People have been using Castile soap now for almost 500 years. Soap has traditionally been made of animal fat and lye, but in the Castile region of Spain, people made it with olive oil instead.

Today, Castile soap may contain other oils, such as hemp, coconut, jojoba, palm, avocado, walnut, or almond, but it remains a soap based on vegetable oil and not animal fat. That gives it a special appeal to vegans.

The original Castile soap was a hard, white soap sold all over Europe as early as the middle of the 16th century.

It still comes in bar form, but most people prefer the liquid form. It’s easier to use but a little more expensive.

Grocery stores, big box stores, and health food stores all carry Castile soap. Liquid Castile soap is highly concentrated. You will either dilute it with water or use only a little bit, sometimes only a few drops. You can purchase containers as large as a gallon. It keeps for three years. If you have access to a zero-waste store, you can refill any container you have. Therefore, it’s very affordable and creates little if any waste.

Like many pre-industrial cleaners, versatile Castile soap has many uses. It is also biodegradable and non-toxic. It as well as the more familiar brand-name products. Fully biodegradable, it has no synthetic foaming agents, preservatives, detergents, or other harsh chemicals. And Dr. Bronner’s brand, at least, comes in containers made from 100% recycled post-consumer plastic.

So let’s explore how to use Castile soap, but first, how not to use it.

Castile soap warnings

Although Castile soap is easy to use, you need to avoid common mistakes:

Don’t mix Castile soap directly with vinegar, lemon juice, or any other acid. They will neutralize each other and curdle. If you try to use the mixture, it won’t do much but leave a film behind.

On the other hand, when you use Castile soap on a hard surface such as floors, countertops, or dishes, always rinse it with vinegar or another acid. Soap and the minerals in water combine to make a scum. The acid rinse removes it.

If you have extra hard water, the soap scum problem becomes worse and the vinegar rinse more important.

Unless you like the thought of soap scum hardening in your hair and tangling it, don’t wash your hair in Castile soap without a conditioner. Apple cider vinegar works well for the purpose.

And if you color your hair, Castile soap can strip away the color. Stick with color-safe shampoo.

Using Castile soap for cleaning

I have seen some of the following suggestions in more than one article. Recommended proportions differ from source to source.

Basically, then, pay attention to whether they recommend diluting the Castile soap a lot or only a little. Make adjustments according to what size container you’ll put the mixture in.

These recipes all assume you’re using the liquid version. I have omitted most references to adding essential oils. You can easily find Castile soap that already has your favorite scent.

1 Dish soap for handwashing dishes

One part Castile soap to ten parts water makes a good liquid dish soap. It won’t make suds, but the suds in regular detergents are just for show. Be aware, however, that any soap interacts with the minerals in water to leave a scum. Rinse the dishes in a sink of water with added vinegar to prevent it.

2. Dishwasher detergent

Mix 1 cup of Castile soap and one cup of water in a glass jar and shake to combine. The recipes I have found recommend adding lemon juice, but all that accomplishes is neutralizing the soap.  In your dishwasher, put one tablespoon of the mixture in the open compartment and a cup of vinegar in the closed compartment.

A cup? I don’t think I’ve seen a dishwasher compartment that big. Obviously, I take a dim view of this idea. I’m including it only because plenty of people may want to try it.

3. Laundry detergent

No, it’s not really a detergent. It’s soap. Some people find that detergents give them a rash. Use a third of a cup to half a cup of Castile soap instead. Use half that amount in a high-efficiency washing machine. Or you can make a powdered soap by mixing a cup of grated soap with four cups of baking soda. In either case, be sure to add ½ cup vinegar to the fabric softener dispenser for the rinse cycle.

4. For handwashing delicates

Add a capful of liquid Castile soap to a sink of cold water. Swish your delicate garments in it and soak them for 10 minutes. Then swish them again and rinse in clean water. For silk and wool, add a cup of white vinegar to cold water and swish the garments in them and then rinse in clean water.

Do not wring the garments out. Roll them in a towel to remove excess moisture. Hang up lighter fabrics to dry. Lay heavy or stretchy fabrics flat on a dry towel.

5. All-purpose cleaner

One or two cups of Castile soap in a quart of water makes a good cleaning spray. Just don’t use enough of it to leave scum behind.

6. Window and mirror cleaner

One tablespoon of Castile soap in a quart of water in a spray bottle shines your windows and mirrors. Again, you will need to rinse them with vinegar.

7. Cleaning wipes

Mix a cup of water and 2 tablespoons of Castile soap in a one-quart mason jar. Add 8-10 cleaning cloths. You can buy cloths or cut up old towels and tee shirts to make your own. Screw on the lid, and saturate the cloths by shaking the jar gently. They’re ready for use on any mess. And, of course you can toss them in the laundry when your finished and use them again the next time you need wipes.

8. Mopping

Mix ½ cup of soap in a 3-gallon bucket of hot water . When you’re through mopping, rinse the mop and then rinse the floor with a vinegar mixture.

9. Toilet cleaner

A cup of soap to 4 cups of water in a spray bottle – Turn off the water to the toilet and empty it. Spray the bowl and sprinkle baking soda on top and scrub with a  toilet brush. After 10 minutes, turn the water back on and flush.

10. Scouring scrub

Shake some baking powder on an area that needs cleaning, spray with diluted soap (1 part soap to 3 parts water) and scrub. Or you can mix 2 or three tablespoons of soap and ¼ cup baking soda and scrub with that.

Using Castile soap for personal hygiene

11. Soak in the bathtub

Add two tablespoons of soap to your bathwater for a luxurious, relaxing bath. There’s no need to worry about soap scum on your body from using Castile soap. No other soap needs a vinegar rinse after a bath!

12. Foot bath

Treat your feet to a nice 20-minute soak with 2 teaspoons of liquid Castile soap to  hot water.

13. Body wash  and exfoliant

Rub a small amount on your wet body in the bath or shower and use a washcloth or loofa to exfoliate your skin. Rinse and dry as normal.

14. Foot and body scrub

For a moro thorough scrub, combine 1 tablespoon Castile soap, 2 tablespoons of coconut oil and 1 cup of sugar. It will scrub away dry skin anywhere on your body.

15. Face wash

Castile soap is very gentle on your body. Rubbing a few drops on your face can kill bacteria and help prevent acne. Any soap can be drying, though, so be sure to rinse well.

16. Liquid hand soap or foaming hand soap

Mix 2 tablespoons of Castile soap and fill your soap dispenser. The design of your dispenser determines whether it foams.

17. Shampoo

You can mix one tablespoon of Castile soap with one cup of water or just work a small amount of undiluted soap into wet hair.

Some time ago, I read a post by women who sold soap-based shampoo because they distrusted the detergent formulas of regular shampoos. I wondered what they thought of dried soap scum in their hair.

If soap for your hair seems like a good idea, rinse it with vinegar.

18. Shaving cream

A little undiluted Castile soap lathers up nicely to replace shaving cream. Wet your hands, add a few drops of soap, rub until a nice lather forms, and apply to wet skin.

19. Makeup remover

Mix equal parts Castile soap, witch hazel, and a carrier oil and use a cotton ball to remove makeup. Scrubbing with a warm wet washcloth will exfoliate your face and rinse away the residue.

20. Makeup brush cleaner

Once a week, wet your makeup brushes in water, then soak for about 10 minutes in a cup of warm water with a few drops of Castile soap. They rinse again and let them air dry.

21. Baby wipes

Using a long serrated knife, cut a roll of thick paper towels in half. Use recycled ones if you can find them, but just make sure they’re sturdy enough not to disintegrate when you use them. Then put half a roll upright in a sealable, airtight container. Bring two cups of water to a boil and stir in 2 tablespoons of liquid Castile soap.

You can either use scented soap or add a few drops of your favorite essential oil to unscented soap. Adding a little calendula benefits sensitive skin by providing additional moisturizing. Pour the water over the paper towels and seal the container.

After 10 minutes, pull out the cardboard tube. A sheet of treated paper towel will come out with it. Continue to pull wipes from the center every time you use one. Be sure to replace the lid.

If you prefer reusable cloth wipes, cut squares of cloth from clean rags and stack them near the changing table. Mix 3 tablespoons of olive oil, 2 tablespoons of Castile soap, and 1 tablespoon of pure aloe vera with 4 cups of water that has been boiled and cooled. Pour it into a squeeze bottle. Wet the cloth with the mixture. Toss it in the diaper bin with the dirty diaper and launder as usual.

Not recommended!

I have found recipes for how to use Castile soap as toothpaste, mouthwash, and underarm deodorant. No thank you! I don’t want to wash my mouth out with soap or put any soap on my skin I can’t rinse off.

Miscellaneous uses for Castile soap

22. Fruit and vegetable rinse

Soak fresh fruits and vegetables in a bowl of water with ¼ teaspoon of Castile soap and gently rub to remove pesticide residue. Then rinse in plain water.

23. Wound cleaning

A solution of 2 teaspoons of Castile soap and 2 cups of filtered water effectively heals many wounds and lowers the rate of complications. The chief exception is for cleaning open fractures. In that case, a saline solution offers better protection against the need for a second surgery.

24. Sinus decongestion

Bring some water to a boil, lower or turn off the heat, and add a tablespoon of Castile soap. Drape a towel over your head, bring your face near to the water and breathe the steam.

25. Pet wash

Mix a small amount of soap with the water in a washtub to bathe your pets. Essential oils can be toxic, so use only unscented Castile soap for this purpose.

26. Ant spray

Keep ants off your plants—houseplants or garden plants––with a Castile soap and water mixture. I have seen both ¼ of soap and one tablespoon per quart of water. Try the lesser amount first. You want it to have enough soap to kill ants but not enough to damage the plants.

The soap may remove the natural waxy coating that protects the plant. That makes it more susceptible to disease and can even burn the leaves. To make sure it doesn’t damage the plant, test it on a small part first before spraying the entire plant with it.

Sources:
25 uses for liquid Castile soap / Sarah Flowers, Green Cleaning Hacks. July 27, 2019
Castile soap: a miracle product for both cleaning and beauty? / Emily Cronkleton, Healthline. July 29,  2019
Don’t fall for these 6 common Castile soap cleaning mistakes / Ashley Abramson, Apartment Therapy. October 16, 2018
What is Castile soap? Uses and benefits / Katherine Martinko, TreeHugger, March 20, 2020