Simple & Moisturizing Hot Process Soap Recipe
Make soap from scratch using this simple and moisturizing hot process soap recipe. The recipe includes skin-loving mango butter and yogurt and includes a DIY video along with full hot-process soapmaking instructions
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This is a straightforward hot process soap recipe that will give you between eight and ten good-sized bars. It includes just four relatively common soap making oils, including coconut oil, olive oil, castor oil, and lush mango butter. You’ll also melt half of the mango butter and add it after trace as a superfatting oil. This step makes all the difference in how the soap feels when you use it—a creamy yet well-lathering bar of soap perfect for hands, body, and even face.
One of the best things about hot process soap is that by the end of the cook, saponification is complete. What that means is that although it still needs to be cured, you don’t have to worry about lye still being in hot process soap batter. Technically, it could be used right away but it will lather better and be gentler if cured. More on that below.
Cold Process vs. Hot Process Soap Making
The vast majority of the soap recipes that I share include instructions using the cold-process method. I’ve even recently released a comprehensive Guide to Natural Soapmaking that focuses on making soap from scratch in that way. In many ways, hot-process can be very similar to cold process in that you combine oils and a lye solution and help them saponify – in other words, to become soap.
The main difference between cold-process and hot has to do with temperature. You cook hot process soap to speed up the full process of saponification so that, in the end, the lye and oils have completely transformed into soap. Typically, you use a slow cooker (a crockpot) for cooking hot-process soap, but you can also do it in the oven or on the stove-top.
Curing Hot Process Soap
In standard cold-process soapmaking, saponification is mainly complete in the first 48 hours, but it can take up to a month to finish. The exception is handmade dish soap, which you can technically use after two days. However, if you use cold-process body soap before the cure time is up, then it can feel harsh on your skin, or not have the bubbles and lather that it could have if you wait for the minimum 28-cure time to complete.
Hot process soap is different since doesn’t have any lye left in it after the cook. That’s why a lot of people assume that it’s then finished hardening in the mold that it can be used right away. It’s a little more complicated than that though, since curing does three things. It allows the soap to completely saponify (cold process only), it allows excess water to evaporate, and it allows the crystalline structure inside the soap to fully form. The last two are very important for hot process soap and without a cure time, your soap will not perform well. Learn more about how to cure soap.
Simple Hot Process Soap Recipe
I’ve created this simple hot process soap recipe for beginners, including experienced cold-process soap makers. Many people who have been making cold-process for years feel a bit daunted by the idea of cooking soap in a slow cooker. The instructions and explanations I provide will make the transition more comfortable and help to answer your questions.
One of my biggest questions when I was first researching how to make hot-process was which recipes to use. It isn’t immediately obvious, but you can make practically any from-scratch soap recipe in either the cold-process or hot-process method. The benefit of the cold process is more control over colors and final texture while making soap with the hot process method is quicker. You also don’t have to deal with issues like soda ash forming on your bars in hot-process.
Temperatures in hot process soap making
In cold-process soap making, you keep a close eye on the temperature of both the lye solution and the base oils. You mix them together typically between 100-130°F (38-54°C) and then bring the mixture to trace. You finish by adding extras and pouring the soap batter into the mold. The soap can even heat up on its own afterward, and if you use enough water and insulate it, cold-process soap can reach up to 180°F (82°C). At least for a short time before it gradually begins cooling.
Most hot process soapmakers aren’t as meticulous about temperature, at least, not until the end of the cooking process when they want to add fragrance and other additives. Slow cookers vary, but the typical model cooks at 165°F (74°C) on low and around 200°F (93°C) on high. This range is ideal for pushing soap through saponification when the heat is steady and prolonged. Cooking a batch of hot process soap usually takes between 30-60 minutes.
Hot Process Soap Making is HOT
When you make a lye solution, it can reach up to 200°F (93°C), as can oil melted on high in a slow cooker. If you bring them together to trace at this temperature, then strange and unfortunate things can happen, including odd soap textures and even volcanos out of the slow cooker. The constant heat from the slow cooker at a high temperature can also contribute if the soap batter is already very hot.
That’s one of the ways that I’ve structured this recipe in a way that mimics a cold-process soap recipe at first. Keeping temperatures lower at first can help ensure success for the beginner. I feel that it also makes the process more comfortable for the cold-process soap maker.
Water Amount in Hot Process Soap Making
When you cook soap in hot-process soapmaking, there will be water evaporation—a small and undiscernible stream of steam from the air vent in your slow cooker’s lid. If there’s too much water lost, then the soap at the cook’s end will be challenging to work with. That’s why hot-process soap recipes need to use full-water amounts. Standard recipes call for the water amount to be 38% of the amount of base oils used by weight. You can also create a lye solution with a 25% lye concentration – a ratio of 1:3 by weight, lye to water. For example, 100 g lye would be mixed with 300 g distilled water.
Many soapmakers prefer to work with a specific lye concentration vs. the more traditional method of calculating water based on the recipe’s oils. Either work, though.
I’m using the traditional method in this recipe but have calculated for part of the water amount to be yogurt. Hot process soapmakers often add a bit of yogurt after the soap has cooked and cooled and swear by its ability to make the soap both creamy in texture and more fluid. If it has active cultures, it could help the bars harden quicker, though this is debatable. If you’d like this recipe to be vegan, you can replace the yogurt with the same weight of distilled water, or perhaps with a vegan dairy alternative.
Moisturizing Hot Process Soap Recipe
It’s time to get cooking! Now before we jump into this simple hot process soap recipe, let’s talk about ingredients. The coconut oil you use should be refined, but the more expensive virgin coconut oil will do if you can’t find it. Castor oil is a thick and sticky oil that is common enough in beauty care and helps create stable lather in handmade soap. There are several types of olive oil, including extra virgin, pomace, and mixed types. All will work, but the final bars may vary in color.
Mango butter is our luxury superfatting oil in this recipe, and it is incredible for soap and skincare. Combined with the other oils, it gives this soap recipe its creamy yet bubbly and cleansing lather. The moisturizing aspect of soap made from scratch comes from its natural vegetable glycerin content — it makes a world a difference!
One of the biggest questions I get is whether you can substitute oils in soap recipes. If you’re wondering that too, please read how to change and customize soap recipes. Lastly, if you’d like to see how to make hot-process liquid soap, I have a recipe for that too. It’s more advanced, though, so I recommend you make this moisturizing hot process soap first.
Simple and Moisturizing Hot Process Soap Recipe
Equipment
- Stainless steel pan for melting the solid oils
- Rubber gloves
Ingredients
Lye solution
- 3.94 oz Sodium hydroxide 112 g (also called lye)
- 10.19 oz Distilled water 289 g
Solid oils
- 7.05 oz Coconut oil (refined) 200 g (25%)
- 1.41 oz Mango butter 40 g (5%)
Liquid oils
- 16.93 oz Olive oil 480 g (60%)
- 1.41 oz Castor oil 40 g (5%)
Add after Trace
- 1.41 oz Mango butter 40 g (5%) – this is the superfat
- 6 tsp Grapefruit essential oil 24 g / 0.85 oz
- 1 TBSP Yogurt 15 g
Instructions
Prepare your Soap Making Station
- Ensure that your kitchen workspace is clean and set up with all of your tools, ingredients, and equipment. Please also prepare yourself by wearing long sleeves, closed-toe shoes, goggles, and plastic gloves. Soap making is fun but also chemistry so you need to work safely. I'd also advise that you make soap when smaller children aren't around put pets in a closed room somewhere. It's best to work undistracted, and you want to keep them safe.
- Plug the crockpot in and turn the heat to high.
- Pre-measure all of your ingredients. The solid oils into a saucepan, the distilled water into a heat-proof jug, the lye into another jug (or glass jar), the essential oils into a small ramekin, the yogurt into another ramekin, and the additional mango butter we're using as the superfat into a third ramekin.
Make the Lye Solution
- Put on your goggles and gloves, and make the lye solution. You should do this in a well-ventilated area and try not to breathe in the steam. I like to work outisde for this step or next to an open window. Measure the sodium hydroxide (lye) into a container and the distilled water into a heat-proof jug.
- Pour the sodium hydroxide into the water and stir very well. It will be very hot at this point so be careful. Set the jug someplace safe and leave the lye mixture to cool to around 120°F (49°C). You can set it in a sink, basin, or large bowl filled shallowly with water. If it's winter, it could be enough to set it in a safe place outside.
Melt the solid oils
- Though you can melt the solid oils in the slow cooker, it takes a long time. To speed things up, place the pan of solid oils on the hob and turn it on to the lowest heat setting. They will melt quicker than you expect, so stay with the pan, moving the oil around in the pan to help speed up melting. When there are a few small pieces of solid oil still floating, take the pan off the heat and set it on a potholder. They'll melt with the residual heat and some gentle stirring with your spoon/spatula.
- When completely melted, pour the oil into the slow cooker. To minimize air bubbles getting in, try pouring the liquid oils onto a clean spatula held over the pan of oils. Do this each time you add something new to the slow cooker.
Add the liquid oils
- Next, pour the liquid oils into the slow cooker with the melted oils. Use the spatula to get every last drop out of the jug then stir the oils together gently.
- Take the temperature of the pan of mixed oils. You're aiming for around the same temperature as the lye solution, but they can be a few degrees within 120°F (49°C)*.
Bringing the Ingredients to 'Trace'
- When the temperatures are right, pour the lye solution through the sieve and into the oils. If you want to minimize air bubbles, set the immersion blender in the crockpot at an angle and slowly pour the lye solution somewhere along the head-end.
- Carefully place the head of the immersion blender (stick blender) into the oils. Insert it at an angle so that any air inside the head can escape as you submerge the head. Air trapped inside the head can create air bubbles in your soap.
- The next step, bringing the ingredients to trace, is best shown in the video at the bottom of this recipe. Have a watch to understand all the steps better, but especially this one. If you're a cold-process soapmaker, this step is exactly the same as bringing the soap to trace for that method.
- Stir the contents of the pan gently, using the immersion blender as a spoon. Then bring it into the center of the pan and hold it against the bottom of the pan. Not moving the immersion blender, pulse for a couple of seconds. Then gently stir. Keep repeating this pulse then stir process until the soap thickens to a medium trace — it will have the texture of warm pudding. Stop blending, tap off the immersion blender's head, and put it aside. You will not use it again.
Cooking the soap
- The next step is cooking the soap. Turn the heat setting on the crockpot to low, and using your spatula, gently scrape all the soap residue from the sides down into the main batter. If you don't, this thin layer can turn crusty pretty quickly. Next, place the lid on and leave it to cook for thirty minutes. Do not take the lid off during this time or it will release moisture. You need your soap batter to be fluid for the next steps.
- Over the half-hour, the soap batter will begin to puff up a bit around the edges and its texture will change. The soap in the middle will appear opaque and creamy, whereas the hotter soap on the outside will look glossier and more vaseline-like. You're aiming for all of the soap to have the glossier texture.
- After the time is up, look through the lid of the slow cooker. If you see an opaque center still, keep cooking, and set a timer for fifteen minutes. Slow cookers vary so while it takes my model 45 minutes to cook the soap, others might take less or more time.
- Once all of the soap batter resembles vaseline, you can turn off the heat, take the cooking vessel part out of the slow cooker, and set it on a potholder. Gently stir the outside edges towards the center and mix well but avoid stirring any crusty bits into the soap. They'll show up in your final bars as white lumps. Take the soap's temperature next. It will be very hot, and you need it to be just under 180°F (82°C) before you add your next ingredients. While the soap is cooling, it's best to keep the lid on the vessel. It slows down the cooling time, but it also keeps the moisture in the soap from evaporating out.
- Just before the soap is cooled enough, melt the mango butter superfat. You can use the same pan that you used earlier to melt the other solid oils.
After the cook
- When the temperature of the cooked soap is right, stir in the melted mango butter, the essential oil, and the yogurt. Mix it in gently but thoroughly.
- Spoon the soap batter into the silicone loaf mold while it's still fluid. After each spoonful, tap the mold to settle the soap and to help release any trapped air bubbles. This batch should fill a 28 oz loaf mold perfectly — the inner dimensions of mine are 8×3.5×2.5"
- Leave the soap to cool and harden for at least twelve hours. Afterward, measure and cut the soap into bars of whatever size you'd like.
- Though hot process soap is fully saponified after the cook, you should cure it for a full four weeks (at least) before using it. To cure your soap, set the bars on a piece of grease-proof paper (or baking paper), in an airy place out of direct sunlight. Leave the soap there to dry out and to help excess water to evaporate from the bars.
- After the cure, use the soap or wrap it up in these eco-friendly soap packaging ideas and give as gifts. Your soap should be stored in an airy place until you use it, and to find its shelf-life, look at all of the bottles of ingredients you used. The closest date is the best-by date of your soap.
- Watch the full video below to see step-by-step how to make simple and moisturizing hot process soap.
Video
Notes
More Soap Making Inspiration
- How to Rebatch Soap the Easy Way (No Slow Cooker!)
- Liquid Soap Making from Scratch
- 7 Ways How to Make Soap (Easiest Method to Most Advanced)
- Make this Pure Coconut Oil Soap Recipe
I doubled this recipe for hot-process soap, and used lavender essential oil. I found the soap came out with a soft oily texture, and this happened previously with cold-process lavender soap. Is there something about lavender oil that is chemically influencing the hot-processed soap?
Hi Erin, and no, lavender essential oil doesn’t have that effect on soap and I’ve never heard of anyone having this issue before. Are you sure you’re using a true essential oil and not a synthetic fragrance oil though? Check the bottle carefully. Also, I wonder if you might be adding too much fragrance or if your measurements in general are correct. Perhaps check that the digital scale you’re using is functioning properly and that all your ingredients are correct, too.
Hello, Tanya,
First, thanks so much for your great book. I haven’t finished it, but I’m enjoying it bit by bit.
Second, thank you for this recipe. I consider myself more of an advanced beginner – I’ve been making hot process soap and also shampoo bars for probably 8 years, but I have stuck closely to my few proven recipes and they are basically just for my own use (though my adult daughters have enjoyed them also!). I will try this one out for a change of pace, and I have learned some new tricks from your video that I’ll be using from this point forward no matter what kind of soap I’m making!
Thank you again – you’re terrific :-)
You’re so welcome, Robin, and I’m very pleased to help :) Glad to know that the video has been useful!
Hi. I really like your hot soap recipe with the Mango butter. I want to make soap using the cold process soap method and use Mango fruit instead of Mango butter. I want to upscale the batch to be a 5 pound soap in which I will be using a lined wooden loaf mold.I have to increase in all the ingredients accept I don’t want to usecyogurt. How much Mango fruit to use?
Hi Charmaine, mango fruit is not a substitute for mango butter and they are two completely different ingredients. Though you cannot leave the mango butter out of this recipe, you could add mango puree as a replacement for the yoghurt in the same quantity. I also highly recommend that you make this soap in a smaller amount before committing to a larger one. That way you can understand how to make soap and have a grasp of what to expect. If anything goes wrong, you won’t have lost out on the value of your ingredients. Good luck :)
Hi Tanya, I really enjoy your lovely greens channel.
I make my own home made “tart Greek style” coconut yoghurt using lactic acid bacteria. Would this have sufficient lactic acid to substitute as a vegan alternative to Greek yoghurt in your hot process soap making? Cheers, Marion
Hi Marion, and though I’ve never tried it, I think it would be fine to add after the cook. It sounds delicious by the way!
Hi
Do I have to use the mango butter.
Yes :)
Hi, is there a reason why I can’t find anything on the Cold Process Oven Process soap on your site? I remember a friend telling me a few years ago that she doesn’t make it because she doesn’t want to bake food where NaOH was, so I was wondering how safe it is?
Hi Petra, if you’ve ever used an oven cleaner then you’ve used NaOH directly on your oven :) It’s perfectly safe to oven process your soap in the same oven that you use to make food
Can this soap recipe be doubled to fill a mold much larger than the one you used? Thanks for the info. Love your website!
Carol T
Hi Carol, and yes, feel free to scale the recipe up :)
Newbie here. I love hot process soap as it looks so rustic. I made this one last night & it seems to dry my skin out. Could it be that I added lemongrass EO? I plan on trying all of your soaps.
Hi Doris, though technically you can use HP soap right away, it becomes milder after a full month’s cure (at least). Curing is not an optional process for hot process soap — it’s important to wait so that the soap’s full crystal structure has formed before you know the true quality of the soap.
Hi Tanya I had never made soap ever, but after watching your video on YouTube, I was encouraged to try it. I followed the step by step instructions and it was a success, it worked like a charm. My husband loves it too and stopped using regular store bought soaps. It is very conditioning to the body and we don’t get that dry feeling. Thank you so much for the tips and the soap recipe!
You are SO welcome Teresa! So pleased to hear of your success in soapmaking :)
I would lie to add some Beeswax to my soap…how much could be added to your recipe?
Thanks!
Hi Carol, here’s more information on making beeswax soap
Quick question, is it possible to not put the yogurt so as to make it vegan?
Yes, that’s perfectly fine to omit the yoghurt
This was my first batch using lye. I’ve always did glycerin soaps, as I was always afraid to work with lye.
Loved this recipe, easy and simple, the only thing is that I substituted the castor oil with safflower oil, and use 1 tsp of sodium lactate instead of yogurt. After cooking the soap I poured poppy seeds as I used strawberry guava fragance oil, and poured on silicon molds. They turned out wonderful.
Hello!
Thank you for your fantastic instructions, I have made cold process soap but not hot.
My question was could I use this recipe as a cold process as long as I cure it for longer? And if I can would it be best to add the super fat mango butter in with all the ingredients or after trace?
Thank you!
Looking forward to receiving your gardening book when it comes available?
Hi Susie and yes! Most people don’t realize that you can make most from-scratch soap recipes using either cold or hot process. If they’re simple soaps that don’t require swirling, layering, or cool temperatures, then you can use the method of your choice. One difference is the water quantity. For hot-process you need full water (lye amount x 3) and in cold-process you don’t need as much. My preferred amount of water for cold-process can be calculated by multiplying the lye amount by 1.8. As for the superfat, you can do it either way :)
If you are doing High Temp Hot Process you can still swirl as you do with cold process. I love hthp soaping.
Hi Tanya, somebody posted this comment before and the reply was, watch the video, but actually still not sure, in the recipe instructions you add the mango butter superfat after the mixture has cooked however in the video you add it before. Which is correct please? Thanks.
I am a fan of all your recipes and of everything about your gardening and soap making and creams making, I simply love the recipes and tried more than one.
IN this HP soap recipe though, the soap bars are a bit soft and quite spongy even after 2 weeks, is that normal?
I have downloaded the Natural Soap Making Guide, delighted !, looking forwards to an HP soap secrets book from you, thanks for everything
Hi Anaida, and apologies for the confusion. The answer is that you can add all of the mango butter before the cook or reserve 5% (total weight of main soaping oils) of it to add afterward. The difference is that if you add this portion of mango butter after the cook, you can be 100% sure that the superfat (extra oil) in your soap will be just mango butter. If you add all of the mango butter in before the cook, with all of the other oils, then the superfat of your bars will be a combination of all the oils used. Does that make sense?
In the video, I added it all before the cook because it cuts out a step for beginner soapmakers. It also is one last thing for beginners to have to remember to do, and I’ve had dozens of emails from people over the years asking what to do if they forget to add an oil/the superfatting oil. That’s why nearly all of my cold-process recipes don’t include a superfatting step. After second thoughts, I decided to share the proper way of adding the superfat in after the cook for the printed version of this recipe. Either way works though :)
Hi Tanya , Thanks for your quick reply, I have tried adding the superfat at the end as per the written recipe ( in the video it’s added at the trace ) but I have thought maybe I have done it wrong as the soaps are kind of soft and spongy even after 2 weeks, will let them cure a bit longer and maybe next time I will try adding the superfat at trace, as per the video and see the difference. Soap is so nice, so creamy. The first soap I ever made was after your recipe too and it was Castile Soap, and I intend to do again one of your CP recipes, I love a lot the Sweet Orange one!
Thank you again for sharing with us, I am sure that many of us started a soap business following your recipes ( and your smile ), we do trust you.
Wishing you Happy Gardening and Happy Soapying.
Reading this has made my morning — thank you Anaida ?? I was a little hesitant about how to spell the superfat out for folks in the written recipe. With written instructions, it’s easier to read through and do things the “proper” way. I might just change it back to simply adding the superfat before the cook. It does make it simpler, even if the superfat doesn’t end up being 100% mango butter.
Hi this is Alma, I love your page, I really like your way of being.
Have a question
something happens if the mixture took an hour and a half to be ready in the slowcoker? will it be the same product in the end?
Slow cookers sometimes differ in temperature, especially if the slow cooker is older. If in doubt, just pour the soap into molds and wait out the full 28-day cure time before you use it. All soap, including hot process, benefits from a long cure time anyway :)
Hello I have a question what brand of essential oils you use?
Mainly Naissance essential oils
How and when do I add color?
Hi Tiffany, you usually add it after the cook but it can be before (just after trace), depending on the colorant and your preference. I’d add anything that can be affected by long periods of heat after the cook (for example, purees), and ones that are unaffected by heat or benefit from it before the cook (such as mineral pigments).
Great! Ottimo video, chiaro e davvero utile.
Mille grazie, di cuore.
So is it 1.41 oz of melted mango butter with the base oils AND an additional 1.41 oz as superfat at the end? 2.82 total ounces? Thanks.
Yes Phyllis
Hi Tanya, in the recipe instructions you add the mango butter superfat after the mixture has cooked however in the video you add it before. Which is correct please? Thanks.
Hi Kelly, part of the mango butter goes in to with the base oils and part of it is reserved for melting and adding as a superfat. You’ll see that a bit further on in the video :)
If I use your calendula tallow recipe for hot process soap. Can I still add the mango butter superfat and yogurt? What is the best way to determine how much superfat can be added to the recipe?
Hi Tammye, you do not need to recalcuate cold-process soap recipes when making them using the hot process method. The base recipe stays the same, and only the way you make it changes — so don’t add the mango butter. Saying that, you do need the full water amount when making hot-process, so make sure you calculate that in. And yes, you can add the yogurt to any recipe.
Thank you for your recipes – you’ve introduced me to soap making with a fair amount of success so far and we’ve been enjoying the moisturizing skin benefits :). Now I’d like to try this hot processed one, but don’t want to use mango butter (not so easy to buy) and already have the other oils – is there anything else that would do instead – have got rapeseed oil, almond oil, olive, coconut and castor in my store. Would tallow work as well? Thank you
Hi Moira, you can use pretty much any cold-process soap recipe to make hot process soap. The only thing that you need to change is the water amount. One easy way to calculate enough water is to multiply the lye amount in a recipe by three.
Awesome article! Thank you sharing your knowledge with us
Hi Tanya,
Just love your instructional videos and lovely recipes. I am new to soap making and after curing my soaps, they loose all scent.? also I would very much like to customize my own. Would your soap calc be a way to regulate ingredients?
Lastly, did I hear correctly?… you can use same exact recipes from cold process to make hot process soaps?
Thank you for your generosity
Regards Donna
Hi Donna and as a beginner, I highly recommend that you not try to create your own recipes. There’s a lot that goes into formulating them and right now you should focus on honing your skills at making soap rather than making recipes. Few people who start baking decide to come up with their own cake recipe from the get-go :) For more info on changing and customizing a soap recipe head over here.
As for your second question — yes, you can use practically any from-scratch soap recipe in either cold or hot process. You need the full water amount for hot process though, as explained.
I’ve been wanting to try soapmaking for a long time–it’s the main reason I get your emails–but I have a question about ingredients that a quick Google search didn’t answer: Can I substitute 1:1 the hemp butter I already have for the mango butter in the recipe? How do I figure that out?
Hi Jena and no, you cannot usually substitute one oil/butter for another in soapmaking. That’s because each oil and butter has a different SAP value. Meaning, it needs a different amount of lye to be transformed into soap. Also, hemp butter is not a pure oil and made with hemp seed oil mixed with other oils (such as linseed) to give it firmness. It’s not easy to give it a SAP value because each brand you buy will have a different blend of oils. You should definitely read my piece on how to change and customize a soap recipe.
This may be a goofy question (newbie here), but do you need to have a crockpot that is designated solely for soapmaking? Or does the sped up saponification take care of any residual lye in the crock?
An ordinary crockpot will do :) Also, at the end of the process, the ingredients in the pot are pure and natural soap and wash out easily.