Perfect for those with sensitive skin, this homemade glycerin soap recipe makes a hard bar of soap that lathers nicely while gently cleansing and moisturizing your skin.
What is glycerin soap?
It sounds like an easy question, but there is really a bit of confusion about what should be called glycerin soap.
When most people think of glycerin soap, they think of translucent soaps. Many think of the translucent melt and pour soaps that can be melted down to make easy, customizable soaps. (Although not all melt and pour soaps are translucent, of course).
What most people don’t know is that there is glycerin in all soap because it is a byproduct of the soap making process.
The difference between translucent “glycerin” soaps and other more opaque soaps with glycerin in them, is that the glycerin soaps have been cooked with certain solvents like sugar, alcohol, and, well, more glycerin, to help make the soap crystals small so that light can pass through. (It’s the soap crystals that reflect light back at our eyes, making soap opaque).
Glycerin soap benefits
Glycerin is a humectant, meaning that it helps retain, or reduce the loss of, moisture.
What’s special about glycerin, though, compared to some other humectants, is that it is an endogenous humectant, meaning we have it naturally in our skin. Glycerin has been shown to help restore moisture and elasticity in the stratum corneum layer of our skin, helping to restore the barrier that protects us.
Interestingly enough, even after you stop using glycerin topically, it can continue to help form a barrier to help prevent moisture loss for up to 2 weeks.
Glycerin soaps are thought to be milder and gentler on the skin. While that probably depends on each particular recipe or soap, I’ve found that this soap has worked well on my son who has sensitive skin with atopic dermatitis. (That said, I still use soaps, or other washing products like gels, sparingly on his skin, and most days only rinse the majority of his skin with water.)
I find this to be a great overall soap for face and body, and I like how it helps reduce acne on my skin.
Watch how I make glycerin soap
The Glycerin Soap Making Process
Making a translucent glycerin soap is really a two part process.
First, you have to make the soap, using a hot process method. (I use my slow cooker which works perfectly for both parts of the process.)
After you have made your soap, you need to dissolve the soap crystals to help allow the light to pass through the soap, making it translucent. To do that, you will use a combination of several different “solvents.”
On my first two attempts, I didn’t spend a lot of time trying to dissolve the crystals. I wasn’t careful to keep the slow cooker well sealed, and I didn’t leave the solvents to work longer, or add more of them, to try to get a more translucent soap.
If getting a more translucent soap is important to you, I’ve given you a range of different solvent values for you to experiment with. I chose to add an amount somewhere in the middle of the given range of each particular solvent. You may want to try adding a smaller amount, and increase, as needed, until your soap gets more translucent. Using a stronger alcohol will also probably help you get a clearer soap.
If you’re really picky about getting translucent soap, I’d suggest reading the book, Making Transparent Soap: The Art Of Crafting, Molding, Scenting & Coloring by Catherine Failor. Her techniques are the ones that most people follow when making both translucent solid soaps and translucent liquid soaps. She has another book about Making Natural Liquid Soaps. If you’re interested in making liquid soaps, I have a couple of liquid soap recipes up on the blog. (You can choose to make a liquid castile soap, or a liquid coconut oil soap, or make both and combine them to get the best of both worlds.)
Choosing oils for a glycerin soap recipe
Because we are going to be using solvents to dissolve some of the soap crystals, it’s best to use oils that make a harder bar of soap. This will help ensure you’ll still end up with a hard, long lasting bar of soap despite the solvent process.
In general, oils that are solid at room temperature tend to make harder bars of soap. (Olive oil can also make a hard bar of soap, but it usually requires a long curing process to get it to harden.) Tallow and coconut oil are great oils for this type of recipe; not only because they make a nice hard bar of soap, but they are also said to be good for making a translucent, rather than cloudy, glycerin soap.
Castor oil is another common oil used in translucent soap making, not because it’s a solid oil that makes a hard bar of soap (because it isn’t, of course), but because castor oil is said to be somewhat of a solvent on its own.
Even after using the solvents, this recipe made very hard bars of soap, and I really love the way it lathers. The coconut oil adds to the cleaning factor of the soap and helps make a bubbly lather. The castor oil helps stabilize that lather. This was the first time I used tallow for making soap because it’s not very easy to find here. (I wanted to make my own, but couldn’t get any butchers to save beef fat for me for rendering tallow.) I have to say that I really love it, and plan on using it more often.
Choosing an alcohol as a solvent
I would have loved to use a consumable alcohol without any added scents or ingredients like Everclear, but I wasn’t able to find anything like that here.
Funny story…
I actually went to the supermarket with my mother-in-law and bought some 70% absinthe because it was the only drinkable alcohol I could find over 50% here in Spain. I was slightly embarrassed buying it, and felt the need to say that it was for making soap. In the end, I felt bad about using an expensive alcohol in my experiments with making a translucent soap, and wasn’t sure how the green coloring would affect the color of my final soap. (I wanted to see what I’d end up with without adding anything at all to it.)
I decided to use some 70% denatured alcohol instead. I was worried about it leaving an unusual scent to my soap, but honestly I don’t notice any off putting fragrances from the alcohol, despite my having forgotten to add any essential oils in the end for fragrance.
I think next time I’d try with a stronger alcohol to see if my soap turns out more translucent. If anybody gives a 96% alcohol, or something similar, a try, I’d love to hear how it goes!
I now have been left with a completely full bottle of absinthe at my house, if anybody wants to come for a party. (Just kidding about the second part.)
Superfatting glycerin soaps
Because excess oils can make for a cloudy soap, I chose not to superfat this soap. (Superfatting is when you add more oils to the soap than what are needed to react with the amount of lye used. Some unreacted oils remain in the soap, and can leave a hydrating film on your skin when you use the soap.)
The excess glycerin in this soap helps compensate and acts as the leftover emollient that helps make a moisturizing soap. I used the same thought process when making my liquid castile soap and liquid coconut oil soap, and find that both are very mild for use on face and body.
Now that I’ve been using this glycerin soap for awhile, I definitely don’t think it’s missing anything, and love it just the way it is. That said, you could always try adding slightly more oil if you prefer to superfat the soap.
Glycerin soap recipe
Homemade Glycerin Soap Recipe (From Scratch)
Makes around 8 bars of soap.
Materials
For the soap
- 304 g distilled water
- 117.7 g lye NaOH
- 440 g tallow
- 200 g castor oil
- 160 g coconut oil
Solvents
- 120 g glycerin Between 98g and 147g
- 300 g 70º alcohol Between 275g and 321g
- 90 g sugar Between 73g and 110g
- 180 g distilled water Between 147g and 244g
Instructions
Make the soap.
- Weigh out the lye in a small, non-metal bowl.
- Weigh out the distilled water in another, larger, non metal bowl.
- In a well ventilated area, carefully pout the lye into the container with the distilled water. You should wear gloves and goggles to protect your eyes and hands. Stir the lye into the water until it is dissolved. The mixture will heat up and get cloudy at first, but will clear up and cool down with time.
- Leave the lye mixture to cool while you weigh out the oils. I find that the easiest way is to place the bowl on a digital scale, tare it, add an oil to the bowl until you reach the right weight. You then tare again before carefully adding the next oil, and between each addition.
- Add the oils to a slow cooker on low heat, and stir them together well. Allow any solid oils like the tallow to melt.
- Carefully add the lye mixture to the melted oils, and gently stir them together. Once the lye solution is fully incorporated into the oils, you can begin to blend them together with an immersion blender.
- Blend with the immersion blender until the mixture thickens to trace. Once the mixture has reached trace, place the lid on the slow cooker and allow the soap mixture to cook for several hours (around 3) until it starts to get transparent.
- You have now made a hot process soap.
Use the solvents to make it translucent.
- Weigh out the alcohol and the glycerin. You will be mixing them together and adding them to your soap. I would have liked to use a high proof alcohol like Everclear, but couldn’t find anything like that here in Spain. I ended up using a 70º denatured alcohol. they say that if you use a higher concentration of alcohol, that it will do a better job of making the soap more transparent. (Perhaps next time I’ll try with a 90+% denatured alcohol. Rubbing alcohol is said to leave an unpleasant scent behind, but I haven’t tried it to verify the difference.)
- Pour the alcohol and glycerin mixture into the soap. You’ll probably end up with chunks of soap floating in the liquid. Try to break them up as best as you can. (I used my immersion blender to break up the chunks and fully incorporate the alcohol and glycerin into the soap. Work in a well-ventilated area for this step and be careful not to have any open flames in the area. (You should always be careful when heating high percentages of alcohol.)
- Cover the crock pot, sealing it as best you can so that the alcohol doesn’t evaporate. (If it evaporates too quickly, it won’t be able to work its magic on the soap.)
If you really have your heart set on making a translucent soap, you should seal your crock pot with some sort of plastic wrap before placing the lid on top. I didn’t have any on hand, and wasn’t really too concerned about making a fully transparent soap, so I just used the regular lid of my crock pot. - Allow the soap to cook, covered and sealed, for around 30 minutes.
- Meanwhile, make your sugar syrup. Weigh out the sugar and water and mix them together in a saucepan over low to medium heat until the sugar has completely dissolved. Remove it from the heat.
- Once the 30 minutes has passed, you can begin to add the sugar solution to the soap. Gently mix it in, trying not to move the soap too much so as not to form a lot of foam or bubbles.
- At this point, you can begin to test the soap for translucence. It will look translucent to the eye, but as it cools, it will become more opaque. The way most people check is by freezing a glass, and adding a small amount of soap to the bottom of the glass to cool it. Keep in mind that you are using a very thin layer of soap, and that when you have a thicker layer it won’t be as translucent.
- To try to get a more translucent soap, you can continue to cook the soap, adding in small amounts of the various solvents and checking the translucence with the frozen glass. (To be honest, I didn’t bother, and just added the sugar, and went right to pouring the soap into the mold. Perhaps next time I’ll try for a more translucent soap, and will give you my tips for what works best.)
- At this point, you can add in any fragrances or colorings. The nice thing about this soap is that because it has been cooking for so long, and has completed the saponification (soap making) phase, you can even use food coloring to color your soaps. You won’t have to worry about the lye reacting with the colorants and changing them as often happens when adding things to cold process soaps.
- Clear the foam off the soap, and carefully pour the soap into your soap molds. Try to be gentle at this stage as any movement can cause foaming of the soap, which will lead to a more opaque soap. (I wasn’t very careful, and my soaps have a more transparent layer on the bottom, with a thin layer that is more opaque at the top, where the bubbly soap settled before hardening.)
- You can skim the foam off and pour it into small soap molds. They will make a more opaque soap that will work just as well as the rest of the soap.
- Allow the soap to set undisturbed overnight.
- The next morning, check the soap for hardness. If it is hard enough, unmold the soap and cut it into bars as needed.
- Allow your soap to cure and dry for several weeks. This is best done by separating the soaps to allow for air flow over them. It’s a good idea to rotate the soaps occasionally so that all sides dry at the same rate. The curing process will allow it to harden and finish any remaining chemical processes to make for a better soap.
My first experience making glycerin soap
The first time I tried to make a glycerin soap, I decided to try using a new wooden soap mold for my newly made soap. I should have experimented with a soap that was easier and quicker to make like my easy, beginner soap.
What happened?
The mold began to leak, and I ended up with my soap solution all over the counter. I scraped up some of it, and tried pouring it into another mold, but by that point I had a lot of parts that were hardening up and floating in the melted soap mixture. I decided that I was going to use my immersion blender to smooth out the mixture before pouring it back into the other mold.
The result?
Because I didn’t let the mixture settle again, I ended up with a more cloudy soap. The soap started to settle on its own leaving a clearer, harder bar of soap on the bottom, and a foamier, opaque soap on top.
What did I learn?
It’s just as important to be careful how you handle the soap when pouring into the molds. You want to be gentle and not incorporate a lot of air into the mixture. That is, unless you are going for this lemon merengue pie look to your soap! (I have to admit that it is kind of cool. The foamy layer is very soft, and almost like a marshmallow.)
Making a loofah soap
I decided to use the translucency of this soap to my advantage, and made loofah soaps. The loofah serves as a gentle, natural exfoliant for bathing.
To make a loofah soap, you can use PVC piping as your soap mold. If you have a PVC pipe cap, you can seal off one end with one of those. If not, you can seal off the end with some heavy plastic and rubber bands.
Add the loofah to the pvc pipe and weigh it down with something. (I used a spoon.)
Once in place, gently pour the soap into the pipe over the loofah.
When the soap has hardened, the easiest way to pull the soap from the mold is to put the pipe into the freezer for at least half an hour. Not only will this help solidify the soap, but it will slightly reduce its size long enough to help you push the soap out of the mold.
Carefully cut the soap into round bars and allow them to cure like you would any other bar of soap.
I’m sure somebody will ask me why the loofah soaps stayed white, while the other soaps turned yellow after during the curing process…
I wish I had an answer. I will say that they were from the same batch, and I didn’t add any colorants or any different ingredients to one versus the other. I poured the bar soaps first, and then filled up the pvc mold for the loofah soaps. If anybody has any ideas about why they aren’t the same color, I’d love to hear them!
ayurvedic soap
Glycerin soaps are milder and gentler on the skin. specially in winter glycerin are are very useful for the skin.thanks for sharing detailed information about the glycerin soap and its benefits.
Sujan De Silva
Hi,
Thank you so much for the recipe.
I tried this using KOH as the lye. because it is said that caustic soda is not much suitable to the skin.
And I experienced a cake forming on the soap.do not know whether this is due to the mismatch of the lye against the oils. can you advice with that?
Thanks.
– sujan De silva
Tracy Ariza
Hi Susan,
You can’t switch out the NaOH for KOH. It will give a totally different result.
NaOH is meant for bar soaps like this one. KOH is meant for liquid soaps.
Neither is good for your skin when used directly. They are very caustic.
When you make soap, though, they are chemically reacted with the oils and neither remains.
Please read my post about working with lye. It will clear up a lot of your concerns and answer a lot of questions for you!
Ka
I made this soap last night and accidentally forgot to add the glycerine! What can I do???
Tracy Ariza
Hi Ka,
I’d imagine you’ll still end up with a nice bar of soap, so you have a couple of options. Cut yourself a bar and see if you like it and keep it as is, or…
This soap should be fairly simple to melt and add when re-melted. You may have to add a bit more alcohol and/or sugar solution to keep things translucent if yours already was and if that’s important to you. If it isn’t (to me it’s not that important), you can just add the glycerin and re-pour into the molds.
If it isn’t melting well without the glycerin, you can add a small amount of water (or one of the other solvents) to help things along. 🙂
Muhammad Yasir
Thanks for the superb recipe. I successfully made the soap but the tallow odor is there in the soap.
I used beef tallow.
Is there any solution to kill the tallow odor.
Regards
Tracy Ariza
Hi Muhammad,
I’m sorry to hear that! I made mine with a deodorized tallow. I wanted to make my own, but I couldn’t get my hands on enough beef fat. (I even asked at several butchers, but nobody wanted to save it for me.)
I ended up finding a shelf stable tallow meant for soap making.
I hadn’t even considered that using a homemade tallow would cause the scent to be part of the soap.
Did you add any fragrance to your soap to mask the scent?
Mine retains a very slight scent of the alcohol used as a solvent, but it’s very light. I’ve had people tell me the soap smells “clean.” (I’m guessing that tallow scented soap doesn’t smell as clean.)
You could try remelting some of the soap and adding a fragrance to mask the scent, but I’m not sure if it will be enough. When you re-melt, you may have to add more solvents to keep the soap translucent if yours was translucent to begin with.
Graciela Peña
Hola, descubrí tu blog ayer y estoy encantada con el mundo de información y la facilidad con que describes los procesos, felicidades y muchas gracias!!!
Tracy Ariza
Hola Graciela,
Muchas gracias-
Tengo que ponerme a traducir de nuevo… lo tengo pendiente. 😉
¿Has visto que tengo blog en español también?
Amy
This soap is incredible and loved your video presentation! I would love to try to make this because glycerine always has been perfect for my skin. Do you know if there is a substitute for tallow? I’m trying to find a vegan-friendly alternative. Your soaps are fabulous! Thank you for any insight you can help me with
Tracy Ariza
Hi Amy,
Thank you so much!
I’ve heard that palm oil works well as a substitute, but I haven’t personally tried it. I have made a vegan version using only coconut oil and castor oil and it makes a very nice soap too. It’s a much whiter bar of soap. Mine didn’t turn out very translucent, but I love it and will be posting it on the blog soon.
Stephanie Pelczar
Love!!!!
Tracy Ariza
Thanks! 🙂
Bluechicken
I was wondering if you was able to melt it and pour? This is so very similar to my recipe for melt and pour but I don’t use alcohol. Instead I use food grade PG. Its my tried and true and I make about once a week. I have bought dentured alcohol. But I haven’t tried it yet mostly because when I make it, it’s to use and I hate to have an unusable batch. Mine is rather soft but I’ve never actually tried curing because of the humidity. I also wanted to help with the question of what to use in place of Tallow. Palm oil is an exact replacement for Tallow. I use them interchangable in all my recipes. (Please no negitive comments regarding my use of palm. I exclusively use humanly sourced palm from essential depo) I prefer to use Tallow.but I don’t always have it on hand.
Tracy Ariza
Hello,
I was to a certain point, but I haven’t really tried to use it like that because I really like the soap so I haven’t really wanted to play with it too much. Let me better explain… I was rebatching some soaps that I didn’t love and first started melting the end pieces of this soap. I also added some of the foamy bits. It melted quite nicely but right afterward I added bits and pieces of the other soaps. I ended up adding a bit of water, but it was mainly for the other soaps. I think this soap helped extremely with the texture of the final soap. I really love the rebatched soap mixture that used this in it.
I have since made this soap using only coconut oil and castor oil- to avoid the tallow- and it’s also quite a nice soap. It is white in color and hasn’t yellowed at all. This soap has since darkened into a more amber color. I’ll be taking pictures in the next week or two because I want to take pictures of the coconut oil soap too and post that recipe. I’d like to update this post with the alternative and with the newer pictures of how this soap has changed.
Thanks for the suggestion about palm oil. I actually bought some when I wanted to try to make a shave soap, and for some reason never did. I was going to try to make some other soap with it, so this might be a nice one to try. It’s really one of my favorite soaps so far!
I’m definitely not planning on giving you any negative comments! I really appreciate your input! I also love that you use humanely sourced palm oil. I don’t really ever use palm oil (or haven’t as of yet) because of the possible issues with it, but I also bought the one I bought because it was said to be humanely sourced as well and I was curious.
If I do give it a try, I’ll let you know.
Humphrey agwuncha
Thanks I see it very interesting and amazing I so much enjoyed the video appreciate
Tracy ariza
Tracy Ariza
You’re welcome, Humphrey!
Humphrey agwuncha
Thanks it is very interesting.