water solution is clear.
5. If you did not add your glycerin to your oils, you can slowly add it to your KOH/water.
6. Add your water/glycerin/KOH or water/KOH mixture to your heated oils in the crock pot and stick blend.
7. With this formulation you will see it start to thicken within a few minutes and go to a glossy paste (not translucent) within 15 minutes - this is very dependent on the oils you used.
8:20 - start stick blending
8:28 - applesauce stage
8:30 - smooth matte paste (mixing by hand)
8:34 - smooth glossy paste (mixing by hand)
8:20 Start Stick Blending
Quickly Starts to thicken up
8:28 Applesauce Stage
8:30 Smooth Matte Paste
8:34 Smooth Glossy Paste
14 minutes from the time I start stick blending until I have reached a point that I can test my paste and start cooking if necessary. Normally this formula would take 45 minutes to a hour or so to get to this point using all water due to the high olive oil content in the formulation.
I also know that since this formula above is mostly olive oil, I do not expect it to get to the taffy stage as I have never had a high olive oil formula get to that stage.
For comparison purposes, the following is the timeline for my liquid soap that is 65% hard oils (coconut and babassu), 33% soft oils and 2% Cocoa Butter using this 50/50 method:
8:57 start stick blending
9:01 applesauce stage
9:03 thick pudding to mashed potatoes stage
9:05 stiff taffy stage
at this point, a sample (a small amount of soap paste diluted into a small amount of distilled water - see below) tests clear with a quickly measured Ph of 9.6/9.7 (not completely accurate as it is not cooled nor highly diluted, but a good quick indicator for me - 8 minutes.
9. At the 14/15 minutes point I test the paste with the phenolphthalein drops. Test is clear but after a few minutes it gets a medium pink ring around the dollop of paste. This is considered good. No excess KOH and an acceptable pH level when a sample of diluted soap is tested at room temperature.
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.
10. Heat of a few ounces of distilled water and add an ounce of paste. Tests clear. pH reading with my digital ph meter registers at 9.7/9.8. A bit higher than I like but still acceptable for liquid soap. I also find that the pH often continues to stabilize as the soap sequesters - this is mostly due to testing conditions though. If testing in a more concentrated sample or on not at room temperature, your readings will be affected.
Testing paste for clarity - looks good
11. At this point, your paste is considered done and you can turn off your crock pot and let your paste sit for 12 - 24 hours and to finish the process. While fluid while hot, the paste oftentimes will harden up as it cools. Some pastes stay somewhat fluid - each formulation will act a bit different. I prefer to cook it a bit longer to make sure that all parts of the paste are thoroughly cooked through. I will cook for another 2 - 3 hours or so, mixing and testing the paste with the phenolphthalein drops every 30 minutes. Then I will turn off the crock pot and let it cool down for the next 12 - 24 hours. You can cook your soap longer if you would like, you can "cold process it" too - I find that everyone has their own preferences for how long to cook or not cook their soap paste.
After 1 hour cook
After 2 hour cook and sitting in the crock pot to cool (about 12 hours from start to finish).
Beautiful translucent soap paste.
12. Dilute, adjust ph/neutralize if necessary and thicken how you normally would finish your liquid soap. I am going to use my HEC method 2 (thicken while you dilute) to thicken and dilute this paste at the same time since I know what my dilution rate is going to be. It has a current ph of about 9.2 in a concentrated sample which is fine for me so I will not be adjusting it at all. How you dilute, your desired viscosity and your desired soap concentration (the less dilution water the more concentrated your soap, the more dilution water the less concentrated your soap) are all personal preferences. Some people prefer to use as little dilution water as possible to dilute their paste to get a thicker viscosity, but, one must also take into consideration how concentrated the finished soap will be.
Alaiyna B. Bath and Body
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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