Olive Oil Soap (Castile Soap)

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Why use the Olive Oil Soap or Castile Soap for skin care?


  • Pros

- Very moisturising

- Hypoallergenic (for people with sensitive skin)

- Acne treatment

- Antioxidant

- Rich in Vitamin E

- Wound cleaning

- Suited for babies skin

- Vegan

  • Cons

- Can't be used straight away, needs a few weeks to unmold and cut.

- Fresh cold pressed virgin olive oil may be hard to find in some countries (Buy it in my store, or if you are from the US or India, click here)

How to do it



- 500mL or 450g (2 cups.) of Extra Virgin Olive Oil

- 150mL Water

- 5-10 drops essential oils of choice

- 58g Sodium Hydroxide (lye) - Safety note at the bottom, click here

- Mold (any container will do, silicone is recommended over any other plastic)


(Check below for other quantities, click here) 




1. Place the water in a heat resistant container. Slowly add the lye to the water. Careful! It will heat up. Stir until it has fully dissolved (the mix will be clear like water again), keep checking the temperature while adding the Sodium Hydroxide. Let the mix cool.


2. Once the lye and water have cooled down to 55ºC (130ºF), add it to the olive oil and mix thoroughly. It will slowly start "tracing", which means it will acquire a consistency. How fast it traces will depend on what you are using to mix. A stick blender or a blender will make it trace much faster (2 min) than mixing it manually (30min-2h). In other soaps, timing is essential since if it traces too much then it is very difficult to pour into molds, but since this soap is made purely of Olive oil it doesn't have that problem.


3. Add the essential oils now. Mix.


4. Pour into the mold. Some people use their oven trays, but make sure you use a non-stick paper.


5. Let it sit for one to two weeks until it's hard and you can unmold it properly. Since olive oil is liquid at room temperature, Castile Soap takes longer than other soaps like the ones made with coconut oil, which is an oil that is solid at room temperature.


6. Unmold it and cut it in pieces and let it cure for at least 4 weeks more, that will allow it to have more lather and consistency (some people leave it for up to a year). 

Get the ingredients to DIY!

My store

U.S. and India

I am very happy to see that so many people from the US and India are watching! Unfortunately, the shipping costs are ridiculously expensive. I can still ship it to you if you buy through my store, but it can cost up to 30$. But that has an easy solution! I chose the best ingredients for you in your respective Amazon stores so you don't have to browse through thousands of items, plus if you buy through the links below I will receive a tiny portion of the price, and you'll help me keep this site and my little Beauty and Science project running.

United States


- Olive oil


California Olive Ranch Arbequina Extra Virgin Olive Oil, 16.9 oz

This oil has passed all the Extra Virgin tests. It's made in California with olives that are typical from the Mediterranean basin (the climates are very similar). It's also cold pressed. It's a good choice if we want to make sure that our soap preserves all the benefits of pure Olive Oil. Click here to buy 16.9oz or 500mL, the exact quantity you need for the recipe.


- Soap molds


Set of 2 - CHICHIC 6 Cavity DIY Rectangle Soap Molds, Baking Mold Cake Pan, Biscuit Mold, Chocolate Mold, Ice Cube Tray for Homemade Craft

You can never go wrong with the typical rectangular soap bar mold.



Bakerpan Silicone Mini Cake Pan, Muffin Baking Tray, Pastry Mold, 2 1/2 Inch Hearts, 8 Cavities

Heart shaped mold, just like the one in my video! Ideal for gifts.



Peicees Adjustable Wooden Soap Loaf Cutter Mold + 2 Pieces Stainless Steel Cutters + Rectangle Silicone Mold with Wood Box

If you want to go classic, use this high capacity wooden mold that has the tools for professional clean cuts.


- Lye


RED CROWN High Test Lye for Making Award-Winning Handcrafted Soaps 2 lb. (1, Non-Food Grade)

You can find lye in any supermarket as drain cleaner (make sure that in the ingredient list in only says: Sodium Hydroxide). But why not get it shipped at home with the rest of the ingredients? This brand has been used for years in soap making!


- Essential oils


Radha Beauty Aromatherapy Top 6 Essential Oils 100% Pure & Therapeutic grade - Basic Sampler Gift Set & Premium Kit - 6/10 Ml (Lavender, Tea Tree, Eucalyptus, Lemongrass, Orange, Peppermint)

This is a great deal that I found, consisting of 6 essential oils that will give a nice perfumed touch to your Olive Oil soap. You can mix them or just use one. We use essential oils in nearly every DIY, and only a few drops at a time, so you'll be able to use them for a long time!





- Olive oil


Colavita Extra Virgin, 500ml

Extra virgin and cold pressed from European Olives, from an Italian family-run company. It's a good choice if we want to make sure that our soap preserves all the benefits of pure Olive Oil. The exact quantity you need for this recipe!






- Soap molds


Joy Global 6 Cavity Basic Rectangle Silicone Mold 6 Cavity Petite Silicone Mold for Homemade Craft Soap Mold, cake mold, Ice cube tray

The typical rectangular soap bar mold, with rounded corners that give it a very nice finish.


JoyGlobal Happy Birthday flower Rose Heart Cartoon Soap chocolate fondant bakeware mold

A mold with different beautiful floral shapes, ideal for presents and special occasions!


 Flexible Rectangular Soap Silicone Mold Wood Box for Homemade 42oz Soap Produce

If you want to go classic, use this high capacity wooden mold. Wood helps in the process of soapmaking because it isolates the mix better. The cutting tools are not included. 



Soap Mold Loaf Cutter Adjustable Wood and Beveler Planer Cutting -

A great addition to the previous soap wooden mold. This will make professional clean cuts to your soap.




- Lye


CERO DRAINCLEAR 100% Pure Lye (DRY POWDER) to Clear Clogged Drains, Sinks and Pipes (200g)

This drain cleaner is high purity lye, exactly what you need for making your soap! This is no different from the lye that is labeled for making soap.


- Essential oils


Pure Source India Good quality 9 In one aroma oil pack (Lemon Grass , Lavender , Jasmine , Rose , Citronella , Eucalyptus, Peppermint ,Sandal Wood , Relaxing 10 ML each )

This is another great deal, for the price of two bottles of essential oil you can get this 9 different oils that will give a nice aroma to your Olive Oil soap. You can mix them or just use one. We use essential oils in nearly every DIY, and only a few drops at a time, so you'll be able to use them for a long time!


 Other Quantities


If you want to make soap with other quantities, it's really very easy! Just scale all the numbers the same.

So if you want you can multiply the recipe by 2, and you'll get double the soap:


- 1 L of Olive Oil

- 300 mL of Water

- 116 grams of Lye


Let's say you only have a little bit of that olive oil you bought a few months ago. I'll show you how to scale the recipe so you can use all of it, it's three easy calculations.


Instead of 500mL you have 300mL of oil. Divide   300 / 500 = 0.6

Now you just have to multiply 0.6 by the other ingredients. So:

150mL of Water  *  0.6  =   90 mL of Water

116 grams of Lye  *   0.6   =   69.6 grams of Lye



The idea is dividing the ingredient that you have the least of, by the quantity in my original recipe, and multiply the result by the rest of the ingredients. This way you can also scale the recipe if you are running short of Lye.





You can use this calculator if you want other quantities or maybe add some other oils to it. 



Information and safety note about lye


This may seem like something very complicated and scary, but trust me, it's not! There's only a few things you have to take into account, and they are really similar to the safety precautions you have to take when you boil water or heat up oil to fry something!


Sodium Hydroxide is a chemical used in every single soap, which gets converted into soap and glycerine once we mix it with the oils in a process called saponification, there will be absolutely NO lye in the soap.


Sodium Hydroxide in the pure form isn't dangerous if we handle it with care. If you follow this instructions it is very easy to avoid any accidents, take your time and re-read them right before using the lye.


I recommend you use: goggles, long sleeves and gloves. Other extras: mask, long pants, covered shoes (no sandals).


When mixed with water, lye releases heat, that is why it's important to always slowly add the lye to the water, and never add water to lye (that would cause all the heat to be released at the same time and the lye to expand, which would probably crack the container and splash everywhere). That is why we will use a heat resistant glass container like pyrex or a container made out of thick plastic. Lye can even eat through glass thick glass after many many uses, so if you plan on making soap for the next few years, use plastic. You can also use a metal container, but lye reacts with certain metals like tin or aluminium, so don't mix water and lye in a metal container unless you are sure it's stainless steel (it is safe to pour it in a metal tray later to let it harden since there will be no lye in the mix but use a non-stick roll of paper anyway or once it hardens it will be very hard to get out of the tray).


It is best if you are in a ventilated area and you avoid breathing in the fumes, for example by working under the kitchen hood or by opening opposite windows. Rinse the container that you used for the lye several times with water once you are done. You can also do a vinegar rinse. Lye, which is a base, will get neutralized by vinegar, which is an acid. The same goes for any lye spills on the counter, just pour vinegar on it and wipe it off.


In the event that after all the precautions, lye still comes in contact with any part of our body, flush immediately with plenty of water for at least 15 minutes and seek medical attention. If you have accidentally poured it on your clothes, quickly remove them and proceed to rinse the skin underneath. Don't use vinegar on wounds.

Get all the supplies you need to DIY

Extra Virgin Olive Oil 500mL
Bottle of Extra Virgin Olive Oil, cold pressed and un-refined. Olive Oil in its purest form. Produced by local growers in Spain, I have personally seen it produced from start to end. Very limited production per year since it's from ... (Read More)
14,99 €
Olive Oil Soap Pack (Castile Soap)
All you need for the: Olive Oil Soap (Castile Soap) DIY Tutorial    Includes:   500mL Extra Virgin Olive Oil - Locally Produced in Spain 1 Heart Shaped Mold 10mL Lavender Essential Oil   1 ... (Read More)
29,99 €


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