Making Cold Process Homemade Soap

One of the more unique hobbies I’ve picked up over the years is soap making. I like to know what’s in my soap and I like to experiment with making different kinds of soap. I’ve made chocolate soap, orange citrus soap, spearmint soap, and a few others. My wife and I realized that we were running low on our homemade soap so we decided to make another batch of Sweet Orange Soap.

Items needed to make soap:
Oils (usually at least 3 different kinds)
Kitchen scale to measure out oils and lye
Food grade lye, or sodium hydroxide
Safety equipment, (gloves, eye protection, protective clothing)
Candy thermometer
Water or liquid such as goat’s milk
Soap Mold
Wooden or plastic measuring cups and spoons
Immersion blender
Freezer paper
Old towel or blanket

Soap making isn’t difficult, but it does require precision, and a healthy respect for lye used in the process. Soap is composed of three things, an oil, lye, or its chemical name, sodium hydroxide, and a liquid, usually either water or a milk, like goat’s milk.

The trick is to combine the ingredients in the proper proportions so that all the lye is converted by the oil. A good soap has neither lye, or oil left over. If lye is left after the saponification process, (a fancy word to describe the conversion of lye and oil into soap), the soap can sting when being used. If oil is left over after saponification the soap can go rancid.

oil in a bucket

I use a website to calculate the ratio of oil, lye, and water to use in each batch of soap. I also super fat my recipe. This means I use about 5 – 7% extra fat in my recipes. This isn’t enough to cause the soap to go rancid, but it does ensure the lye is fully converted and that the bar of soap is slightly softer.

So, what kinds of oils do I use in the making of my soap? Can any oil be used and why have different oils at all?

I use a combination of three kinds of oils. Olive oil, coconut oil, and palm oil. The olive oil helps the bar of soap stay soft while the coconut oil helps with the cleansing process. The palm oil is used to help even out the other oils and it helps the soap come quickly to trace. I’ll talk about soap and tracing a bit more down below. For now though, I have found these oils to be a great combination in producing a bar of soap that is comfortable to use, and still cleanses really well. I used this recipe, Citrus Burst Soap – J&K Soap to make this batch of soap.

Soap Making Safety Tip: Lye is a caustic chemical, which means it will produce a chemical burn if it comes in contact with your skin. The lye reacts with moisture and produces heat. Always wear safety gear, including hand and eye protection when working with lye. If you do come in skin contact with lye neutralize it with vinegar. In case of eye contact seek medical attention as soon as possible.

empty soap mold

To start off with we need to make sure we have everything prepared. Once the process starts you’re on a timer. I like to measure out the oils first. Remember to measure by weight not volume.

olive oil in a pyrex measuring cup being weighed

oil in a bucket

After measuring the oil out place it into a pot on the stove under low heat. Some oils are solid at room temperature and need to be heated up to melt them. The goal is to have the oil at a temperature of 110F(43C) to 120F(49C) when the lye is ready.

melting oil

While the oil is slowly heating measure out the lye on your scale and set it aside. Now measure out the liquid you need. As I mentioned above lye reacts with water and produces heat. If only water is used the water may heat up as high as 200F(93C). To combat the high amount of heat that will need to dissipate I often add ice cubes to my water to bring it to the amount I need. This helps cool the reaction.

Soap Making Safety Tip: One really important thing to remember is to always add lye or something that contains lye to something else. The lye is added to the water, and the lye water is added to the oil. This is the safest way to transfer lye as adding a small amount of water to the lye can result in an explosive chemical reaction. (Don’t worry I’ve never had any issues with lye myself)

When working with lye avoid using anything made of aluminum. The lye or lye water will react with the aluminum and cause it to blacken or stain.

Place one candy thermometer into the oil and another thermometer into the lye water. The lye water will need to reduce in temperature to between 110F(43C) to 120F(49C) and the oil will need to be in the same range. The temps can be about 10F(6C) degrees apart, but should be as close as possible when mixing the two. Once the temperature on both lye water and oil hit the desired range pour the oil into your mixing bucket. I use a food grade bucket to mix everything in. Carefully pour the lye water into the oil.

At this point if you have an immersion blender you can use that to stir the mixture. If you don’t have a blender you can use a long wooden or plastic spoon, it just takes longer.

combining ingredients to make soap

How long should the oil and lye water be mixed together? The key thing to look for here is what soap makers call “trace”. The lye water and oil react together and start to thicken up. Once the mixture is thick enough to resemble pudding and leave trails when you move your spoon or blender around then it’s reached trace.

combining ingredients to make soap

In the photo above you can see how ridges will form on the mixture and take awhile to smooth out. This is a good sign of the soap starting to trace.

At this point if you have any additions you’d like to put into the mixture this is the perfect time for it. Since this was a sweet orange soap I added dried zested orange peel and an orange essential oil. It’s important to measure out the essential oil based on the size of the recipe or you can easily end up with not enough or so much that when you use the soap your bathroom will smell like a Florida orange grove.

combining ingredients to make soap

After finishing mixing in my additions it was time to pour the soap into the prepared mold. The mold is lined with freezer paper to make removing the soap out easier after it sets.

bar of homemade soap in mold

The top of the soap may form a white powdery looking layer if left uncovered. I generally place a piece of cardboard over the top of the soap and then wrap it in an old towel or blanket. The soap must sit for a minimum of 24 hours before it can be cut. No peeking while the soap sets.

bar of homemade soap in mold

bar of homemade soap

After a day it’s time to cut the soap. I use a miter box and a dough cutter to slice the soap into small bars.

cutting soap

cutting soap

After cutting the bars up I place them into a cool, dry place. Usually I keep an shoe box around to hold the bars.

.cut bars of homemade soap drying

It takes about three weeks for the soap to dry out enough to use. If you use the soap before then it will be too soft and will quickly dissolve.

After the three weeks the soap can be packaged up for giving away, stored, or used right away. Homemade soap is great for using in the shower, bath, for general hand cleaning at the sink.

I really enjoy using the soap myself. What most people may not realize is that a lot of “bar soaps” in the store are really detergent bars. The glycerin that is formed during the soap making process is worth more than the soap itself and is separated out by companies and sold.

Homemade soap not only cleanses it helps hydrate your skin to keep it moisturized and refreshed feeling.

Enjoy feeling clean!

– Jason Snell