What is Cold Process Soap?
All soap is the result of a chemical reaction called saponification that occurs between lye and fat or oil. This process creates glycerin, soap, and unsaponifiable which gives handcrafted soaps their unique qualities.
Cold process soap making is a soap-making method that combines oil and an alkali (also known as sodium hydroxide or lye) to make soap without additional or external heat sources. This process of converting the fats or oil into soap (thru the introduction of lye) is call saponification.
Most cold-process soaps also require a longer waiting period of 6 – 8 weeks, some even longer, before they are ready for use, which in soap makers terms is call “curing time”.
Unlike hot processed soap which tends to look more rustic, soaps made through the cold process method tends to look smoother and polished aesthetically.
What does the term cold process refer to?
Understanding what is in your soap helps reduce your daily exposure to toxins and synthetic chemicals that could be detrimental to your health.
There are generally four basic methods of making soap, cold process, hot process, using melt and pour soap bases, and rebatching.
Like the branches extending from a tree, there are also hybrid processing methods like CPOP (Cold Process Oven Process), HPOP (Hot Process Oven Process) and CPHP (Crock Pot Hot Process). These are essentially a mixture of processing methods where heat is applied to speed up saponification. We will leave these for discussion in the future.
Cold process soap making, often referred to as cold process for short or simply “CP”, is a method of soap making that uses a combination of oil and lye to make soap without additional or external heat sources.
The hot process soap-making method uses external heat sources such as pots, kettles, and heating chambers, to accelerate the saponification process. Traditionally, soaps (e.g. Aleppo, Castile, Marseille, and others) are made using the hot processing method, also known as soap boiling. Modern soap e.g. Dr. Bronner’s Castile liquid soap is made using the hot processing method.
The melt and pour soap-making method uses ready-made lye-based soap bases. These soap bases are hot processed during production using the same saponification process involving mixing oils/fats and an alkali (such as lye). As an end product soap base user, you simply heat and melt the soap base, pour it into a mold, and allow it to set. It’s ready to use after it cools and hardens.
In cold process soap making, a soap maker intentionally lowers the temperature of the caustic solution so that the saponification process/reaction rate is lowered allowing cold process soap makers to create swirls and other patterns, without the fear of rapid saponification or solidification due to temperature cooling.
Soap makers are also known to promote the cold process method as a better soaping method for the preservation of plant-derived oils and butter benefits.
Most synthetic detergent-based cleansers in the market, such as dish soap, liquid hand soaps, and shampoos are so good at removing oils that they tend to strip your skin of its natural oils and could leave your skin dry and itchy.
On the other hand, lye-based soap is better for your skin as it contains unsaponifiables and residual glycerin that arises from the saponification process.
Unsaponifiables serve as an excellent occlusive while glycerin is an excellent emollient that softens and moisturizes your skin by attracting moisture into your skin.
Due to the simplicity and flexibility of cold processing, the cold process method is now the most common soap-making method utilized by most modern homemade soap makers.
Cold process vs hot process soap making?
Traditionally, all soap is made using the hot process method. With the discovery of cold processing, many home and small-batch soap makers have been won over by its simplicity and ease of learning.
So which method is best for soap making?
Both cold process and hot process soap making methods use lye to create saponification and utilities the exothermic heat created by the saponification reaction that occurs between fats or oils and your alkali (lye).
Both cold and hot processed soap allows you to choose your oils, scents, colors, additives and can be made with a super-fat (or lye discount). Because of the super-fat, soap is milder and less aggressive on your skin. The skin will retain its hydrolipidic film after having been washed, which gives it extra hydration and protection.
Hot processing soap differs from cold process soap making with the addition of applying an external heat source (e.g. crockpot) to speed up the saponification process while cold process soap uses only its own exothermic heat from the saponification process (with the introduction of lye to fixed oils).
So which process is better?
There are two schools of soap makers and both are in love with their own method. It has always been a debate when the two schools of thought meet to discuss their beloved soap-making technic.
At Singapore Soap, we love and enjoy making soap using all three methods. We will list the pros and cons of using the cold and hot process soap-making methods for you to decide on your own.
Pros of Cold Process Soap Making
Ease of creating beautiful swirls and patterns
Due to the incomplete or slower saponification process, your soap batter is still fluid when it reaches trace and much easier, than hot processing, for designs and layering.
Less hands-on time
Essentially, all you need to do is introduce lye to your oil, mix to trace, pour into a soap mold and wait for about 4 to 6 weeks for the saponification process to complete by itself. The actual hands-on time use is short.
Cons of Cold Process Soap Making
Longer wait time
The cold process, without external heat to speed up the process, takes much longer for the saponification process to complete. It will take about 4-6 weeks (or more for some soap recipes) for curing to complete. This means that the soap can’t be used until saponification is complete (lye has fully been neutralized).
More space needed
You need more space to store your cold process soaps while they cure. As they are still caustic while curing, you need to keep them away from children and pets for safety reasons. Therefore, you’ll need to plan on a dedicated spot for your soaps’ curing process until they are ready for use.
Pros of Hot Process Soap Making
Shorter wait time
Soaps made using a hot process have a shorter curing time. The additional heat source applied speeds up the saponification process. Hot process soap can be cut within one day and used right away. While generally safe to use right away, an additional one week of curing may be preferred.
Less space needed
As hot process soap is fully ‘cooked’ i.e. saponification process has completed in the pot before pouring into molds and has a shorter curing time, you do not need as much space to store your hot process soaps while they cure.
Cons of Hot Process Soap Making
Rustic or thicker texture
As saponification has been completed in the pot for the hot process, your soap batter may be thicker and less fluid than cold processing. Soap makers either love it or hate it. A thicker texture is great when you wish to add heavier additives but more difficult to achieve a smooth creamy appearance, laying or swirls without using additive.
More hands-on time
Hot processing soap making requires more hands-on time while you ensure cooking is done properly. It’s an advanced method of soap making that requires an understanding of the temperature to use, monitoring of the cooking process, when saponification is considered complete, and more. A beginner soap maker should get a deeper understanding of cold processing before attempting the hot process method for your soap.
Is Cold Process Soap Good for Skin?
Is cold process soap good for your skin? Is cold process soap better than commercial body wash?
These are just some of the common questions asked on cold process soap vs commercial soap.
Having a deeper understanding of ‘soap’ may help.
Real soap is made by combining fats or oils and an alkali, such as lye, to form soap. This process is called saponification. When made properly, no lye remains in the finished product.
Today there are very few true soaps on the market. Most body cleansers, both liquid and solid, are actually synthetic detergent products.
Synthetic detergent products are mainly made using alkylbenzene sulfonates: a family of soap-like compounds, e.g sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES).
Some of these detergent products are actually marketed as “soap” but are not true soap according to the FDA regulatory definition of the word.
Detergent-based cleanser or ‘soap’ contains SLS and SLES that are known human irritants that can be toxic or harmful to us. (Source here & here)
Real soap and Castile soap on the other hand are NOT human irritants and are NOT toxic or harmful to us. (Source here & here)
Cold process soap is real soap made thru the process of saponification. If made properly, there is no lye remaining and are considered healthier for your skin.
Cold process soaps also contain residual glycerin which is a natural skin moisturizer that helps restore the skin’s moisture balance and protect it.
Handmade cold process soap bars are also commonly enriched with natural ingredients e.g. activated charcoal powder, french green clay, colloidal oatmeal, and natural oils (thru superfatting). These ingredients are known to help with skin problems such as acne, dry skin, sensitivity.
How do I make cold process soap?
Cold process soap is made thru a process called saponification.
Saponification is done by combining your oils and fats with lye (sodium hydroxide or bar soap and potassium hydroxide for liquid soap).
Scientifically, saponification is the process that converts fat, oil, or lipid, into salts of fatty acid (i.e. soap) and glycerin thru the introduction of aqueous alkali (e.g. NaOH or KOH).
When the alkali/lye is introduced to water, exothermic heat is triggered, the temperature of the lye solution could reach up to 100 degrees celsius.
In cold process soap making, this heated lye solution is allowed to cool to around 38 to 40 degrees celsius before being introduced to the fats, oil, or lipid.
In contrast to hot process where an external heat source (e.g. crockpot) is used, this cooling process and not using an external heat source is how cold process soap is made.
Cold process soap are made using only its exothermic heat created during the saponification process.
What is the difference between handmade soap and commercial soap?
Handmade soap e.g. cold process soap is different from commercial soap.
Cold processed soap is soap made from natural plant-based oils and lather is produced naturally once they are converted to soap thru saponification. It is non-toxic and healthier for your skin, especially for sensitive skin.
Commercial soap is cleansers made from synthesized surfactants and detergents. Synthetic surfactants are harsher on your skin and can strip the skin of moisture leaving the skin feeling dry and overly squeaky clean.
When Is Cold Process Safe to Use?
In short, a cold process soap is ready and safe to use after 4 to 6 weeks once curing is completed.
The long answer is the length/period of curing to complete is not uniform and can be subjective though.
Depending on the soap maker’s method, water discount, lye discount, type of oil or fats used etc. Use of more liquid oil vs hard oil would generally require a longer curing period. We will leave it topic for another article.
How Long Does Cold Pressed Soap Last?
In general, a 100 grams cold pressed soap bar will last around 20 to 30 days of showering and are generally best used within 1 year.
Depending on the percentage of hard oil used in the soap recipe, a bar of soap can be made firmer i.e. harder to dissolve, and thus last longer in the shower.
Using a soap dish for the bar of soap to sit and excess water is drained, can also help it to last longer. If left sitting in water, a bar of cold processed soap will turn mushy after some time.
Cold Process Soap Making Supplies
Looking for materials needed for cold process soap making?
Singapore Soap is a one-stop soap making supplies website that can provide for all your cold process soap making supplies needs.
Some of the cold process soap making supplies available for purchase online are:
- Fixed oil e.g. coconut oil, olive oil, castor oil & more
- Butter e.g. shea butter, mango butter, cocoa butter & more
- Waxes e.g yellow beeswax, white beeswax, soy wax & more
- Essential oil e.g. lavender, peppermint, rosemary
- Fragrance oil
- Colorants e.g mica & pigments
- Clay & Powder e.g Green clay, french clay, colloidal oatmeal
- Soap moulds & Cutters
- Herbs & spices
- and many more available at our store
Cold Process Soap Making Recipes
Looking for simple easy to start cold process soap making recipes?
At Singapore Soap, we have some free cold process soap making recipes that you can use to make your own homemade cold process soap.
Locate the free cold process soap making recipes here.
Cold Process Soap Making Classes
At Singapore Soap, our artisan soaps are locally crafted in Singapore with premium quality ingredients sourced around the world and free from toxins. Depending on the soap, uses, and needs, our soap-making technics will apply.
Want to learn how to make your own soap with our soap-making classes in Singapore?
Singapore Soap conducts soap-making workshops for people who are interested to become soap makers. Join our natural handmade cold process soap-making classes today and learn to make your very own cold process soap.
Register for our basic or advanced cold process soap-making classes today and give your family a boost of health with your very own handcrafted, chemical-free, wholly natural handcrafted soap.
