In the last post in the series, we figured out a simple castille soap recipe :

1 lb (543,6 g) of olive oil
2,0368 oz (57,74 g) of lye
3,0552 oz (86,61 g) of water

Now, we’re going to make this soap. First, using a digital scale, measure the olive oil in a large bowl as precisely as you can. You can buy pomace olive oil for this : it’s not very good for eating, but for soap it works just fine. Actually, it will be longer to stir the soap if you use high quality olive oil so I prefer to use pomace.

Again with the scale, measure the amount of lye in a small bowl. The water can be measured directly in your lye pitcher.

Add the lye to the water (NEVER add the water to the lye) in the pitcher. The lye will heat the water, wait until the solution is back at room temperature. Meanwhile, put the oil in a larger bowl if necessary. I mix my oils in a microwaveable bowl in case some of them needs to be melted, but it’s a bit too small to mix the lye.

When the lye has cooled down, pour the lye solution in the olive oil and mix.

And mix, and mix, until the soap mixture “traces”, or leaves traces in the mixture before disappearing. It’s a bit like doing whipped cream…

Pour the soap in the mold, and wait until it’s hard enough to unmold. It may take a few day depending on the temperature and humidity. I usually unmold while it’s slightly sticky, but holds its shape.

Let the cut soap dry for at least three weeks before using so it gets firm and mild. It may take longer depending on the heat and humidity in your home.

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A castille soap is simply an olive oil soap. It’s an easy soap to get started with since you don’t need to meld any oil and it reacts slow enough to see what’s going on. It takes a bit more time to harden than some other soaps to harden, but it will harden up nicely while being a wonderfully mild soap.

Ingredients

The only things you really need for this recipe is olive oil and lye. I usually use cheap olive pomace oil for soap. Pomace oil is obtained from the last pressing of the olives and is poor quality for food, but is great for soap. Since there are more impurities, you won’t need to stir as much. You could always try with the best quality extra-virgin oil, but you will have to stir alot before your soap is ready. Also, make sure that what you buy is 100% olive oil by checking the label carefully : some cheap brands sells olive oil mixed with canola oil and the results are unpredictable in that case.

The maths

Now, we need to figure out how much lye you need to use. Soap recipes are always in weight of oil. We’re going to do a small 1 lb (16 oz) batch, so we already know that we’ll need 16oz of olive oil.

Then we’re going to use a ratio called SAP that express the amount of lye needed to make the oil react completely. This ratio is different for each oil, but since we’re going to use only oil this is going to be easier. The ratio for the olive oil is 0,134 and is expressed in oz, so :

With this amount of lye, 100% of the olive oil will react, and we don’t really want to do that. You need to add a little safety margin to make sure all the lye has reacted with oil, with some extra in the soap so it will be milder. You don’t want too much though, or the soap will be soft and mushy. A 5% superfat, or 5% extra oil, is calculated this way :

It’s not a huge change since the batch is small, so you’ll have to measure as precisely as you can. The only thing left is to calculate how much water will be used. This is not as important since the water will evaporate, but too little will make it hard to dissolve the lye and too much will increase the time the soap takes to harden. A 40% solution is a nice compromise for most soaps. So, to calculate it :

The final recipe

To sum it up, the recipe will be :

1 lb (543,6 g) of olive oil
2,0368 oz (57,74 g) of lye
3,0552 oz (86,61 g) of water

You can double-check those calculations with the MMS Lye Calculator. The default values are fines, just write the amount of olive oil (in oz by default) and press “Calculate Lye”. The amount will not be identical, since SAP is a approximation and I don’t know which numbers they use. Next time, we’re actually going to make this soap.

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Even if making soap is a pretty basic process, there are many supplies you can use to make the soap of your dreams. Here are some of the choices available to you :

• Oils : Oil is the basis of you soap : if you don’t choose well, you won’t get nice soap. Fortunately, there are many good soap recipes available online to help you choose. You can use both animal and vegetable oils to make your soap. I usually make soap with vegetables oils : olive oil is nice for bulk, along with other oils like palm and coconut oils.
   
• Lye : Nothing to choose here, just make sure that what is you get is 100% lye if you buy it from the hardware store. A little lye will go a long way if you only make small batches, so don’t buy too much. This should be clearly labelled and stored in a safe and dry places so children and pets won’t find it.
   
• Scents : The two main ways to scent your soap are with essential oils and with fragrance oils. Essential oils are made for the real plants, while fragrance oils mimic the scent of real thing with chemicals. Fragrance oil are available in a lot more scents though and the price is the same for all of them, while the price of essential oils varies depending on the ingredients used.
   
• Colors : Colors can be added to soap with many additives : micas, clays, oxides and cosmetics colourants. Every other ingredient you add to your soap will also affect the final color, so you may be just fine with the natural color of the soap. Also, you should be careful when you use herbs and plant extracts since most of them turn will brown over time once they are mixed with the lye.
   


Pink and green clays

• Other additives : There are many other things you can add like milk power, herbs, flowers, coffee grounds and pumice sand. Each of them will add their own little thing to your soap.
   


From top left, going clockwise : goat milk powder, lavender flowers and pumice sand

A good soapmaking store will have those supplies available. I buy my oils locally since those can be expensive to ship and order my scents, colors and additives online from the Voyageur Soap & Candle Company in Canada.

In any case, you don’t need to add all those things make a great soap. One of my favourite soap is a simple 100% olive oil soap with clay : it hardens nicely and is wonderfully soft and mild on the skin. In the next post, I’ll teach you how to calculate the olive oil and lye you need, and give you the recipe.

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Most of the tools you need to get started in soapmaking can be found already in your kitchen. The important thing you need to remember is that all the tools that will be in contact with the raw soap or lye should be made of heat-resistant glass or stainless steel. Other metals, especially aluminum, will have a strong reaction to the lye and wood will chip. Strong plastics will last for a while but will eventually need to be replaced. Here is a breakdown of the most important tools you’ll needs

• Digital scale : All soap recipes are in weight because it’s easier to get consistent results that way. A 10% error can change the final product a lot and even make your soap unsuitable for use. Since you will likely make very small batches at first, you’re better off with a scale so you can get the best measure possible.
   
• Mixing bowls : You’ll need bowls for measuring and mixing the oils and additives used in the soap. Any old plastic bowl will do, but make sure you get one that’s microwavable so you can warm hard oils.
   
• Lye pitcher : Choose a strong heat-resistant glass or plastic pitcher that will only be used to mix the lye. I bought an old coffee carafe at the thrift store for this and only ever use it for soapmaking since it’s in direct contact with the lye. Check the pitcher carefully every time you use it to make sure there is no chips or holes in it and that the bottom is not wearing out.
   
• Soap pot : This is the bowl or pan that will be used to mix the oils and lye together to make the raw soap batter, so it needs to be big enough so you can stir it. Since the raw soap is still very caustic, you need a stainless steel or heat-resistant glass bowl so it won’t break down after a few batches.
   
• Spatulas and spoons : I like to keep a few spatulas and spoons handy to mix and handle ingredients as needed. A few measuring spoons are also nice for additives that don’t need to be weighted since they will only be used a teaspoon at a time.
   
• Molds : Many things can be used as a mold for you soap. To get started, a clean juice or milk box can make a nice mold : you only need to rip the box to get to the soap. Some people also use PVC pipes to make round soaps, but I have not tried it yet. I use small handmade wooden molds myself.
   


Homemade soap molds, one side can be unscrewed to remove the soap. Using painted wood was not a good idea though…

• Safety Equipment : Lye can burn the skin so you need to be careful. Rubber gloves, safety googles and a long-sleeved shirt and pants are a very good idea. Make sure you store you lye away from children and pets, and always put your lye and water solution in a safe place when it’s cooling. You don’t want to it to be mistaken for something edible…

When you’ve done a few batches, you may also want to get a stick blender. It will allow you to mix your soap a lot faster and less painfully than with the spatula, but you should still make your first batches by hand so you can see what’s going on.

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