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Make sure you are working in a well-ventilated area and wearing your protective clothing (apron, gloves, and glasses). When you’re ready, prepare the lye solution by weighing the water and potassium hydroxide into separate containers. Carefully add the potassium hydroxide to the water and stir until dissolved, so that you are not inhaling any fumes you may want to turn your head away from it as you stir. As this is an alkali that can cause serious burns. Place the lye in a safe and secure place where it won’t be knocked over until its fully dissolved and clear.
Once the oils have fully melted give them a good stir to make sure they are well combined. Keeping the slow cooker on low add the lye solution. There is no need to wait for it to cool as you do when making solid cold processed soap.
As always I prefer to start mixing manually with a spatula for the first few minutes before changing to an electric hand blender. Always be cautious and remember to give the blender a quick blast before using it just to release any trapped air bubbles.
Using the electric blender bring the mixture up to a light trace. Once you have reached a light trace you will need to bring it up to a nice thick one, so that it looks a bit like mash potato. This may take a while depending on the speed/power of the blender and the oils you have used so be prepared for it to take anywhere between 10 to 30 minutes. As you don’t want to fry your blender try blending in 1 or 2 minute blasts.
When you have reached the mashed potato stage it’s time to let the cooker do its bit, so pop the lid on and let the mixture cook. This could take around 4 to 7 hours depending on how hot your slow cooker gets when it’s set on the lowest heat setting. If you have a warm setting this may be a better option.
As your soap batter cooks it will need stirring every 20 to 30 mins. You may notice the it go through various stages whilst it’s cooking, the final result should be a glossy golden translucent color similar in texture and look to Vaseline but not in color. This is what we call the soap paste stage.If you are not sure if it is fully cooked and ready for diluting there is a quick test you can do. Take a teaspoon full of the soap paste and mix it with 25g of distilled water, as the soap dissolves the water should just be fairly clear or just a little cloudy. If it’s very cloudy give it another 30mins cooking and test again. It’s worth mentioning that the water in your test will only go clear when using distilled water, any other type of water can result in remaining cloudy. At this point, you can move to Part 2 (dilution) right away or you can leave the paste to sit in the crockpot overnight and deal with it the next day. Just make sure the crockpot is turned off and the lid is on.
Diluting The Soap Paste
You can now choose to dilute some of the paste and store the rest for a second batch later. Just make sure that any paste you are saving is stored in an airtight container for later. The paste will last for up to one year if kept in the fridge and can be diluted when you need it in exactly the same way.Deciding how much water to add to your paste to thin it down can be a little tricky as many different oils and butters require more liquid than others. Although you can thicken the soap if it is too thin, it’s much easier to get it right the first time.I usually work on a ratio of 1 to 2, so if I have 700g of paste I will dilute it with 1400g of water. You can do this by placing a container on the weighing scales and setting them on zero before adding the soap paste. Once you have the correct weight (700g) place it back into the slow cooker and weigh out double the amount of hot distilled water (1400g).
2 liters Distilled Water
Once you’ve added the water to the paste, give it a good stir, it will at this point feel a bit like you are pushing it around the pot rather than stirring it. Then put the lid on the slow cooker and turn it onto the lowest setting for around an hour. You can leave it on for longer but you will need to keep an eye on it and give a stir now and then. The soap could take a good 24 hours to dissolve so you do need a bit of patience here. Never be tempted to leave the cooker on overnight, the soap will continue to dissolve in the water even without the heat, it just takes a bit longer.
Don’t worry if skin begins to form on the top of the soap, this is just undiluted soap and it can be moved to one side so that the diluted mixture bellow can be poured into a fresh container. You can then add a little hot distilled water to the skin and leave it to dissolve. Once the soap has dissolved it should be the color of the liquid oils you have used. If it’s too thick, add more distilled water until you are happy with its consistency.
Now it’s time to PH test your soap. If you have cooked it long enough and measured the ingredients accurately it should be between 6 to 9 (green) when you dip a PH strip into it. This is a good level and is now ready for color and fragrance. If it’s not then you will need to lower the PH value. To neutralize the soap and give it a lower PH value, mix 14g of citric acid with 56g of boiled distilled water. Adding this should bring the PH level down, but it can make your soap cloudy and also give a temporary curdling effect. Give it a good stir then leave it alone to settle for a while.
Adding a preservative is always controversial, as the soap has a high PH you don’t need to add a preservative however if you are likely to be keeping it in the bathroom or selling the soap, I would recommend adding one. This will also extend the self-life from 6 to 18 months.
You can add fragrance or essential oil at 2%. Many fragrances and essential oils can cause a reaction when you add them, making them cloudy or/and most commonly making the soap thicker or thinner. It may be an idea to remove a small amount of the soap for a trial run. For colors I find liquid soap color is the best to use as mica seems to fade over time. Add a drop at a time until you reach the desired color.
Essential Oil or Fragrance Oil, Liquid Soap Dye
It is a good idea to keep a cup of distilled water (room temp is fine) to add to the soap if it becomes too thick. If it becomes too thin, which is common when using citrus essential oils, it can be thickened with salt that’s been dissolved in hot distilled water. I work with 20% salt and 80% water, adding it a bit at a time until I’m happy with the consistency.
Shelf Life: Without a preservative, your liquid soap will last around 6 months. using one will extend the self-life to 18 months.The recipe shows almost 2 days to make this soap, but remember that most of the time is not really active, it is spent waiting for the processes to complete.Stage 1: Making The Soap Paste
The soap paste in this recipe will take around 6 hours to cook depending on the heat setting on your crockpot.
Stage 2: Dilution Stage
The dilution time usually takes around 24 hours, you don't need to do anything to it during in this stage, however, it's almost impossible not to give it a quick stir now and again.