This DIY liquid castile soap recipe is easy and inexpensive to make. It’s a great multipurpose cleaner, perfect for both your body and around the house! Makes 1-2 gallons of liquid soap. (See notes below)
Measure out the olive oil and begin to heat it over low heat. I warmed mine on the low setting of my slow cooker. A slow cooker is perfect for this sort of job because it will gently warm without burning, and keeping things at a steady temperature. (In the picture you can see that I first thought to try using a glass bowl in my slow cooker as a sort of double boiler, but I later found it too difficult and just poured the ingredients directly in the slow cooker itself.
Mix together the glycerine and water, and measure out the potassium hydroxide (KOH).
Carefully add the KOH to the water (and not the other way around!) in a well ventilated area. I usually do this outside. Stir the KOH into the water until it dissolves. It will be cloudy at first, but then it will clear up.
Slowly add in the the KOH mixture to the warm olive oil, and slowly stir them together in the slow cooker over low heat to incorporate the lye mixture into the oils.
Using a hand held blender, begin to blend the ingredients together in the slow cooker. In a few minutes the mixture will begin to thicken and look like mayonnaise, and then just moments later will look like a creamy pudding.
A couple of minutes later, the mixture will begin to look grainy. A lot of people call this the mashed potatoes stage because that's sort of what the mixture resembles. Continue to blend. (If at any point the mixture becomes too thick to blend with the hand held blender, switch to mixing with a wooden spoon, but when working with only olive oil I found the mixture to be pretty workable throughout the process.)
As you continue to blend, it will start to get creamy again, and you will notice that you will start to see translucent streaks in your mixture.
Once you reach this point, you can stop blending with the hand held blender, and begin to stir occasionally with a wooden spoon.
The mixture will begin to thicken up and become more translucent. We are now working on making a soap base paste which will be dissolved into a clear liquid soap. The process will take 3-4 hours, and you will want to check on it and stir it up every half an hour or so.
(See, I told you this takes a bit longer than making bar soap, but the results are worth it!!)
To check for "doneness," we will look to see if our paste is dissolving into a completely clear liquid soap.
To do this, take a small amount of the soap paste and dissolve it in water, and look to see if the water is clear once the soap paste is dissolved. If the liquid is cloudy, you will want to continue to cook the soap in the slow cooker. You can let it cook another half an hour before checking on it again. If it dissolves clear like the soap in my picture, you are finished making the soap paste.
Your liquid castile soap paste is now ready to be stored or dissolved into liquid soap as needed.
This recipe makes 4.5-5 lbs. soap paste which can be diluted to 10-20 lbs. soap or more. That ends up being 1-2 gallons, or more, depending upon desired concentration.
Keep in mind that liquid soap is not as thick as commercial gels and surfactants. Liquid soap is of a thinner consistency, and doesn't need to be thick to be concentrated and work well.
Recipe printed from Oh, The Things We'll Make! Blog. https://thethingswellmake.com/easy-beginner-diy-liquid-castile-soap-recipe/