How to Make Natural Hot Process Soap: Recipe + Tips

Soaps are one of the most common things we expose ourselves to daily. We use soap to clean our skin from pollutants and dirt that build up throughout the day to maintain optimal skin health and beauty.

How safe are the soaps we use every day?

Synthetic Soap: Daily Exposure, Harmful Consequences

We should understand that most synthetic commercial soaps, including the leading brands, have ingredients and chemicals that are absorbed by our skin and could be harmful.

Why lather ourselves with synthetic harmful chemicals day by day when we can make our own natural soaps at home? Or, if pressed for time, there are plenty of high-quality natural soaps available online and maybe even locally, depending on where you live.

Reducing chemical exposure is the key to natural skincare and it’s easily achieved in most cases with a just few simple practical steps.

• One of those steps is making the switch to natural soaps. Soapmaking is incredibly enjoyable and puts you in control of exactly which ingredients end up on your skin.
• Commercial soaps include a variety of ingredients: parabens, phthalates, artificial colorings, and synthetic perfume that can irritate and even negatively impact skin health.
• If we want healthy and beautiful skin, it goes without saying that using these chemically-ridden soaps may be counter-productive.

Introduction to Making Natural Hot Process Soap

Fortunately, the process of making natural and homemade soaps is becoming more popular.

Due to increased popularity, people are getting more creative, and more varied recipes are being formulated all the time. Natural soaps can contain any number of carrier oils, essential oils, honey, oatmeal, aloe, and other organic ingredients. 

True to its name, hot process soapmaking is a method carried out under higher temperatures. This distinguishes it from the traditional cold-pressed artisanal process.

The heat speeds up the saponification process, converting oils into soap more rapidly and allowing for immediate use. As appealing as it sounds, the process does require some degree of precision and caution, resulting in beautifully healthy soaps brimming with your own personal ingredient preferences (scents, flower petals, you name it!), natural ingredients, and eco-friendliness.

Why Make Your Own Soap? 

Before we embark on the journey of soap creation, let’s answer a simple question. Why would it be worth the time to create soap at home? Why not just buy a bar from the nearest store? Well, there are a few compelling reasons: 

1. Gentleness on Skin: Commercial soaps often contain harsh chemicals and synthetic ingredients that can strip your skin of its natural oils. When you make your own, you know exactly what’s going on in it. This control allows for the creation of a soap tailored to your skin’s specific needs.
2. Environmentally Friendly: Homemade soaps don’t just benefit you; they’re better for the environment as well. With no synthetic ingredients, the product is biodegradable and free from harmful pollutants. Additionally, natural ingredients can be manufactured more sustainably than synthetic ingredients, which often results in the disposal of toxic byproducts. 
3. Creative Outlet: Soapmaking is not just practical – it’s a chance for you to express your creativity. Experiment with various essential oils, patterns, colors, and textures to create your unique bar.

“Making soap at home is a satisfying and incredibly inexpensive. Homemade soaps are tailored to your family’s preferences and make for meaningful creative gifts.”

As you’re probably already aware, there are some great companies that sell all-natural soaps found in stores that offer natural and organic beauty products. Of course, the options online for natural soap products are endless as well.

Lastly, we have a great Oatmeal Milk and Honey Soap article that includes 3 easy recipes. They all use the melt-and-pour soapmaking method, where you’ll be starting with a premade soap base rather than making your own from scratch, as in the hot and cold process soapmaking methods.

But why settle for only store-bought soaps when you can enjoy the experience of using your own creativity to formulate a new scent, color scheme, or lather preference? That’s right, all of that’s up to you when you make your own soap and more. 

Common Ingredients in Natural Homemade Soap

Below, see a shortlist of a few commonly used ingredients classified across five categories.

Base Oils and Fats

Lye (Sodium Hydroxide)

Essential Oils

Additives

Natural Colorants

The number of potential ingredients you can implement into your own soaps is almost endless. That also means endless scent profiles, moisturizing qualities, and skin benefits as well. So, these are just some of the most common ingredients you may come across in soapmaking, but again, you can make some wonderful benefit-packed soaps when you control what you put into them.

Yet, as inspiring as experimenting can be, safety comes first. Please never underestimate the importance of safety when handling lye (more on that later).

Whether you desire certain unique scents, textures, colors, sizes, or shapes, it’s all completely dependent upon your own ideas and tastes. Who knows, you might become the next small-town soap artisan!

Understanding Hot Process Soapmaking: At a Glance

Hot process soapmaking, also known as HP soap, is a method of making soap that involves heating the soap mixture to speed up the saponification process. This method is different from the cold process method, which involves allowing the soap to saponify at room temperature.

• The hot process method has been used by soap makers for centuries. It is a popular method because it allows for a quicker turnaround time and produces a soap that is ready to use immediately. However, hot process soapmaking requires more attention to detail than cold-process soapmaking (temperature measurements, stirring stages, etc.).

• To make hot process soap, we first mix our oils and lye solution together. We then heat the mixture in a pot over low heat while stirring constantly. As the mixture heats up, it will start to thicken and turn into a gel-like consistency. This is the saponification process happening.

• Once the soap has reached trace (the point where the mixture has thickened and the oils and lye have fully combined), we transfer the mixture to a slow cooker or crockpot. We then cook the soap on low heat for several hours, stirring occasionally.

• During the cooking process, the soap will go through various stages, including a jelly-like consistency, a mashed potato-like consistency, and a crumbly texture. When the soap reaches a smooth, uniform texture, it is ready to be molded.

• Hot process soapmaking requires more attention to detail than cold-process soapmaking because the soap mixture is heated and can easily burn or overcook. It is important to monitor the soap closely during the cooking process and stir it frequently to prevent it from sticking to the sides of the pot.

Hot process soapmaking is a popular method of soapmaking that produces soap that is ready to use immediately. However, it requires more attention to detail than cold-process soapmaking and can easily burn or overcook if not monitored closely. With practice and patience, anyone can master the art of hot process soapmaking.

Safety First: Working With Lye

When it comes to soapmaking, there are basically two different methods that can be used: hot process and cold process soapmaking methods. Both methods utilize chemical reactions from lye, and both must be used with caution. Soapmaking is a chemical process.

All Lye will be expended once the chemical reaction necessary to make your soap is complete.

Whenever working with any kind of chemical or naturally potent ingredient (that includes essential oils), always take the necessary precautions. Gloves and safety glasses/goggles are often recommended when working with lye. When the necessary precautions are taken, working with lye is very safe.

A Brief Note on Lye (Sodium Hydroxide):

Before we get into the details of making soap, a few things need to be addressed. Do you remember those days in chemistry class when your teacher would introduce a new chemical to be used before performing an experiment?

Remember the warnings about the volatility of that chemical?

• Lye is an ingredient that is both volatile and dangerous if not handled properly.
• You don’t need to be a trained chemist to have fun making your own soap, but you do need a blend of common sense and caution.
• Never use aluminum materials when working with lye since it’s a reactant.

In the same way that it’s enjoyable to do experiments in chemistry class, there is fun to be had when making soap at home. Again, caution is always advised whenever working with harsh or volatile ingredients like Lye.

Lye, also known as Sodium Hydroxide (or caustic soda), is safe when handled properly.

Note: Potassium hydroxide (aka caustic potash) is used for soft and liquid soaps and won’t be used in the recipe dealt with today. For all hard soap recipes, be sure to purchase 100% sodium hydroxide. Do not use liquid Lye.

Driving a car can be done safely when caution is used, and the same is true when working with Sodium Hydroxide. Many people are afraid to use lye, but that’s due to cases of improper use and misinformation. Also, once the chemical reaction in your soap mixture is finished, no Lye will remain.

If not handled with caution, this potent ingredient has the potential to burn the skin and cause damage to the eyes.

Lye Safety Precautions:

• Use PPE (Personal Protective Equipment) like gloves, safety goggles/glasses, long sleeves, or a lab coat (if you want to have the mad-scientist look)
• Keep a container of vinegar near your workspace since it will neutralize the Lye
• Use heat-proof containers that will not crack or melt
• Never lean over your mixture while working
• Work near a water source so you can flush any part of your body that may come into contact with lye
• Cover your work area with newspaper to prevent unwanted spillage from coming into contact with your floor or counter
• Wash hands and arms thoroughly when you’re finished making your soap (a single grain of lye can cause irritation)
• Whenever working with any potent ingredients, never leave the area unattended
• Keep children and pets out of your work area
• Always store potent ingredients properly in an area where pets and children cannot access them
• Never use aluminum when working with lye.
• Always add lye gradually to the water
• As a mixing rule, never add water to lye; always add lye to water
• Never allow lye to settle in your container while mixing it into water

Preparation

Making your own natural soap is pretty simple. Just follow the simple steps on this page, and you’ll have a blueprint to use for experimenting with whatever your heart desires when it comes to creating breathtakingly fragrant and attractive soaps.

Oh, by the way, don’t be nervous if this is your first time making soap. You might mess up, you may not get the consistency you want, you may include too much or too little fragrance, and so on. Whatever the case, the experimentation is the fun part!

But before we begin, you’ll need to assemble all the necessary equipment.

Essential Materials and Ingredients

Equipment:

• Digital Kitchen Scale
• 2 Commercial-Grade Heat Resistant Pitchers (Stainless Steel or Enamel, NOT Aluminum!)
• Digital Food Thermometer
• 2 Stainless Steel Long-Handled Serving Spoons
• Electric Hand Mixer or Immersion Blender
• 8oz  Disposable Plastic Cup
• Silicon Soap Mold
• Measuring Spoons
• Rubber Spatula
• Safety Items and PPE (Personal Protective Equipment)
• Crockpot

-A digital scale is essential for measuring the precise amounts of ingredients needed for soapmaking.

-A stick blender is used to mix the oils and lye solution together.

-A soap mold is used to shape and cut the soap into bars. A crock pot is used to heat the soap mixture during the various stages of the cooking process.

-A double boiler is used to melt ingredients such as cocoa butter.

-A swirling tool is used to create swirls and patterns in the soap.

-A silicone spatula is used to scrape the sides of the crock pot.

-With these basic ingredients and additional tools, you can easily make your own natural hot process soap at home.

Next, let’s take a look at some of the core ingredients. Different recipes will use varying ingredients. So, it’s never a bad idea to see which kind of base formula suits your preference after a few successful attempts at soapmaking.

Ingredients:

• 4 Ounces of Castor Oil
• 8 Ounces of Olive Oil (Pomace, Not Virgin)
• 8 Ounces of Palm Oil
• 8 Ounces of Coconut Oil Melted in 76 Degrees
• 10 Ounces of Distilled Water
• 3 Ounces of Lye (Sodium Hydroxide)

This recipe will leave you with a solid soap with a superfat value of 1%.

The superfat value refers to the amount of oil that won’t be ‘consumed’ during the chemical reaction with lye. That means the remaining oil will be left over in the mixture to moisturize the skin in the finished product.

• Feel free to add additional oil for a higher superfat value.
• You can use this calculator from Bramble Berry to hone in on your exact process.
• I recommend starting with the above recipe first, then modifying once you’ve gotten the overall hot process steps down.

The Process: Fat + Lye = Soap!

Cold Process Soap:

This process utilizes oils like olive oil. The oil is placed into an enamel or stainless steel container, then a mixture of lye and water is added to the oil and stirred until slightly thickened and “trace” is reached. Once thickened, the mixture is then poured into a soap mold and left to harden.

Usually, after a few weeks, the soap is ready to use.

Hot Process Soap:

This process is very similar to the cold process but causes the soap to be ready to be used in just a matter of days instead of weeks. With the hot process, the steps are pretty much the same as the cold process up to the point of pouring the mixture into the soap mold.

• Instead of pouring the mixture into a mold at this point, the mixture is cooked for a specified amount of time to drastically decrease the curing time of the soap to around 24 hours for best results.
• Technically, hot process soap can be used pretty much immediately.

The main reason that soap makers choose hot process or cold process soapmaking is personal preference.

• Some soap makers prefer hot process soapmaking because it allows them to use the soap immediately and doesn’t require a long cure time.
• Other soap makers prefer cold process soapmaking because it gives them more control over the process and allows for more intricate designs and fragrances, though it can take 4-6 weeks to cure.

Soapmaking Instructions: Follow These Steps Carefully

1. Mix the lye and water.

Place an empty non-aluminum (plastic or glass) cup on a scale. Put the exact amount of lye (3 oz) in the cup and set it aside. Next, place a pitcher on the scale to pour the water into. Measure 10 oz of distilled or purified water and remove from the scale.

Then, gradually add the lye into the water and slowly mix them using a long-handled serving spoon until the lye is dissolved. Remove the pitcher from the scale.

2. Mix the oils.

Next, place an empty pitcher on the scale. Accurately measure 8 oz of coconut oil and reset the scale to zero. Add 8 oz of palm oil and again reset the scale to zero. Next, add 4 oz of castor oil (reset scale to 0).

And finally, add the other 8 oz of pomace olive oil. Now that all the oils are measured and combined heat the oils in a double boiler on medium or in the microwave.

You can heat them on a stovetop as well, but just be sure to melt them slowly and not use high heat. Stir well to mix them. Heat them until they reach a temperature of about 120°. Check the temperature regularly with your digital thermometer.

3. Add the water/lye mixture to the oils.

This step is probably the most difficult, but it’s actually quite simple. Your digital thermometer is your friend! You can perform this step by periodically checking the temperature of the water/lye mixture and oil mixture using the digital food thermometer.

Once each of them has cooled to a temperature between 95° and 105°, they can be mixed in a warm (not hot) crock pot. 

Slowly pour the water/lye mixture into the oils. It’s a myth that they must be within 10° of each other prior to mixing, but it can help to ensure they mix more uniformly.

Note: If you combine both mixtures when they’re too cool, they’ll come together too quickly and be crumbly and coarse in consistency. Even if they aren’t cool, you can run into the issue of false trace.

4. Mix the oil and lye mixture together.

Submerge the stick blender into the oil/lye mixture and pulse for a few seconds. Stir the mixture and pulse again. Alternately stir and pulse the mixture until it becomes as thick as pancake batter. This procedure will take about 3-5 minutes. As an alternative, you can mix them with a handheld whisk, but it will take you longer to reach that pancake batter consistency.

5. Mix until it reaches the “trace”.

Keep on pulsing and stirring the oil and lye mixture until both of them emulsify. To test if they have reached the “trace”, dip a rubber spatula and hold it above the pitcher. Let the soap mixture dribble back in. If the soap mix sits on top of the mixture for few seconds, it means the soap mixture has reached the trace.

Quickly add the essential oils and colors before the mixture becomes too thick. If you’re using the cold-process method, this is the point at which you can pour the mix into your soap molds and begin the curing time. For hot process, keep on reading through the “Cooking the soap” section below.

To see what tracing looks like in action, check out the video below (the 4-minute mark).

• Popular essential oils added to natural soap are chamomile, lavender, cinnamon, and vanilla oil. However, the options here are endless. Adding less commonly used oils like myrrh and frankincense can lead to phenomenal scents.

• You may also add a few drops of natural food coloring for vibrant or subtle colors or utilize other natural colorant powders (turmeric, anatto, Alkanet, spirulina, etc.). For hot process soap, you can separate batches, add colors, and combine/lightly blend for beautiful multi-colored soap bars.

• Grains like oatmeal and wheat germ add texture to the soap. Be adventurous and mix different combinations to make your own unique natural soap!

Cooking the Soap

After the saponification process is complete (this is when trace is reached), we can move on to cooking the soap. This step involves heating the soap mixture, waiting a few minutes, stirring, and repeating this until it’s a much thicker consistency.

To see this in action, see the above video from Elly’s Everyday Soapmaking. The crock pot will be our cooking vessel for this process.

To begin, We will turn the crock pot on high and cover it with a lid. If this is your first time, you can start with the low setting, but it will take longer for the mixture to thicken. It is important to monitor the soap mixture closely during the cooking process to ensure that it does not overheat or burn.

During the cooking process, the soap mixture will go through a phase known as the gel phase. This is when the soap mixture becomes translucent and begins to thicken. The gel phase can take anywhere from 30 minutes to several hours, depending on the recipe and the size of the batch.

Once the soap mixture has gone through the gel phase, we need to stir it thoroughly to ensure that it has a gel-like appearance throughout. We can check the soap’s readiness by performing the zap test. This involves touching a small amount of the soap mixture to our tongue. If it zaps or tingles, the soap is not fully cooked and needs more time to cook, usually just 10 minutes or so. But again, ensuring it’s gelled throughout will ensure it’s cooked completely.

Once the soap has fully reached the gel phase, we can turn off the crock pot and remove the soap mixture from the heat. We can then add any additional ingredients, such as essential oils or herbs, and stir them in thoroughly. The soap can then be poured into molds and left to cool and harden.

To make your hot process soap batter pourable, consider adding the following ingredients:

• Sugar, Honey, Agave, or Maple Syrup: 1 tsp. per pound of oil works best. It can be added to the lye and water mixture or at the end.
• Sodium Lactate: 1 tsp. per pound of oil works best. It can be added to the water and lye mixture or at the end.

Cooking the soap mixture is the defining step of the hot process method of making natural soap. By using a crock pot and monitoring the soap mixture closely, we can ensure that our soap is fully cooked and ready to use. The gel phase and zap test are important indicators of the soap’s readiness, and we should always be careful not to overheat or burn the soap mixture.

Curing Your Soap

Now, the most difficult part of the soapmaking process is over, Congratulations!

Since your soap mixture is now poured into the mold, you must cover whatever molds you use with parchment paper or plastic wrap. Store them in a cool, dry location. Allow the soap to cure for at least 24 hours to 1 week.

• Hot process soap can be used as soon as it cures, but if the soap is allowed to cure for a bit longer, you’ll experience more favorable results.
• Just go ahead and cut your soap into your desired bar size once it’s finished curing, and it will be ready to use. Your soap should be cool and hard when the curing process is over.
• If you use individual molds, no cutting is necessary!

Clean Up

Once your soap is sealed in your molds, immediately begin cleaning up your work area since you were working with lye. I’d also recommend not using your soapmaking equipment for anything else besides making soap.

• If you spill any Lye, rinse with plain water, then finish cleaning by neutralizing it with vinegar safely. Keep in mind, though, that there may be a noticeable exothermic reaction with the vinegar if you have enough lye left over on the cleaning surface; that’s normal.
• For any residual lye/oil mix, just leave it to sit for a few days because it will become soap eventually and will then be able to be safely cleaned.

Once clean-up is complete, you’re all finished. Now, you can go teach your friends and family members how to make exquisite soaps, too!

Storage

When you store your ready-to-use soap, it’s best to store it in a paper towel or some other paper-like material so that it doesn’t absorb dust or dirt but still has air exposure. Since hand-made soap creates its own glycerin, that means it will pull in moisture from the air. Just be sure to keep it wrapped or in an airtight container.

Your homemade natural soap is worth all the effort and time. Each and every bar will be the result of your expertise, creativity, and enjoyment.

Soapmaking: Natural Ingredients, Complete Customization

Stop using those commercial soaps and make your own natural soaps instead.

There’s simply no reason to use commercial soaps that leave your skill unhealthy from all the unnatural ingredients and chemicals. With homemade soaps, the chemical reaction from the Lye results in no remaining harmful chemicals.

Creating your natural, hot process soap offers so many wonderful benefits and options. Isn’t it amazing that you can customize your soap according to your own personal preferences?

• You control what ingredients go in there, what fragrances it has, and even what colors and textures you want to achieve.
• By choosing your own natural ingredients, you not only exclude potentially harmful substances you control the quality and wholesomeness of what you’re putting on your skin.
• It’s a fun and rewarding process knowing that you’ve made something special and unique with your own hands. Keep experimenting, keep learning, and enjoy the art of hot process soapmaking!

As you learn more about the art of making soap, you can even gift them to your family and friends or sell them locally. With natural soaps, there are no more nasty chemicals, just all-natural ingredients that are safe and healthy!

FAQs: Hot Process Soap

1.) How to make hot process soap pourable?

To make hot process soap more pourable, try adding a bit more liquid than the recipe calls for at the stage where you’re combining the oils and lye. You can also whip the soap for a bit longer to add some air into the mixture, making it lighter and more pourable. Lastly, there are two additional ingredients you can add for a more fluid consistency:

• Sugar, Honey, Agave, or Maple Syrup: 1 tsp. per pound of oil works best
• Sodium Lactate: 1 tsp. per pound of oil works best

Both of the above ingredients will lead to a more fluid soap batter, more easily allowing for swirling techniques and more advanced designs.

2.) How to make hot process soap smooth?

The key to smooth hot process soap is the mold preparation and stirring technique. Make sure to stir your soap mixture consistently and thoroughly, breaking down any lumps. You can also use a stick blender to ensure smoothness.

Additionally, ensure your soap mold is clean and coated lightly with a non-stick agent, such as olive oil or silicone spray. Also, see the answer to the above question.

3.) Can I use different essential oils for scent in my hot processes soap?

Yes, you can! Essential oils are a great way to add natural fragrance to your soap. Just be sure to add them at the end of the process, after you’ve added the lye, to prevent them from evaporating during cooking. For cold process soap, they can be added at the trace stage before curing.

4.) What safety precautions should I take while making hot process soap?

Wear protective clothing, including gloves and eyewear. Always use a ventilation system or work in an area with good airflow, as lye can emit harmful fumes. Be careful when handling the soap batter, as it can get very hot. Avoid direct skin contact with raw soap batter, especially while it contains undiluted lye water.

5.) How long should I cure hot process soap?

While hot process soap can technically be used immediately after it has cooled and hardened, it’s often beneficial to let it cure for 1-2 weeks. This allows excess water to evaporate, making the soap harder and longer-lasting.

6.) Why is my hot process soap crumbly?

Crumbly soap often occurs when too much lye is used. It could also mean that the soap got too hot during processing, causing it to volcano or heave and result in a crumbly texture.

Ensure you’re following the recipe’s lye recommendations, and keep your slow cooker temperature on low or medium if you’re new to the process. Also, feel free to use more oil in your next batch for a better result.

7.) Can I add exfoliants like oatmeal to hot process soap?

Absolutely! You can add a variety of exfoliants to your hot process soap for a deeper clean. However, remember to add such ingredients at the end of the cooking process, just before you pour the soap into the mold, to prevent them from becoming too soft or discolored.

8.) Why do I need to measure ingredients precisely when making hot process soap?

Precision is key when making soap. Too much lye can result in a harsh, caustic soap, while too little can result in a soft soap that may not lather well. In addition, imprecise measurements can affect the texture and hardness of your soap. So, always measure your ingredients as accurately as possible to ensure a quality product.

9.) What options do I have for coloring my hot process soap?

There are many ways to naturally color your soap. Some options include clays, spices, and infused oils. However, keep in mind that natural colorants might not always produce as vibrant a color as synthetic counterparts. Always add colorants at trace to ensure vibrant color and even distribution.

10.) Why does my soap have a white powdery substance on it after unmolding and curing?

That white substance is likely soda ash, a harmless byproduct of the saponification process. Soda ash occurs when the soap is exposed to air during curing. While it does not affect the soap’s cleaning abilities, it can be aesthetically unpleasing.

To prevent it, simply spray the top of the soap with alcohol immediately after pouring it into the mold and cover it with plastic wrap.