Cold Process vs. Hot Process Soap: What’s the Difference?

Cold Process vs. Hot Process Soap: What’s the Difference?

It might seem random, but have you ever wondered about how soap is made? We know that might be a weird thing to wonder about, but the process is pretty interesting. There are actually a few different ways that you can make soap. Everyone loves a quality soap, especially soap bars. They come in tons of delicious scents and colors, and they feel so luxurious on your body. Soap bars are almost like giving yourself a little massage while also getting squeaky clean! 

When we talk about the soap-making process, we are specifically talking about soap bars. Hand soap and liquid soap, along with body wash, are made in entirely separate processes. If you love soap bars, you might be interested in knowing exactly how the bars are made. The two most common processes for soap-making are the cold process and the hot process

The main difference between the two processes is that the cold process heats soap from the inside out, while the hot process heats soap from the outside in. Both processes use oils and lye to make the soap, but the cold process separates the oils and lye in different containers before combining with an immersion stick. The hot process is done in a slow cooker to heat the soap and combine the oil and lye.  

Pros of Cold Process 

As with everything in life, there are both pros and cons for each type of soap-making process. There are a few pros of using the cold process. One of these pros is that you can customize every ingredient you use, depending on your needs and preferences. Who doesn’t like to make things personal? 

You can also use fresh ingredients when you use the cold process. These can include items like milk or produce purees. Perfect for a fresh and delicious-smelling soap bar! Another pro is that you can customize the design better due to something called the trace. A thick trace can create effects such as whipped cream, while a small trace can create swirls in the soap bar. 

Your technique options are endless, and therefore your design options are limitless. This means that if you want a more unique and creative soap bar, then the cold process is the way to go. In most cases, cold process soap allows for more natural ingredients and fewer additives or chemicals. This is one of the main reasons why people choose the cold process over other manufacturing techniques. If you prefer all-natural products, you will likely want to choose a cold process soap. 

Cons of Cold Process

The biggest con of the cold process is that you have to use sodium hydroxide lye. This chemical can be dangerous if you don’t know how to use it properly. However, during the soap making process, the lye and oils undergo a chemical reaction, called saponification, which turn these materials into soap. So, in reality, this isn’t actually a con—it’s a necessary component of the process that leads to some really great soap. The other biggest con for cold process soap is the timeframe from start to finish. 

Soap made with the cold process takes four to six weeks to cure. That is a long time to wait on your soap. Some people don’t want to wait that long, but the soap will last longer if you let it sit for the proper amount of time. Another con is that a few different colors tend to change due to the high pH levels of cold process soap. If your soap is super colorful, the cold process might not work for you. 

Similarly, some fragrances are highly reactive with high pH levels. This is especially true for vanilla fragrances, which can sometimes turn the soap brown. If you want your soap to be sparkly and glittery, then the cold process might not work. The soap batter is opaque, which doesn’t allow the glitter to show through. And finally, there is a longer cleanup time for the cold process because you have to use individual containers for each color. 

Pros of Hot Process 

Just as with the cold process, there are also pros and cons for the hot process. One pro is that you can customize all of your ingredients, including the oils. Another pro (maybe the biggest one) is that the heating process speeds everything up so much, you can cut and use your soap after just 24 hours. Seriously, talk about a time saver! 

Another pro (depending on your style) is that hot process soap looks more rustic than cold process soap. Hot process soaps have lots of texture, like bumps and roughness. For many people, a pro is you can make soap using the hot process in a crockpot. If you are making your own soap, this makes things super easy and convenient for you. 

For those who hate cleaning (AKA everyone), then hot process soap is for you. It’s so much easier to clean up because it all goes in your crockpot. All you have to do is clean out the crockpot when you finish, rather than wiping down tons of individual molds and containers. 

Cons of Hot Process 

One of the biggest cons of the hot process has to do with your design options (besides the fact that you’re using lye for this process, as well, which we just established isn’t really a con anyway). The soap’s texture is very thick, which makes intricate designs much more tricky. The hardest techniques to achieve are swirls and layering: two of the most basic soap design elements. For those who want a bunch of design elements in their soap, the hot process is not ideal.  

Another con has to do with the fragrances used. Since you are cooking the soap at a higher temperature, the fragrance can burn off in many cases. This means that the fragrance will be barely noticeable after the soap is cut, and it will fade entirely after only a few uses. This is not ideal when you want your soap to leave you smelling crisp and cool! 

Another con? You have to watch your soap like a hawk if you are using the hot process. Even though you just place everything into a crockpot, the soap expands while it cooks. This means there is a possibility of it overflowing, which is why you have to keep a constant eye on things. Lastly, another con is that you can’t use fresh ingredients in the soap because the hot process might burn these fresh elements while they are cooking. 

Where Can I Find Cold Process Soap? 

While all soap-making methods produce great soap bars when done right, many people prefer the cold process. If you are looking for high-quality soap bars that are made using the cold process, check out Bubbly Belle! We have the best variety of soap bars that are made with all-natural ingredients. High-quality and all-natural? Talk about a win-win! 

If you don’t know which scent to try first, then we have the perfect recommendation for you. Our oatmeal and honey body bar is so moisturizing (for real, your skin will feel like a baby after using it) and nourishing. It has a sweet and neutral scent that won’t irritate the skin or give you a headache. Trust us; you’ll be smelling your skin all day long after using it. 

Oatmeal and honey not your thing? Check out our entire collection of body bars. We have everything from lavender to coffee to grapefruit. Whatever scents you like, we definitely have a body bar for you! Even if you prefer a minimal scent, we have neutral-smelling bars as well. Do yourself a favor and stock up on a few different scents. You’re going to love them all! 

A Clean Conclusion

By now, you know that the main difference between cold process and hot process soap is how they are heated and how the ingredients are combined. It’s a matter of heating the soap from the outside in and from the inside out. Both processes can result in a fantastic soap bar if they are made properly. That being said, a lot of people prefer the cold process when it comes to making soap. This is mostly because this soap can include more natural ingredients. 

There are many pros and cons for both processes, so it really is a personal preference if you are making the soap yourself. In terms of which soap is “better,” the process shouldn’t affect the quality of the soap if it’s done properly. 

Ready to get some soap bars and see what all the fuss is about? Check out all of our options at Bubbly Belle. While you’re there, don’t forget to check out our other products, like bath bombs and essential oils, too! 


A Comparison: Hot Process Soap vs Cold Process | Rustic Wise

What Method of Soapmaking is Right for You? | Modern Soapmaking

How to Make Soap from Scratch | Healthline    

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