I really like making soap. My most recent soap creation is a homemade castile soap, made with olive oil and milk. The fluffy snow I see outside inspired me to make a light and gentle soap. When I use that first piece of soap from a new batch of all natural homemade soap, I get the same kinda satisfaction that my bug gets when she successfully puts a 4-piece puzzle together for the first time.
After working tirelessly to fit that initial 3 pieces together (with her tongue sticking out the whole time, because that’s how my 2-year-old concentrates), she looks at her last piece, looks at the 3 pieces that are on her little table, and looks at her last piece again. I think she’s saying to that final piece, “OK, we are gonna do this, now work with me, please.” She then gently wiggles the last piece into its place. And voila! She claps her hands, and all I see after that is pure joy and self-satisfaction.
That’s me when using my own handcrafted soap. I get that feeling of triumph and amazement every time, because I can’t believe I just made this awesome, all natural handcrafted soap! I made it through the simple process of mixing oil and lye! It’s so unbelievable.
The main ingredients for my newest creation, homemade castile soap, are olive oil and milk. Olive oil soap is renowned for its ability to clean without stripping the natural serum on your skin. Olive oil soap is moisturizing, hypoallergenic, and gentle enough for the most sensitive skin. Read more about olive oil soap here and here. Like olive oil soap, milk soap also does wonders for your skin. Milk soap is nourishing and gentle. Read more about milk soap here.
After looking into both olive oil soap and milk soap, I thought, why don’t I combine the awesome goodness of both soap into one homemade castile soap! At that moment, the picture of my bug kneading together two different colors of homemade play dough to form one even awesome-er play dough popped into my head.
Equipment Used to Make Homemade Castile Soap
includes affiliate links
- Crock pot – this is a must, because this homemade castile soap recipe is a hot process soap recipe. This means that the soap needs to be cooked in a crock pot. Yep, that’s why they call it crock pot soap. I got my crock pot at a goodwill store for a few bucks.
- Digital scale – it will help you figure out how much oil, milk and lye to use to create your homemade castile soap. Amazon sells this one.
- Electric stick blender – I commandeered my husband’s stick blender when I first started to make homemade soap. Maybe you can do the same from one of your love ones. Or you can look for one in a goodwill store. I use the stick blender to encourage the oil and lye to mingle and become all natural soap quicker. Some people (not many) do the mixing by hand. Yes, you can do that, but it will take you a long time (maybe around 30 minutes?).
- Glass measuring cups – you need them to make your lye solution. I use Pyrex 3-Piece Glass Measuring Cup Set. You can tell I love them. They appear in many of my pictures. These glass measuring cups are durable and easy to clean.
- Silicone spatula – you will use a silicone spatula to mix your lye solution, and mix your oil with lye. Look for some in a goodwill store. Are you sensing a pattern?? You can save a ton of money by first visiting a goodwill store or a thrift store for your equipment.
- Safety gear – gloves, goggles, an apron, a long-sleeve shirt, long pants and closed-toe shoes. You need to take precautions when working with lye. If you have never worked with lye, be sure to read this article and this article to learn more. I also discussed lye safety in my previous soap making posts, such as this one and this one. It’s a good idea to have plenty of vinegar around so you can neutralize the lye, if necessary.
Homemade Castile Soap Using Olive Oil & Milk
Prep Time: 2 hours (including about 1 and 1/2 hours of cooking the homemade castile soap in a crock pot)
Yields: 12 1-inch thick bars of homemade castile soap
Ingredients for Homemade Castile Soap
- Olive Oil – 33.8 oz. I use Trader Joe’s Imported Olive Oil. You can try Kirkland Signature Organic Extra Virgin Olive Oil, La Tourangelle Extra Virgin Olive Oil, or any other brands of olive oil.
- Whole Milk – 1/2 cup. Get it at your local supermarket. UPDATE: one reader reported that adding 1/2 cup of milk caused the soap to separate. If you are concerned about this, use 1/4 cup, instead of 1/2 cup, of milk.
- Lye – 4 oz. I use Food Grade Sodium Hydroxide Lye. Yes, it’s kinda crazy, but you can use 100% lye drain opener (Roebic Laboratories Drain Cleaner Crystals), which you can get from Lowe’s Home Improvement Store. This lye is not food grade though. It’s hilarious, but most of the reviews for this drain opener are from soapers.
- Distilled Water – 9 oz. Get it at your local supermarket.
- (Optional) Stearic Acid (plant-based) – 2 tablespoons. I used this stearic acid. UPDATES: Since making this soap, I’ve decided to stop using palm oil and palm oil derivatives, including stearic acid. Read more about my decision here.
- (Optional) Lavender Essential Oil – 2 teaspoons. I use NOW Foods Lavender Essential Oil.
- (Optional) Clove Essential Oil – 1/2 teaspoon. I use NOW Foods Clove Essential Oil.
How to Make Homemade Castile Soap
1. Wear protective gear please. Make sure no little ones are running around or anywhere near where you are working with lye and making soap.
As the pictures below show, the lye solution will start up cloudy then become clear after about 10 minutes.
As I was making this homemade castile soap, a historic snow storm, Winter Storm Jonas, was raging outside. It dumped a ton of snow and burying everything in sight. See the snow accumulation by the door?? That’s just a tinsy winsy bit of the total accumulation.
4. Add Lye Solution into the Oil. Stir slowly with a silicone spatula. Make sure you are wearing all the protective gear – gloves, goggles, an apron, a long-sleeve shirt, long pants and closed-toe shoes. You don’t want any of the lye solution or lye and oil mixture to get on your skin. It’s caustic and it will burn. If you accidentally got some on you, wipe it with vinegar, which will neutralize the lye.
5. After hand mixing the lye solution and oil with a silicone spatula, use a stick blender to bring the mixture to a pudding consistency, also known as trace. It took me about 10 minutes. You will see that the mixture’s color turns much lighter, like the color of vanilla pudding.
6. Cover the soap and let it cook.
7. Check the soap every 15 minutes or so to make sure it isn’t bubbling over the crock pot. Below is what my soap looked like after cooking at medium heat for 45 minutes. It looked like soufflé rising up from a cup.
8. (Optional) The little white pieces you see in the picture are stearic acid. I added it to make the homemade castile soap harder and last longer. I used plant-based stearic acid. You can also use other types of stearic acid or not use any at all. I have made many batches of soap without it.
UPDATES: I no longer use palm oil and palm oil derivatives (stearic acid) in my products. I don’t want to contribute to the harms that palm oil production has caused to the environment, animal and people. Read more about my decision here.
9. (Optional) If you add stearic acid, then cover the crock pot again and continue to cook the soap for another 10 to 15 minutes, until the stearic acid is completely melted. See that puddle of liquid at the bottom of the picture? That’s melted stearic acid.
10. Mix soap and melted stearic acid. Continue to cook soap with the crock pot lid on until it reaches a Vaseline-like consistency. It took me about 10 additional minutes.
11. Add Whole Milk, and mix well.
12. (Optional) Add Essential Oil.
13. Once the milk is mixed into the soap well, scoop your soap into a mold. I use a wooden mold that my wonderful and crafty husband made for me.
I have also used silicone molds. If you use a bread loaf silicone mold, be sure to use it with a frame, because the silicone mold is not strong enough to hold the soap. People have also used yogurt containers, paper orange juice containers and shoe boxes with great success. All you need is a container that’s sturdy enough to keep the soap in its place. Don’t use anything made with aluminum though, lye doesn’t like aluminum.
14. Once the soap is in the mold, bang the mold against the floor or a hard surface a few times. You want to get the air bubbles out of the mold. This can get loud, because soap + mold are quite heavy.
15. Let your soap remain in its mold for at least 1 day. Or if you are patient, leave it in there for 2 to 3 days. You want to give the soap a chance to harden. I have found that it takes longer (at least 2 to 3 days) for the soap to harden in a silicone bread loaf mold.
16. Once your soap has hardened, remove it from the mold and cut it into bars. I cut mine about 1-inch thick. I usually let the soap cure/dry for an additional week before use. This ensures that there will be complete saponification, and there won’t be any lye left in the soap.
That’s it! You now know how to make homemade castile soap with olive oil and milk! I used a bar from this batch for the first time tonight, and was giggly with triumph. I used the soap while bathing my little bug, and I was completely happy with my creation. The soap was very gentle and moisturizing. The olive oil and milk were working their magic on my little one’s skin.
The homemade castile soap produced tiny, white, silky bubbles and its lavender scent smelled amazing. My little one loved it too and couldn’t stop playing with it and making little bubbles on her hands. She rubbed, rubbed and rubbed her hands together, saying: “Look, mama! Bubbles. Bubbles.” She’s at the age when she does everything she’s excited about 10 to 15 times. I happily looked at the tiny bubbles on her hands 10 to 15 times.
In addition to this homemade castile soap, I have about 6 or 7 other types of all natural handcrafted soap curing/drying in our spare room. I have posted a few of my all natural hot process soap recipes: Rebatch Soap / Hand Milled Soap, Olive Oil Crock Pot Soap and Olive Oil & Coconut Oil Crock Pot Soap. For all three recipes I use the hot process method of soap making, that’s because I’m impatient, and don’t like to wait a long time to enjoy my soap. I’m an instant gratification kinda girl. I have also tried the cold process method and the cold process oven process (CP/OP) method. But both of these methods require me to wait 1 month to use my soap.
I hope you will give this homemade castile soap recipe or my other of soap recipes a try. Be sure to share or pin the recipes if you like them. Reach out and share your experience. As always, I’d happy to answer any questions you might have. Happy soaping!!