While there are other methods of making soap (hot process and melt & pour), this soap making 101 tutorial provides a basic overview on how to make soap the cold process way.
It will be added to my Natural Soap Making page along with other helpful links and recipes; so be sure to bookmark or pin it for easy reference.
Making soap is one of my favorite hobbies. There are so many ways to personalize a single recipe, that I rarely make the same soap twice! Once you get the hang of it, you’ll never want to go back to store-bought again!
What is cold process soap?
Cold process soap is made without any external heat applied to it, while hot process soap is most often cooked in a crockpot to speed up the soapmaking process.
For more in-depth information, 60+ palm free recipes, helpful charts, plus a private Facebook support group, check out my Natural Soapmaking Ebook Collection.
Soap Making Notes
Many people are afraid to make soap because it involves handling lye. I know that feeling, because I was the same way! I had my husband do that part at first until I got more comfortable with the idea. Lye requires caution, but you also just need to employ the same common sense you’d use for any potentially dangerous situation such as cooking with a hot stove, or driving down the road in your car.
Handle the lye with proper protective gloves and eye wear along with a healthy dose of respect. Do NOT involve your children in this activity. There are other fun ways they can “make” herbal soap; check out this post on Making Soap Without Handling Lye.
Read my blog post “Why do you need lye to make soap?” for more information and tips on safe handling.
An accurate digital scale is essential! Don’t measure soapmaking ingredients by volume (cups, tablespoons, etc) as it’s just not accurate enough.
My in-depth troubleshooting guide, “What’s Wrong With My Soap?“, will help you find solutions to 30+ common soapmaking problems you may run into.
Some links on this site are affiliate links. If you click on one and make a purchase, I earn a small commission for sending a customer their way. I only recommend products I’ve personally used and like. Thanks! :)
Okay! Now, we’re ready to start learning how to make soap!
12 Steps to Make Cold Process Soap
1. Choose a recipe and run it through a lye calculator.
You can find a bunch of tried and true soap making recipes on my Natural Soap page or in my Natural Soapmaking Ebook Collection. Running the recipe through a lye calculator is important if you decide to make changes since each type of oil requires a different amount of lye to saponify (turn into soap.) So, if you’re out of the castor oil called for in a recipe and want to use shea butter instead, you’re probably going to need a different amount of lye or your soap will end up too harsh or too soft.
I like to use the Majestic Mountain Sage or Soapee’s lye calculators because they’re both user friendly. Just plug your recipe into the blanks and calculate the lye needed. I like to use a 5 or 6% superfat for most recipes.
2. Assemble ingredients and safety gear.
Lye is sometimes hard to find. A hardware store near me carries ComStar and I also order Red Crown High Test Lye or Essential Depot Lye from Amazon. If buying locally, shake the bottle and if you hear lumps and clumps rattling around, it’s past its prime and won’t weigh out correctly.
There are many online vendors to buy oils and butters from, but you can also check your local grocery and health food stores. Don’t forget you’ll need heat & chemical proof gloves and safety goggles along with a thermometer.
Read through my List of Equipment You Need to Make Soap at Home for a complete rundown of the gear you’ll want to have on hand before you begin.
3. Prepare the mold.
If using a loaf or box mold, line it with freezer paper or parchment paper.
I use homemade wooden molds, but you can also buy them from several places online. I’ve also seen people use rubbermaid containers, heavy duty cardboard boxes, and silicone bread loaf pans.
If you want to make your soaps extra pretty, check out my list of 15+ Pretty Silicone Molds for Making Handmade Soap.
4. Weigh the water.
First, measure out the water into a stainless steel or heavy duty polypropylene plastic (recycle symbol 5) container. [NOTE: In the past I’ve used glass or pyrex, but it sometimes shatters, so I no longer use it for this step.] Mark this container clearly with a symbol such as a skull and crossbones and don’t put it in your fridge or on the counter where someone might mistake it for a beverage.
All soap ingredients should be weighed with a digital scale, this includes your liquids. Oils and lye weight must be exact. For liquids, you have a little bit of play room. I like to use a reduced amount of water/liquid so my palm-free soaps firm up faster and are easier to unmold.
5. Weigh the lye.
(Wear those gloves and goggles!)
I use an old plastic cup, labeled “Lye” in several places all over with a Sharpie. I pour slowly and carefully then immediately re-cap the lye container and place it far from the reach of children and pets. Wipe up the area with a damp paper towel to make sure you catch any stray grains that spilled when you poured.
6. Pour the lye into the water.
I do this in my kitchen sink in order to catch any splashes or drips and just in case I have a “volcano.” This only happened to me once because I tried to pour my lye into a very hot herbal tea. I should have been patient and waited for it to cool first, but did not and had to start all over. So, make sure you pour the lye into water that is cool or no warmer than room temp.
Always add the lye to the liquid and not the other way around. Lye + water shoots up to over 200 degrees F quickly, so use caution when handling. Turn your face away to avoid directly breathing in the fumes. I keep the window over my kitchen sink opened during this step or work outside on my back deck. If you don’t have proper ventilation, consider wearing a mask. Stir with a heavy duty plastic spoon or rubber spatula until fully dissolved and set in a safe place, out of reach of children and pets, until it cools to about 90 to 115 degrees F.
7. Weigh and heat the oils, butters & fats.
Do this while the lye solution is cooling.
You can either heat everything together in a stainless steel soaping pot and then let it cool to 90 to 115 degrees F.
Or, I like to melt the solids (coconut oil, babassu oil, tallow, cocoa butter, shea butter, etc), then combine them with the liquid oils. This usually warms everything up enough, but if needed you can heat the mixture a little longer until the combined oils reach 90 to 115 degrees F.
8. Monitor the temperatures & combine.
Try to get your oils and lye solution fairly close to each other, but it’s completely fine if they’re 10 or even 20 degrees different. I sometimes add an ice cube or two to my lye solution to cool it faster (remember the water amount can be adjusted by this small amount) or set my pan of oil down into a sink filled with a few inches of water and ice cubes if it needs quicker cooling.
Temperature is a subjective, personal preference that varies between soap-makers. Some will only mix at higher temperatures than I list here, while others let everything sit overnight and mix the next morning at room temperature. Both ways are fine to use!
Once the desired temps are reached, slowly drizzle the lye solution into the container of oils and butters.
9. Blend until trace.
Using a stick blender, blend the soap in short bursts of a few seconds at a time, stirring by hand with the motor off in between times. Don’t run the stick blender continuously or you may burn out the motor and your soap will thicken up too quickly.
It should only take a few minutes for most of my recipes to reach “trace”. (Trace means when you drizzle a small bit of the soap mixture over the surface of itself, it will leave a faint pattern or trace before sinking back into the mixture. The photo above demonstrates trace.
Your stick blender should be used strictly for soap making and not for food use. Once trace is reached, add any extras such as honey, oatmeal, natural colorants, and essential oils and hand stir/blend for just a bit more until they are all incorporated.
10. Pour the soap batter into the mold.
Working quickly, pour the soap into your prepared mold, smoothing the top with a rubber spatula or wooden spoon if needed. Pick up the mold and give it a few sharp raps on the table or counter surface to help get rid of any little air bubbles that may have formed.
The soap is still caustic at this point, so keep your gloves on and be aware that raw soap batter can burn your skin. If that happens, rinse thoroughly with cold water.
11. Cover and insulate the mold.
This keeps the soap warm so that it can go through gel phase and finish saponifying.
(If making soap with milk, it needs special treatment and won’t need covering. Read “How to Make Soap with Milk” for more information.)
Leave undisturbed for about 24 to 36 hours. (It’s okay to peek at it every now and then though. If you spot a crack forming on top, it means the soap is too hot and should be uncovered.)
12. Unmold and slice into bars.
You can cut the soap into bars right away or later. I like to do it fairly soon after making, so that the soap is still easy to cut.
Use a knife or you can use a wire soap cutter like the one shown above. (You can buy wire soap cutters HERE on Etsy.)
Let the bars of soap cure in the open air on pieces of wax paper, turning occasionally, for at least 4 weeks.
And that’s how to make your own soap, from scratch!
Did you enjoy learning how to make soap using the cold process method? If so, let’s keep in touch!
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