Get started with cold process soap making with tallow in just a few steps!
Did you ever think using a bar of fat can leave you feeling squeaky clean?
Using tallow in soap creates a very hard, long-lasting bar with a gentle lather. It is an ideal ingredient for natural and DIY soaps.
I’d like to welcome Hill from Whet Stone Soapery who going to guide us through the process of cold process soap making with tallow in this guest post.
She makes is simple and straight forward so we can all get the benefits of natural tallow soap in our own homes. You can learn more about Hill on instagram and learn more about her soap and lip balm in her etsy store.
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This post may contain affiliate links. Primal Edge Health LLC may receive a small commission at no extra cost to you for any orders made through these links. All thoughts and opinions are my own and I never promote something I wouldn’t use myself.
The History of Beef Tallow in Soap Making
When I tell people I make soap from grass-fed tallow their first reaction is “what is tallow.” After I explain that tallow is the rendered and stable form of beef fat, their second reaction is “eew” as they imagine themselves rubbing a greasy bar of fat on their skin.
No one knows exactly when soap was first created and by whom, but the earliest record of soap is from the Babylonians around 2800 B.C. Additionally, the Romans, Greeks, Celts and Egyptians each seemed to have developed soap independently of each other. Legend says that in ancient Rome, women were washing clothes in the river at the base of Sappo Hill where animal sacrifices were done. The runoff of animal fats would mix with the clay in the water and the women found that clothes became cleaner in this mixture.
For hundreds of years, this early form of soap was made from fats, oil and wood ash and was used mainly for cleaning wool. Water poured through wood ashes leached lye from the ash, and this lye was boiled in a vat with animal fat. The long process required an experienced soap maker who could test and adjust the mix properly. Too much lye meant the soap was harsh and would damage skin and fabrics. Too little lye and the soap would be greasy and never harden.
Soap for Personal Use
The use of soap for personal hygiene didn’t seem to come around until 18th century France when the chemist Nicolas LeBlanc synthesized a solution of sodium hydroxide. This man-made lye was more reliable and easier to use than wood ash lye leading to soap become a more affordable commodity for the common person.
These days there has been a resurgence of using tallow in soap making, perhaps due to the growing awareness of nose-to-tail use of an animal, or making use of the entire animal to minimize waste. When I originally set out to create tallow soap, I found that my local Utah grass-fed beef rancher was more than happy to supply me with hundreds of pounds of kidney fat. Few people request beef fat from a butcher and the people that do typically use it for cooking, so only a small amount lasts them a long time.
DIY Cold Process Soap Making with Tallow
Getting started with making your own soap is easier than you might imagine. You don’t need to be a chemist. You don’t need industrial safety equipment, only a few tools and a basic understanding of how to safely handle your ingredients.
Before beginning, it is best to have all of your ingredients weighed out ahead of time.
What you need
- Kitchen Scale
- Silicon or plastic spoon or whisk (not wood since the lye can disintegrate it)
- Plastic dish for measuring lye
- Heat resistance bowl for mixing soap (plastic, pyrex, stainless steel or a small bucket)
- Eye protection
- Thermometer (I used a probe or candy thermometer)
- Soap Mold (a silicone mold is easiest although you can use a wood mold or make your own. If you are not using a non-stick material like silicone, you will need to line the mold with parchment paper. For a round bar, I love using a 4 inch PVC pipe, capped at one end and lined with parchment paper.)
- Immersion Blender
- Isopropyl Alcohol in a spray bottle
Know your ingredients
- Lye (100% sodium hydroxide) My favorite brand is Red Crown Lye which I order online, but in a pinch I have used whatever sodium hydroxide I have found at the hardware store. It’s found in the plumbing section since this is also used to clear clogged drains. Just be sure it’s 100% sodium hydroxide.
- Fat and/or Oils We will be focusing on beef tallow although you can use things like lard or bear fat. (I usually render tallow at home but you can also purchase grass-fed beef tallow US Wellness.) Common oils would be things like olive, coconut or castor oil, also called “soft oils” for cosmetic use. Tallow can make a wonderful soap on its own, but bringing a variety of oils into the mixture will provide a better lather which is particularly good if you want to use it for shampoo or shaving. Each oil has its own unique properties when saponified. The coconut oil makes a thicker lather with larger bubbles. Olive oil has minimal lather on its own but adds soothing and moisturizing properties. Castor oil contributes to a stable and fluffy lather and is a humectant which seals moisture into the skin. Typically, castor oil is used only for about 2-5% of the total oils in a soap recipe otherwise the bar can become sticky feeling.
- Liquid Typically this is water, however if you are making, for example, coffee soap, your liquid would be brewed coffee.
- Essential Oils This is optional and I personally love an unscented bar of tallow soap. Some people think it smell a little fatty, but I find that it smells like freshly baked pastries. I never use fragrance oils because of the potentially harmful properties of fragrance and I dislike how artificial it smells. Essential oils are nice, but understand that it’s not going to be a highly fragrant bar of soap that leaves your skin smelling like the scent. In my experience, the essential oils make it more of an aromatherapy soap. You’ll experience the smell more as you are using the soap and less when it is sitting on the counter.
How to Make Cold Pressed Soap + TIPS
There are a few specific and important things to consider while you make your own homemade soaps. Follow the directions and you’ll have nothing to worry about.
Wear gloves, safety glasses and clothing to protect your skin. It is important to note that you should always use protective gear when handling your lye at any point from the crystallized form through to when your soap mixture goes into the molds.
Be prepared to neutralize lye in the event that it comes into contact with your skin.
Phase 1: Lye & Liquid
- Before mixing the liquid and lye, your liquid should be cold. Once you add these ingredients together, the exothermic reaction will cause the mixture to heat up to temperatures up to 200 degrees F. So, if you start off with a warm or hot liquid, it could get way too hot. Use “fridge cold” water.
- When mixing liquid and lye, always add the lye to the water rather than pouring water into the lye, which can cause a small explosion.
- Do this in a well ventilated area as it will give off fumes. Gradually add the lye into the cold water, stirring until it dissolves well.
- You’ll want to cover this mixture with a cloth and let it cool until about 110-120 degrees F which can take one or more hours.
Phase 2: Fats
- Your fat will need to be melted and heated to about 100-110 degrees. When you combine your lye mixture with the fats, it will heat up again and if either ingredient starts off too hot, it can cause an expansion and spilling over of the mixture once poured into the mold or create unwanted textures in the final product.
- I have found that the optimal temperatures are when my lye liquid is 120 degrees and my fats are 110 degrees F, but in general they should be within 10 degrees of each other.
- To time this properly can takes some practice. I will make my lye liquid first, then heat my tallow from solid. Usually, I can time this so the fat is liquid and cooled slightly by the time the lye mixture is cool enough.
- You can also use this cooling time to prepare your other ingredients. Have your mold ready and your essential oils measured as well as any other ingredients you may be adding.
Phase 3: Fat & Lye
- Have your liquid fats in the bowl that you will pour from into the soap mold.
- Slowly pour the lye mixture into the fats, stirring constantly.
- From here, we are looking for the mixture to reach what is called Trace, a pudding-like consistency. You can reach trace simply by stirring and stirring, but depending on the size of your batch, this could take 30 minutes or more. A more efficient way to reach trace is to use an immersion blender. I like to use the blender in short, 3-5 second bursts, then stir with a whisk, checking regularly for trace.
- You want to make sure you don’t over-blend the mixture, as it can seize up and become too solid, making it difficult to pour into the mold.
- You can look for trace by lifting up your whisk and letting the mixture drip onto the surface. If it leaves a mark across the surface, this is trace.
- Once at trace, you can add your essential oils or other coloring ingredients you may or may not be using. If you are adding essential oils, I recommend bringing it to light trace so that it doesn’t seize up when you are stirring in the essential oils. Mix just enough to blend, then it is ready to pour into the mold.
Phase 4: Pouring into the Mold
- Silicone molds are very easy to use and remove soaps from. Otherwise, line your mold with parchment paper and use tape to seal off edges and hold in place, if needed. You’ll need to turn it upside down and tap our firmly.
- Whether using a loaf mold or a tray of individual molds, after pouring in your mixture you will need to tamp out any air bubbles that could be hiding in the soap. Gently tap the mold against the table or shake side to side.
- Spray the surface with alcohol as that will prevent soda ash, or a white film from forming on top. Soda as doesn’t pose a problem other than it isn’t very attractive, but if the soap is for your own use only, you may not care.
- Insulate the mold for about 24 hours to allow the soap to cool more slowly. Use two bath towels; one on top to cover and wrap the second around the sides. After 24 hours, remove the towels. If you are using small molds, you can remove the soaps carefully now. If you have a loaf mold, I recommend waiting another 24 hours to let it harden more before removing.
Phase 5: Cutting & Curing
- If you have used a loaf mold, you will now need to cut your loaf into bars. Don’t wait too long before cutting your loaf as it can begin to harden and may crack or crumble when it’s cut.
- This doesn’t need to be complicated and you can use a large knife to eye the size of each bar and hand-cut. I love the homemade look of an unevenly cut bar of soap, but if your goal is to make them look even and identical, you may want to invest in a simple soap loaf cutter which will assist you in making each bar the same size with a straight cut.
Now, you can celebrate that you have done all the hard work…but your soap isn’t actual soap quite yet.
With cold process soap making, saponification will now happen over a six to eight week curing period. The chemical reaction needs to continue and the bars need to harden and dry out.
- Place your bars on a rack (a baking cooling rack works well) in a cool (not cold), dark area that gets plenty of air flow.
- Stack the bars a few inches apart so they are not touching to allow for air to flow all the way around the soap.
- The smaller or thinner you have cut the soap, the quicker it will cure, but I find that a 1-inch bar is nice to hold onto and lasts a while.
- After six weeks, you can try out your soap. If it leaves your hands feeling slippery or if your skin stings at all, it’s not ready.
Eight weeks may seem like a long time to wait for your homemade soaps, but the satisfaction of creating your own product from beef fat that may have otherwise been thrown away is truly satisfying and worth the wait.
Once you understand the basic process of cold soap making, there are endless varieties of soaps you can make by adding different essential oil combinations, experimenting with fat and oil blends to achieve different lather textures and adding natural botanicals and clays for color. Once you begin to handcraft your own, unique soaps, I guarantee you that you’ll never want to buy another bar of store bought soap ever again.
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Rosemary Lime Tallow Soap Recipe
- Mixing bowls
- Infrared thermometer, optional, recommended
- Immersion blender
- Soap molds (silicon or metal)
- Bath towels
- Knife or soap loaf cutter
- Wire rack
- Gradually add the lye into the cold water, stirring until it dissolves well. Cover with a cloth and let it cool until about 110-120 degrees F, can take 1+ hours.
- Heat the fat and other oils until liquid, then let cool to 100-110F (38-43C).
- Slowly pour the lye mixture into the fats. Alternate between using an immersion blender in short 3-5 second bursts and stirring with a whisk. Check regularly for trace (see more in “TIPS” above). Do not over blend.
- Once trace is achieved, pour mixture into your mold (use a silicone mold or line with parchment paper).
- Tamp out any air bubbles by gently tapping or shaking the mold against the table
- (Optional) Spray the top with alcohol if you want to prevent soda ash (purely for appearance to prevent any white film on the top).
- Insulate the mold(s) with 1-2 bath towels, 1 covering the top and 1 wrapped around. Leave small individual molds for 24 hours, larger loaf pans sit for 48 hours.
- Pop soaps out of silicon molds or turn upside down and tap firmly to release from mental molds.
- Cut 1-inch thick bars with a sharp knife or soap loaf cutter.
- Cure the bars for 6-8 weeks on a rack in a well ventilated cool, dark area. Each bar should be standing alone, not touching the others.
- Test the soap after six weeks. If it leaves your hands feeling slippery or if your skin stings at all, it’s not ready yet.
Do you use tallow soap? What flavors do you like?