Basic Cold Process Soap

When I first discovered that I could make soap at home I was amazed! Let me just say; it’s fun AND addicting! A good place to start is with the Basic Cold Process soap method.

What is soap?

In short making soap is a process where you combine oils and butters with a strong alkali to create a reaction (called saponification) that changes the oils into a new saponified version that has special cleaning power. The alkali used is lye, aka; sodium hydroxide for hard soap and potassium hydroxide for liquid soap. Soap is now the water-soluble salt of a fatty acid. This is the way soap has been for centuries but you must realize a lot of what you see commercially is actual not this type of soap anymore. I have been making my own for years and really enjoy the fact I know & choose exactly what I have put into each soap recipe. The combinations are endless!

How Soap Came to be:

Making soap has been around for thousands of years. There is an existing Roman legend that explains the name. Animals were sacrificed on Mount Sapo, where the rain would wash the fat from the animals over the alkaline wood ashes into the river. The people washing clothes in the river found it beneficial to clean clothes.

Science! Who knew?!:

Perhaps if I had seen that amazing reaction in my high school chemistry class I would have paid more attention, and at times now, I wish I had a degree in chemistry! I do warn you though, once you try making soap, it has a way of hooking you and you become a “soap addict”!

As I said, there is a strong alkali involved! LYE! Do be careful and respectful of it! Lye can cause skin burns and also damage surfaces. The whole idea is to have the lye completely react with the oils, and if anything, let there be “extra” fats/oils after the reaction is done, rather than extra lye. That “extra” oil is called super fatting. That fat will be similar to applying a lotion, and also depends on the type of oil or fat. Each type of oil/fat has  certain qualities for skin and soap. See here and here.

Formulating the Soap Recipe:

Now, don’t be afraid if this is sounding very complicated. You DON’T need to be a chemical engineer at all. There are aids to calculating how much of each of the oil you would like to use to give you a good quality soap along with the lye calculator. I always use this recipe calculator. It lets me fill in the amounts by either percentage or weight, and how much super-fatting I’d like to make a bar of soap to my needs and personal preference. It will then give you the rating of the recipe in various categories. Like I said, I’m not an engineer. I try small batches when I have concocted an acceptable recipe and I also test my soap by doing lots of hand washing. The best recipes are usually a combination of hard fats and soft/liquid oils to the lye that is dissolved in some water based liquid.

Basic Cold Process Soap - soapcalc

Here is a basic laundry bar recipe. You quickly will learn that coconut oil in soap makes it very bubbly and also very cleansing. For that reason I have it at 50% of the fats, since I want this to be for cleansing. The other fat is the beef tallow. (which you can render yourself as in my tutorial)

Safety First!

For safety, you need protective equipment (safety gear): Rubber gloves, eye protection (safety goggles), long sleeves in case of splashes, apron etc. The lye should not come into contact with any skin as it will burn it. If it does make sure to rinse with cold water immediately.

The Tools:

All the ingredients are measured by weight, so you need a good digital scale, candy thermometer, stirring utensils, bowls and vessels for measuring/mixing. An immersion blender makes the mixing effortless.

Basic Cold Process Soap - tools

DO NOT use anything that is aluminum, as it will react with the lye! I have used pyrex containers for years with no issue but have been informed that sometimes a shock of temperature can make them break. If you are concerned please use something like a heat-resistant plastic or stainless steel. (do not use tin or aluminum)

The Basic Soap Recipe: (makes a basic laundry cleansing bar)

  • 12 ounces coconut oil
  • 12 ounces beef tallow
  • 8.4 ounces of water (weighed)
  • 3.9 ounces lye
  • fragrance or essential oil of choice (I added a bit of Limonene)

Basic Cold Process Soap - tallow coconut oil

Step #1:

First, gather all your ingredients. Once the lye is added slowly to the water the reaction will heat it up and create some fumes. If you can not have good ventilation use a fan hood to avoid breathing these fumes. I use a container of ice to keep the lye solution cool.

Step #2:

Measuring is in 2 parts. One is all the oils/butters/fats, measured and liquefied, and the other is the lye dissolved in the water (sometimes lye is dissolved in milk or tea). See my other recipes for using milk as the the liquid. It’s a good idea to start with a simple soap recipe to get the hang of the process.

Basic Cold Process Soap - melting oils

The temperatures are somewhat important. It is best if the oils and the lye water are roughly about the same. The lye here is around 100 degrees.

Basic Cold Process Soap - keeping lye water cool

6Basic Cold Process Soap - pouring lye into water cool

The oils need some heat to melt the tallow and coconut oil. Short bursts in the microwave will melt the tallow and coconut oil. To save on cleaning I add each fat/oil to the same bowl and reset scale to zero in between measurements.

Basic Cold Process Soap - melting fats/oils

Step #3:

Once both the oil/fat combination and lye solution are ready, I need my stick blender. I pour the lye water into the oils carefully, and start to stir (silicone spatulas work great for this). This is where the magic starts…

combining using stick blender

The reaction is starting to take place, but will depend on the ingredients. This particular combination has a reaction that is pretty quick. You will see it thicken and emulsify with the use of the stick blender. Try not to introduce too much air into the mix.

Basic Cold Process Soap - reaching trace

Once you see it starting to resemble pudding, it is what the soapers call “trace”. Trace is when it leaves a trail in the mixture. I make sure I have to mold ready when I start as I don’t want to be caught off guard. Depending on certain factors, it may get thick too quickly and make difficult to get into a mold(s) easily.

Basic Cold Process Soap - mold prep

Step #4:

I like to stir for a bit to rid it of air bubbles, and incorporate the fragrance or essential oils. Then pour soap into the mold. I use a cheap plastic container as a mold that has some flexibility and simple sides. Pretty well any form can be used as a mold (avoid aluminum)I line it with parchment paper (or freezer paper) to make removing very easy. There are many options for soap molds, wooden and silicone molds work well.

Basic Cold Process Soap - pouring into mold

Before poring the soap mixture into the mold make sure there are no oils separated from the mix. As it gets thicker (the oils reacting with the lye and starting to cure), you can have fun sculpting the tops like icing on a cake. NO LICKING THOUGH!!! This recipe is a going to be a laundry bar, but when using other recipes you can colour portions of the mix to swirl and make designs etc. Soap makers can be quite creative in their designs.

Basic Cold Process Soap - swirling tops

Basic Cold Process Soap - clean up

Step #5:

Clean up is the worst part, I’ll admit. You definitely want to keep gloves on! I like to get all the goop off everything as much as possible via paper towels that go to trash. Then the amount of greasiness for washing and drains is lessened. You can also wipe with some rags and leave them to finish the reaction as then they will have soap in them.

Basic Cold Process Soap - cutting and demolding

You now have the choice to “insulate” (wrapping in a blanket or such) to let the heat “gel” the soap or prevent heating by popping into fridge. In summer I find it hard to prevent any gelling so I let it gel by covering lightly with a blanket. The soap saponification will heat the soap. This recipe makes a hard bar, so don’t wait too long to cut it. It can be cut once it is hard and sturdy enough, which means it has done it’s chemical reaction.

It’s always exciting to cut, such a large block of waxy, shiny, chemical magic! A knife usually works well but you can also use a wire cutter (like a cheese cutter) Even though the soap has hardened it should still cure. To test to see if the all reaction has happened there is a test called the ‘zap test’. Touch the soap with the tip of your tongue, if you feel a zap then there is still lye that has not been saponified.

When making soaps with other ingredients such as olive oil and luxury oils they can actually become better with age; like wine does. Before you know it you will be wanting to add all kinds of great butters/oils into your soap batter, not to mention all the scents possible. Cocoa butter, rice bran oil, shea butter, avocado oil, lard (makes a lovely bar)… Homemade soaps are also a great way to make gifts.

Check out my Chocoholic’s Milk Soap Recipe and even the Red Wine Hot Process Soap If you need a soap dish (concrete of course) Easy Rock Soap Dish

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  1. I found your website yesterday. I’m going to save much of it for rainy days as the Sun is now making living outside a joy.
    I too have been soaping for a long time and always use SoapCalc to control my new ideas for a recipe.
    One piece of advice: When you’re done soaping, put all the used, wiped off, but not cleaned utensils somewhere safe for two days, then the goo has turned to soap there too (Captain Obvious on board 😉 ), and cleaning off soap is so much easier than cleaning off goo. And for Goodness sake don’t put any of it in the dishwasher unless you want to clean dishwasher, floor and everything near by.

    1. Yes, I have read that! I always intend to do that but can’t seem to find a place to stash since I use my kitchen. I do use old towels to wipe and let them cure. I have heard about horror stories of clogged pipes. Wow, snow? we had a long winter here and for some reason our summer is crazy cold today. Winter is for the dyeing and sewing and whatever else comes to my mind.

    1. I would make the popular recipe that includes borax, soap and washing soda. It works well, just don’t use super-fatted soaps. I’m sure there are many of that recipe on the net.

    1. It is 12 ounces. But if you want to ‘concoct’ a recipe with your own choices the ‘Soap Calc’ is the best way to make sure you have a good recipe. This combo will be quite bubbly, clean well and very hard. Happy Soaping!