Here is how I turn my handmade olive oil castile bars into thick liquid soap. I love how it feels and use it for household cleaning, bathing, shampoo, laundry, bathing pets...and so on. For the price of a 4 ounce bar soap, you should be able to make around 24 ounces of liquid soap. Now, that is making a dollar (and your soap) stretch a long, long way.
Items you will need are: a large pot with a lid, distilled water (adding water to anything is introducing an opportunity for germs, so use distilled water or a purified water...never use plain tap water), a bar of soap, a whisk for stirring, a grater, and scales. Be sure all of your tools are clean and dry when you start.
In the photographs, you can see I am making a large batch of liquid soap. I am using a 4 quart sauce pan with lid, 40 ounces of water, and 8 ounces of bar soap. The ratio you want to keep in mind for your recipe is 1 part solid bar soap to 5 parts water. That means for every one ounce of solid bar soap, you will need 5 ounces of water to dissolve it.
First, you will need to grate the bar of soap. The cheese grater in your kitchen will work beautifully. The finer the soap flake, the easier they will dissolve in the water. Once the soap is grated, place the soap flakes in a bowl and set aside.
Next, measure the distilled water into the pot and bring it to a boil. Remove the pot from the burner and turn off the heat.
Add the soap flakes. Spoon them into the water (please be very careful not to splash hot water on yourself) and give them a good stir. Cover the pot with the lid and let it cool to room temperature. Stir it every now and then to make sure it is coming together properly.
The next set of pictures will show you the stages the soap goes through while dissolving.
Soap flakes added to hot water. Stir well, cover, and let sit.
This is the four hour mark. Still a little bit too chunky, so I have added more hot water and some heat to help with melting. Don't worry, the measurements I gave at the beginning include the extra water added here.
Next morning...now this is what I was hoping to see. Nice, smooth, thick, semi-transluscent soap. The white on the top is foam from stirring so much. The foam is just soap, but if it bothers you, you can skim it off.
This soap has a pretty amber honey color. It is thick, but still easy to use. It has a nice pour and a low creamy lather. The scent is minty with a hint of lemon and roses (I used a bar of my Peppermint Castile and a piece of a Lemon Rose French Pink Clay Castile). It is time to bottle this soap for use. Be sure the vessel is clean and dry. Store your soap out of direct sunlight and away from heat. Under the sink or in a linen closet is perfect.
Just in case something goes awry, here's how to fix it. Say the soap is too thick and gloopy. Start by stirring in another ounce or two of HOT distilled water. Use the whisk to incorporate the water into the soap, stirring gently until it looks the way you want it. Allow the soap to cool after each addition before adding more water. You could also preheat the stove to 175*, turn it off, and place the covered soap pot inside the oven. Sometimes a little external heat helps loosen the soap enough to dissolve.
Oops again. What happens when you've added too much water and the soap is now thin. Simply leave the lid off the pan and let the excess water evaporate. This usually only takes a day or two...and it could take up to several days depending on how thin the soap is and how thick you want it to be. Remember, this is not rocket science, it is just soap. It is very easy to adjust and to correct mistakes. Even if you mess it up, it still works as laundry soap.