Cold process is probably the soap maker’s favorite process for handmade soaps. It is very versatile, allowing to create textures, shapes, designs with different colors. The soap product you get is professional grade. And you are in full and complete control of the ingredients you use. In this post, you will find all you need to know about cold process and a list of free cold process soap recipes tested and tried in this blog:
- Herbal Soap Recipes
- Design Soap Recipes
- Food/Spices Soap Recipes
- Castile Soap Recipes
- Beginners 1-Oil Soap Recipes
What is Cold Process Afterall?
Handmade soap is produced by mixing a mixture of oils with lye water. And that’s it!! No other fancy chemicals with weird names! Surprising, isn’t it?
OILS + LYE (CAUSTIC SODA) -> SOAP SALT + GLYCERINE = SOAP
Cold process is based on this principle, where soap is made with no heat source during saponification, using room temperatures, and the heat released by the chemical reaction itself. The temperature at which the oils and lye water are mixed together needs to be controlled to ensure the produced soap has no issues. However, the only heating necessary is the one to melt solid oils.
Cold process soap creates hard soap bars, whose properties are mostly given by the oils used in the mixture: conditioning, foamy, bubbly, cleansing, mild.
Please, explain about “Trace”…
Terms such as “trace” are always mentioned when speaking about cold process. “Trace” means that all the oils have been emulsified with the lye water – however, saponification is only starting now. You can tell by the way the batter leaves “traces” when, for example, you let drops fall on its surface, pretty much as in liquid pudding. With experience, it will be easier to recognize the difference between having oils and lye, or soap at “trace”: you no longer see oils floating but an emulsion with a slightly different scent.
… And “Gel Phase”? …
“Gel phase” happens afterwards “trace”, when the soap batter has been poured into molds and saponification continues. The saponification reaction releases heat, and when this heat is high enough, we say that the soap reached “gel phase” – soap looks brilliant, gelatinous, like gel.
Reaching “gel phase” makes the soap less opaque and with brighter colors, therefore, many soapmakers make sure the “gel phase” takes place by properly insulating thermally the mold containing the soap.
This coconut lavender soap has gone through gel phase – the middle looks darker and somehow less opaque. I didn’t do it on purpose: it was a hot summer day and the room temperature was near 30ºC – 86ºF. The soap turned out quite good.
… And “Soda Ash”? What Is It? How to avoid it?
Soda ash is a white powder that forms on the surface of soap, it looks a bit like white ash powder. It is the product of unsaponified lye reacting with carbon dioxide present in the air, during the saponification. The powder is completely harmless, but may be a nuissance for your pretty colors and designs.
Using less water (water discount, or a bigger lye concentration), gel phase (you need to thermically isolate your soap mold) and less liquid oils are means to avoid soda ash. Other ways to avoid it: sprinkle your soap with alcohol or leave your soap in soap molds for a few days after the soap solidifies.
In all the recipes I found and wanted to try, I always tried to use only natural or minimally processed ingredients, so you won’t find artificial colors or weird addictives here.
Even the idea of adding dyes or herbs is just to make the soap more decorative, more pleasant to the eye. Essential oils add aroma, but they may also provide some medicinal properties: vitamin, anti-oxidant, anti-inflammatory, anti-fungal, anti-bacterial, moisturizing, smoothing, etc.
In the end they are all optional ingredients. The base ingredients are oils and lye (sodium hydroxide for soap bars).
So let’s go to the ingredients:
Base Ingredients: water, sodium hydroxide (lye), oils
Sodium hydroxide: 100% pure caustic soda / lye /sodium hydroxide, in grain or small spheres, do not use drain pipe cleaners without checking ingredients list, as they may contain other substances.
Water: preferably distilled or relatively demineralized. If you have a tumble dryer or a dehumidifier, use the water in the tank after filtrating it with a muslin tissue or cheesecloth (to clean dust and laundry fibers).
Oils and butters
I mainly use vegetable oils, having only done experiments also with lard. I advise you to buy deodorized or refined products, so that you have a more neutral product in terms of color or scent, but you can use the more natural products, having in mind the oil or butter will influence the scent in the final soap.
Essential Oils (optional)
I only use essential oils as soap fragrance, making an exception for some fragrances whose respective essential oils are extremely expensive (for example, absolut rose or jasmine).
To get started you can buy a starter kit with some of the most common essential oils from one of these brands:
Please, make sure to also purchase May Chang essential oil, to fix/keep the citrus essential oils scent.
Personally, I have been buying almost every essential oils at Plena Natura, because they are cheap and they give a great deal of trust by presenting good information online on all their products. In Portugal, Pranarom essential oils are also an option.
Recently, I’ve reviewed other essential oils suppliers. It didn’t make me change from Plena Natura for now, but it gave me a good insight of how much in the dark we actually are about these products.
Essential Oils or Fragrance Oils?
I am no longer an essential oils “fundamentalist” as I believe that cheap essential oils (there are numerous at Amazon or Ebay) are worse than some good quality fragrances, and we honestly don’t know what manufacturers actually put in these so-called essential oils (see Where Do You Buy Essential Oils For Soap Making? to know more).
My advice, whether you prefer to purchase an essential oil, a natural fragrance, or a “normal” fragrance, is to get information on their ingredients and see if there are substances there that raise concerns for you (such as allergens, see Commercial Soap Ingredients – What Are They?). Know what you are buying.
Be ware that there’s no fragrance or essential oil without any sort of allergens like geraniol, linalool, limonene, to mention only a few. I personally have never developed an allergic reaction to any of them, so they are not harmful per se.
It is possible to use only one essential oil or a mixture of some, they give a very pleasant aroma to the soaps and may even add some medicinal properties.
Or you can mix essential oils with fragrance oils. Some of the best perfumes are a blend of essential oils and synthetic fragrances. I particularly like the Rose one, to mix with geranium rose essential oil and patchouli.
I use only natural dyes. Many of these products can be found in the kitchen: cinnamon, sweet pepper, paprika, turmeric, spinach, carrot, pumpkin …
To better control colors, or to obtain tones less common in nature, I also use micas, which are considered natural dyes, despite being minerals.
Cosmetic clays are my favorite way to color soap. Not only they are natural ingredients, gentle cleansers for your skin, they are also reliable and stable about the soap color, and scent “fixers” (meaning they help to sustain essential oils scent in soap). They are a total winner ingredient.
Here are the ones I use the most:
Extracts and Anti-oxidants
These are natural anti-oxidant extracts to prolong the life of the soap (to not become rancid). The most used are:
Herbs and Flowers (optional)
They are only for decoration or exfoliation purposes, as their herbal properties usually do not survive saponification, and must always be added dried, in puree, or ground into powder. Something I learned from my experience was not to use large pieces of fresh herbs and flowers: they become brown, rotten and ugly (ugh!).
Many flower petals, even when dried, turn brown and make the soap look… unpleasant. Having “pieces of soft matter” coming out of the soap and falling into the bathtub during the bath may also not be desirable for many. So, you actually can skip completely adding herbs, it’s totally a matter of personal taste.
If you don’t have the possibility of growing and drying your own herbs, you can purchase dry herbs here.
Cold process soap includes lye in its list of ingredients. It’s probably the main cause that many people shies away from making soap at home. While lye is corrosive and does need caution, you don’t need a biohazard suit or any special gear to make soap safely:
Cold Process Soap Recipes
Simple recipes based in herbal or floral ingredients: herbal infused oils, floral essential oils, exfoliating herbs…
Soap with layers and simple designs. I have to be honest I don’t have pacience for a load of intricate and complicated designs with lots of steps. I do deeply admire the work of the soap makers that do.
Food/Spices Soap Recipes
Fun soap colored with kitchen ingredients you also eat: carrots, cinammon, turmeric, milk, honey, beer….
Castile Soap Recipes
Olive oil is my favorite soap of all. Probably because I am mediterranean, and love olive oil: it’s also quite common and inespensive in Portugal. Probably because the soap is really awesome and very easy to make. Most likely because all of this. Fact is you will find a lot of 100% olive oil soap, or castile soap recipes at Herbalcochete.
Beginners Recipes – 1-Oil Soap Recipe
Another thing I love: simplicity. One-oil soap recipes are hard to find. Most likely because it’s much easier to make a good soap with a mixture of oils than one alone. But I love the idea of using only one oil, lye and water to make soap. Therefore, you will find a lot of one-oil soap recipes at Herbalcochete. You can then pick up the recipe with your locally available oil and make great, cheap soap!!