Here you can find a tutorial on how to make your own soap at home. The guide will have sections that you can find just below, so feel free to skip to the part you need, but if you are new to soap making, I recommend reading it from beginning to end.
For soap making you need:
3) Lye – if you are making bar soap you will need sodium hydroxide, if you are making liquid soap then you will need potassium hydroxide.
Simple put, we will combine all the ingredients together (in special order), mix the solution with immersion blender until we reach a trace. A trace means that when you stop mixing and lift the blender stick over the pot, the drips from the blender won’t dissolve in the liquid and instead cling to the surface leaving a trace. You can have a light trace – barley holding on the surface or a heavy trace – like a pudding.
First thing, you don`t need do buy cold – pressed oils for soap making because they will lose their benefits due to the high heat. So go ahead any buy the biggest and cheapest refined oils you can find in supermarkets. The only time I use cold-pressed oil, for example extra virgin olive oil, is when I want the soap to be darker in color.
Second, to have the best shelf life of the soap, up to two years, buy oils that have a year or more to go on their best-by date.
Third, I do not use commonly used palm oil and coconut oil due to vegan and environmental reasons. So, I will give you a few recipes without them. Generally, it is best to use the oils that are common for your region. Living in Mediterranean area, olive oil is my go to choice, but if you are in area where mangos abound, go ahead and use mango butter.
Typically, a recipe will ask for more than two oils, with the exception of olive oil, which can stand alone and is also known as castile soap, which we are going to make here as an easy example.
Different oils contribute to soap in different ways, such as lathering, conditioning, and cleansing, etc. There is also a best percentage of each oil to use and I will put the table below for the soaps I use. For example, olive oil, can be used at 100%, whereas castor oil, which aids in lathering, should be used at roughly 5%, sunflower oil at 15%, and canola (rapeseed) oil at 40%. So, for the oil section of the recipe, you may use 15% sunflower oil, 40% canola oil, 5% castor oil, and 45 percent olive oil.
It’s recommended to use distilled water, but you can use tap water if you boil it first and let it cool before using it; it’s safe, but it may affect your batch:
a) I you have hard water (and Zagreb does), minerals can cause orange spots on your soap due to oxidation of some of the soft oils in your recipe. They can also affect soap lather, cleaning performance and can cause the soda ash on top of your soap.
b) Water contains chemicals that make it drinkable, such as fluoride and chlorine, which may cause color changes in your soap or cause it to go rancid faster.
c) The third issue is that tap water quality varies, so if it works one time, it might not the next, and given the variety of things that can go wrong with soap, determining whether the water was the cause will be difficult.
All this can be visible much later after the curing process and then you will have an expensive mistake if you made a few batches. You have a better chance of success if you have soft water or a filtering system. Then I would advise to use citric acid in the recipe because it can help a lot for preventing scum and stopping the soap for going rancid.
My advice is to look for a store where you can get distilled water in bulk and fill your own bottles to avoid using plastic bottles, or if you’re going to use the same recipe all the time, make a small batch with tap water and see how it goes.
Also, if you’re going to use distilled water in plastic bottles, get the bigger ones (5 liter/1.3 gallons) and when its empty use it for bio-enzym which may be used for cleaning, as a shampoo and other things.
Lye, also known as sodium hydroxide or caustic soda. Because it’s a highly corrosive and harmful ingredient, it’s logical to wonder why I’d want it in my soap? The answer is also the beauty of chemistry; when combined with water and oils the saponification process occurs and it becomes safe to use. The same happens when we combine it with another toxic substance called Chlorine; we get the table salt that we safely consume every day. So, before saponification process, it is important to be cautious while working with lye, not to breathe it, touch it with bear hands and use protective glasses because it might irritate your eyes. This leads us to our second section; safety and equipment.
Safety and equipment
For your safety, always use:
2) Face mask
4) Long sleeves top and bottom
5) Socks and shoes
6) White vinegar – if you spill lye (on the counter, on your skin), clean it up as much as you can with water and then neutralize the spot with vinegar.
7) When mixing the lye into the water, choose a ventilated place, such as an open window, a stove vent, or even better, work outside if possible.
Equipment you are going to need:
1) Rosin paper (plastic cover) for counter protection, or a small compact foldable desk used specifically for that reason.
2) Kitchen scale
3) Immersion blender
4) Silicone mold
5) Thermometer (the laser gun is the best but digital one will be fine as well)
6) Pots and containers:
a) Stainless steel pot or plastic container (2-5) for measuring lye
b) Stainless steel pot or plastic container (2-5) for measuring water (the soda will be mixed in here becoming a lye solution)
c) Stainless steel pot for oils (bigger because you’ll be heating the oils in this pot and also transferring the combined water and lye (lye solution) at the end when it’s time to mix)
d) Small dishes for measuring essential oils, herbs, powdered ingredients etc.
a) Stainless steel spoon for lye and stirring the lye in the water
b) Colander (sieve/strainer) for making sure there are no undissolved lye crystals before pouring it into the soap
c) Silicone spatula for stirring oils and pouring out the soap from pot to silicone mold
8) Luffa (or some other) sponge for washing the equipment afterwards
This does not have to be an expensive hobby; try to find as much as you can from your kitchen or second-hand stores, that way you are also encouraging circular economy.
Also, everything you use for soap making, including the immersion blender, should be used just for soap making. The kitchen scale is the only exception. Dishes for herbs and essential oils can also be from the kitchen. I do store them in the soap box so that everything is in one place but that is my personal preference not necessity.
Making a recipe on your own
The best option is to follow recipe you find online. You can also use calculators that exist on web, but I think it is crucial that you understand the relationship between the ingredients so you can check and calculate the recipe yourself to ensure it is correct.
To begin, always calculate the ingredients by weight, either grams or ounces. Because oils have varying densities, volume measurements like fluid ounces and milliliters are too incorrect. For example, one cup of olive oil is not the same as one cup of castor oil.
1) Oils in the recipe
Always start with oils, which one do you want and in what amount. For each oil there is an actual maximum amount advised. The total amount of oil is related to my silicone mold; I reach the top with around 1kg / 35.2 oz of total ingredients, so I always use 900g/31.7oz as the sum of my oils. In this case we will be making the basic and most famous castile soap, so only olive oil in
900 g / 31.7 oz. Once you’ve determined how much oil you’ll need, the recipe will fall into place on its own.
Maximal percentage in recipe
High level of fatty acids makes it good for conditioning, rich in vitamin A,B,D,E
Good lather. Vitamin A and E, high
oxidants, adds hardness to soap
Substitute for olive oil, creamy lather
Carrot seed oil
Easily absorbed by skin, moisturizing, creates lather
Coffee seed oil
Cucumber seed oil
Low shelf life, rich in antioxidants
Green tea seed oil
Hazelnut fixed oil
Hemp seed oil
Good for conditioning and moisturizing, does not lather, low at cleansing, makes soft soap, takes longer to trace and cure
Conditioning, stable lather
Pumpkin seed oil
Raspberry seed oil
Rosehip seed oil
High in antioxidants and fatty acids
Conditioning, vitamin E
Sweet almond oil
Gentle on skin, medium lather, rich in vitamin A & E
2) Lye in the recipe
Calculating the lye is easy because we use a simple formula. Each oil has its own saponification value (SAP), that’s the amount of lye it takes to turn 1 gram of oil into 1 gram of soap. You can find SAP tables on internet but I will link the one I use:
It’s a mathematical formula that looks like this: (oil amount) x (SAP value) = lye amount we need.
SAP value for olive oil for solid soap NAOH (it is different for liquid soap – KOH) is 0.135
So, in this case we use 900g / 31.7oz olive oil * 0.135 = 121,5g lye
Which means it takes 121,5g of lye to turn 900g olive oil into a soap.
It is important to note: you can`t swap oils in recipe just like that, for example: “oh I do not have olive oil I will just use sunflower oil”. You need the SAP value of that particular oil to figure out how much lye you should use.
The good news is that there are numerous calculators available online and I will put the one I use in the next section down below, but I’ll stick with the old method now.
3) Superfat / lye discount in a recipe
Now we have our exact amount of lye to make the exact amount of soap. However, we want more oils in our soap than lye. We must decide on a percentage of the oils that will not be transformed into soap, ensuring that there are more oils than lye and, as a result, a safe soap.
This can be accomplished in two ways: by adding extra oils at the end of the soapmaking process, therefore the name “superfat”, or by discounting the lye in the first place, while making a recipe, hence the name “lye discount”. Because it’s so easy to forget to pour the extra oil at the end, I prefer lye discount. It’s worth noting that adding essential oils and other colorants counts as superfat.
This is our fourth important factor when making a recipe. Oils, water, lye and what lye discount percentage will we use.
The lye discount rate ranges between 1 and 20%. The higher we go, the softer the soap becomes and the more likely it is that the oils will go rancid. The lower we go, the stronger the soap becomes and the more drying it becomes for the skin. Furthermore, a lesser percentage produces more bubbles. Anything from 5-10% is generally the best.
So, let’s decide that for our soap we will use 5% discount, which means we want to use 95% of lye:
0,95 x 121,5 = 115 g lye that will be used in our recipe
Another thing is that we and online calculators assume that we have 100 percent pure sodium hydroxide, which is quite rare, even if you bought it from the manufacturer. So, if we chose a minimum discount of 5%, it will actually be closer to 7 or 8%, which is fine too. I am saying this because if you by any chance forget to calculate the discount, it will still not be zero; instead, it will be around 2 or 3 %. .
If it is too drying for your skin when you use it, then use it for cleaning dishes or laundry as they are usually made with 0% superfat. I don’t recommend using soap in your washing machine or on your clothes in general, but this one batch won’t make a difference.
4) Water in the recipe
Water is not a precise measurement, not even in calculators. They will also give you a range from which we choose the amount of water.
You can calculate the water based on how much oils you have – as many internet calculators do – or you can calculate based on lye, as many soap makers do.
If you are calculating based on oil or on online calculator, aim at 30-35% of the total weight of oils. In this case we have 900 g oil which means 0,3 x 900 is 270 g of water.
If you are calculating based on lye, the most secure way is to take your lye amount and just multiple it by 3. In this case 115 x 3 = 345 g of water.
You can try to make a soap with less water which is known as “water discount”. This will result in a trace that appears considerably faster and has a shorter curing period, as well as preventing soda ash from accumulating on the soap. In that case you can go with multiplying by 2. In our case 115 x 2 = 230 g of water.
When you are making simple one colored soap with the olive oil being the majority of recipe, you can multiple the lye with 1.8 to get the even lower amount of water. In our case 207 g of water.
Now we finally have our recipe:
900 g of olive oil
115 g of lye
207 g of water
For olive oil soap that foams more and contains castor oil, click here.
Making a recipe with calculator
When using a calculator, the same principle goes, we need to know what oils we want and in what amount. No need to look for the SAP number, online calculator will calculate the lye and the water range for us.
We have to put the next points into a calculator:
1) Which sodium do you use (NaOH for solid soap, KOH for liquid soap)
2) What weight measurement are you using (grams vs. ounces)
3) What oil and how much (example 180 g sunflower oil and 720 g olive oil)
4) What is your lye discount (you are good to go if you put 5% every time)
5) What is your water percentage (you are good to go if you always put 33%)
6) How much of essential oil are you putting (do not go over 3% of total amount of lye and oils)
How to make a soap (procedure)
First step: measure your ingredients
Each in their own pot – lye, water and oil = three pots.
Second step: pour lye to the water
It’s critical that you don’t do it the other way around since it could provoke a reaction; always LYE INTO THE WATER. Make sure you are doing this step close to an open window and remove your head away from the pot.
Stir a few times with a plastic or stainless-steel spoon so the lye can dissolve in the water.
This is now called a lye solution, and it’s very hot, so we’ll set it away for 5-10 minutes to cool it down.
The goal is to combine this lye solution with oils when they’re both at a temperature of 30-50 Celsius / 86-122 Fahrenheit. They can be up to 8 degrees apart. If you are making a large batch, it is better to be closer to 35/37 Celsius – 95/100 Fahrenheit. When you see that lye solution temperature is around 51/52 Celsius then go to the third step and heat the oils.
Third step: heat your oils
We have a very hot solution as well as very cold oils. The oils must be heated, and they do so quickly, in my case in less than three minutes. Check the temperature of your oil with a thermometer to see if it’s close enough to the lye solution. Again, they can be apart up to 8 degrees.
Forth step: combine lye solution into oils and start to mix with immersion blender
Stir first with the blender off, then place it in the center, totally covered underneath, and turn it on without stirring. Stir only when it’s turned off. After a few minutes, you’ll notice “the trace,” which means, as already mentioned, the drops from the blender will no longer dissolve in the liquid and will instead cling to the surface. You can have a light trace – barley holding on the surface or a heavy trace – like a pudding. It will take a few minutes longer to get a trace with cold-pressed oil than with pomace oil. When you reach the trace, you are done.
Now is the moment to add colorants, herbs, essential oils, or oil if you haven’t already done the lye discount. After that we may pour our soap into the silicone mold and cover it with cardboard and then a towel for at least 24 hours, but 48 hours is preferable.
After 48 hours, remove it from the silicone mold, cut it into pieces, and place it on a rack to dry in a room that is not exposed to the sun for at least six weeks, although three months is preferable. This is also known as curing time, and it involves covering them with light paper or cotton sheets to keep them dust-free.
Why we need to cure our soap
1. Saponification – we have to cure our soaps so that saponification can be complete. Although the major of saponification happens in the first 48 hours, up to 5% of lye may still need to be converted into soap.
2. To dry our soaps – because there is still water in the soap, we must wait for it to evaporate This is especially true for hot processed bars, which, despite having completed saponification while cooking, contain more water than cold-processed bars and must be dried out even longer. You can also weight bars each week and when you see that they stopped losing weight (water), you can use it.
3. The longer you wait (three months), the better the lather will be, the soap will be less abrasive, it will clean better, and it will not be as soft, allowing it to stay longer in the shower. You can cut the curing time by using less water in the soap (multiply the lye amount by 1.8 to get your water amount) but even then don`t ever go under four weeks of curing time.
Note: the cure period starts when we sliced the soap into bars and put on the rack, not from the day we made a soap (48h earlier).
In the recipe of liquid soap we use potassium hydroxide (KOH), not sodium hydroxide (NAOH) like in solid soap. With that there is a different SAP value for the same oil. For example, SAP value of olive oil for KOH is 0.19 but the SAP value of olive oil for NAOH is 0.135.
The procedure to make a liquid soap is the same as for soap bars. They start to differ when we start mixing to reach a trace. While with NAOH we will reach a trace within a minutes, with KOH it will take us approximately hour and a half. We mix for one minute and then we let it rest for 10 minutes and we repeat this until we reach a trace.
Once we reach the trace, we are going to cook the soap in double cooking pot, meaning we will put the pot with soap in the bigger pot and fill the water of the bigger pot to the level of the soap. We cook for 1.5 – 2 hours. Stir occasionally and keep adding water to the big pot.
To see if it is finished, we slowly try the soap with the tip of our tongue. If we feel something similar to electric shock it is not done. If we just feel the weird taste then it is done.
After the soap is finsihed, we have two options:
1. Store the larger amount of soap in the jar for later and dissolve smaller amount with water or
2. Dissolve all of the soap in hot water
If we choose the second option, we leave the soap over night to melt in large amount of water, and next day we stir the soap until it is liquid, adding more boiled water if necessary. Store the finished liquid soap in the carboy.
For a liquid soap recipe please go here.
Rules for natural colors, herbs, essential oils and fixers
In the last phase, when you reach the trace, you can colour and beautify your soap with a range of plants and herbs, as well as other natural ingredients like clay. The same goes for essential oils, which react differently so you need to research for each one of them. Some herbs, for example, are best used fresh in soap, while others are best used dried. I’m not going to get into them since I want to make this instruction simple. I will, however, provide you with some general advice:
1) Color ingredients should make up no more than 5% of the soap
2) For every 454 grams (1 pound) of oils in your recipe, use 1-2 teaspoons of fresh herbs (thyme, lavender, rosemary)
3) The amount of essential oils in your recipe should be no more than 3% of the total amount of lye and oils
4) Scent fixers are used to “fix” the scent of essential oil so it smells longer. Some of the fixers are corn starch, oatmeal, arrowroot, kaolin clay etc.
5) Even when “scent fixers” are added, in most citrus essential oils (lemon, tangerine, orange), the scent does not last long. On the other hand, in may chang and bergamot does.
6) If you want a lighter color, make the soap at lower temperatures 35-37 C / 95-100 F. If you want a darker color make the soap at higher temperature 47-50 C / 118-120 F
7) If using clay, first mix it with distilled water (1 tsb clay to 1 tsb distilled water, if it is still pasty add up to 3 tsp water to 1tsp clay) to prevent crumbling or cracking (clay sucks moisture from the soap, creating crumbles or cracks). If it is single colored soap you can mix it either in lye solution or after in the trace. mixing it in the lye solution will give it more intense color. If the soap is swirled (with multiple colors), add it to the trace. 1 teaspoon per pound of soapmaking oils is the standard rate. If you want a lighter color, use less, and if you want a darker color, use more.
Too see some examples, check out my green rosemary soap or coffee and cocoa soap.
Cleaning the equipment after the soap making
1) While washing your pots and other utensils, keep your clothes, glasses, mask, and gloves on because lye is still present.
2) You can wash the equipment in your sink; the lye that remains is not a problem; in fact, lye is frequently utilized in other products to solve draining problems. If you have an option, I recommend washing it outside in the garden and drying it in the sun.
3) I have sponge only for this equipment. I use a luffa sponge, but you can use any sponge you have on hand. You may read about zero waste sponges in my previous post.