Simple and natural cold-process soap recipe. Uses four eco-friendly oils, easy-to-understand soap-making instructions, and a DIY video.
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Today it’s back to basics with a simple cold-process soap recipe. The bars you make with it are gentle on the skin, palm oil free, and eco-friendly. I even share how to reuse a drinks carton as a mold. The finished bars are a creamy white, and the lather is light and fluffy. Everything about this recipe ensures that the end product is good for you and the planet.
I know that many people are hesitant to make homemade soap, so I’ve made the recipe as easy to follow as possible. It includes only four soap-making oils, water, and sodium hydroxide. No fragrance, no additives, nothing extra. Simples. Soap making can be expensive, so the fewer ingredients you use, the more money you’ll save. It makes the soap-making process easier too. This cold process soap recipe is also the main recipe in the Lovely Greens Guide to Natural Soapmaking. It’s a 68-page guide that teaches you how to make natural handmade soap and includes recipes toward the end.
Eco-friendly Cold Process Soap Recipe
One ingredient that you’ll come across a lot in cold process soap recipes is palm oil. It’s linked to deforestation, climate change, and obesity (as a major ingredient in junk food). I avoid it altogether in this recipe, though I’d argue that using sustainable palm oil is not a bad thing. It’s also a Vegan recipe since there are no animal products included. If you’d like for the recipe to be even kinder to the planet and your health, use organic oils. Buying and using them supports sustainable agriculture and healthier ecosystems.
Another way I’ve tried to make this recipe low-impact is by using a recycled mold. Not a purpose-made soap mold but an old drinks carton that would have probably been discarded. Though Tetrapak is technically recyclable, it’s debatable whether it’s worth the effort. Reusing them this way gives them a second life.
Great for Naturally Coloring Soap
There’s another reason that I’m sharing this recipe. The bars of soap it creates are nearly pure white and absolutely perfect for coloring with natural ingredients. Many soap recipes include oils and butters that are naturally a deep yellow or even greenish-yellow in color. This color of the oils survives the soap-making process, so any additional color you add could blend with it. For example, if you added blue woad powder to this yellow oil soap recipe, you could get green soap! However, with the soap recipe below, you’ll get white soap bars, meaning soap colorants will come through true and bright.
If having pure white bars is important for you, make sure to use pomace olive oil instead of extra virgin olive oil in the recipe. The latter is not only more expensive but is far darker in color. Plus, I think pomace olive oil is more eco-friendly than EVOO in soap making. It’s extracted using a technique that squeezes every last drop out of the olive pulp, ensuring nothing goes to waste. Though it’s lower grade for food, it’s perfect for soap making. There’s nothing worse than waste.
What is Trace
There are only ten real steps in the recipe below. I don’t count the prepping step or the last item that explains shelf-life. That means only ten steps to make eco-friendly cold-process soap from scratch. The most difficult step to understand is what ‘trace’ looks like and when to put down your stick blender. Trace results from oil and water forming an emulsion and kickstarting the saponification process. The photo above should help you see what the soap should look like at that stage.
Adding Scent to a Bar of Soap
This recipe is unscented, and the scent is clean and like pure soap. If you want to add essential oils for additional scent, I recommend using this chart to figure out how much to use. Typically, for a small batch like this, you’ll use about three teaspoons of essential oil to scent it. Essential oil is typically added at trace, but you can also stir it in at the same time as adding the lye solution. You can also use fragrance oils to scent soap, but please be aware that they are synthetic and not particularly eco-friendly.
Cold Process Soap Making Instructions
Making handmade soap is both art and science. There are a few ways to make soap, including hot process soap making, but cold process soap making is my favorite. It involves mixing fats such as tallow, lard, mango butter, cocoa butter, and avocado oil with a lye water mixture. You can use almost any fat, both vegetable, and animal, to make handmade soap. It’s all down to personal preferences and either choosing a good recipe or learning how to formulate your own.
The chemical reaction that results transforms the ingredients into a new natural compound that we know as soap. In a good soap recipe (always put new ones you find through a lye calculator), there is no lye left in the soap at the end. It transforms into the soap itself! I’ve tried to make each as easy to understand as possible but if you’re still unsure, have a read through the Natural Soap Making for Beginners Series:
- Natural Soap Ingredients
- Soap Making Equipment & Safety
- Beginner Soap Recipes
- The Soap Making Process
Eco-friendly Cold Process Soap Recipe
- Stainless steel pan for melting the solid oils
- A large bowl for measuring the liquid oils into
- Empty milk or juice carton
- Rubber gloves
- Prepare your workstation with your tools and equipment. Put on rubber gloves, eye protection, and an apron. Carefully pre-measure the ingredients. The solid oils into the pot, the liquid oils into a jug, the water into another heat-proof jug, and the lye in another container.
- Prepare the recycled soap mold. Rinse out an empty drinks carton and let it dry upside down. When fully dry, cut out the side that the pouring spout is on. A cutting blade is better for this than scissors. Use the cut-out paper to block the open end of the carton. I fold it over the bottom of the carton and then fit it inside the top of the carton. This helps to create a flatter surface on that side of the mold rather than a pointed shape from what was the top of the carton.
- Next, dissolve the lye (Sodium hydroxide) crystals in water. In an airy place, outdoors is best, pour the lye crystals into the water and stir well. There will be a lot of heat and steam, so be careful. Try not to breathe it in. Leave outside in a safe place or in a shallow basin of water to cool.
- Melt the solid oils in a stainless steel pan on very low heat. When melted, remove from the heat and set on a potholder. Pour in the liquid oils. If you have the olive and castor oils in the same container, stir them together first before pouring them into the pan. Castor oil is pretty sticky, and it's easier to pour when mixed with lighter oil.
- Measure the temperatures of the lye solution and the oils. You should aim to cool them both to about 95-100°F / 35-38°C. Use an infrared thermometer or digital kitchen thermometer*.
- Pour the lye solution into the pan of oils. I recommend pouring the liquid through a sieve to catch any potential undissolved lye. You can also pour the lye solution against the side of the stick blender if you'd like to reduce the chance of air bubbles forming in your soap bars.
- Dip the stick blender into the pan and with it turned off, stir the mixture. Next, bring it to the center of the pan, and with both your hands, hold it on the bottom of the pan and blitz it for just a couple of seconds. Turn it off and stir the soap batter, using the blender as a spoon. Repeat until the mixture thickens up to 'Trace.' This is when the batter leaves a distinguishable trail on the surface. The consistency will be like thin custard.
- Working quickly, pour the soap into the mold. Give it a tap to settle it.
- For a truly pure white soap through and through, place the soap in the refrigerator and leave it there overnight. You can also leave the soap sitting on the counter during this time. If the house is warm, there's a small chance of the center gelling, and your bars having slightly darker centers, though.
- The next day, take the soap out of the fridge and set it somewhere to rest for another day. Once 48 hours have passed, you can take the soap out of the mold and cut it into bars using a kitchen knife. You can get six to eight decent-sized bars of soap from this batch.
- Cure it for 28 days. Curing means leaving the bars spaced out on a protected surface out of direct sunlight and in an airy place. This allows the extra water content to evaporate out fully. Here are full instructions on how to cure soap.
- Once made, your soap will have a shelf-life of up to two years. Check the oil bottles that you're using, though. The closest best-by date is the best-by date of your soap. If your handmade soap is destined as gifts, here are some pretty and eco-friendly soap packaging ideas.