5 Things You Should Never Do with Castile Soap

updated Jun 28, 2021
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Credit: Cat Meschia

Castile soap is a versatile, inexpensive, concentrated soap that comes in several scents. But, like most cleaners, castile soap comes with a list of don’ts. Knowing what you should avoid using castile soap for can save you from confusion, frustration, and lots of extra cleaning. 

Read more: What Is Castile Soap and How Does It Work?

Here are some things you should never do with castile soap.

1. Don’t mix castile soap with anything acidic.

Castile soap is made with oils, including olive oil, coconut oil, hemp oil, and/or peppermint oil, depending on your choice of scent. Mixing the soap with anything acidic causes the castile soap to return to its unsaponified state. Which means it reverts from being a soap to being a bunch of oils. Which means you’ll have oil clumps to clean from the tendrils of your mop. Yes, that is the voice of unfortunate experience talking. 

2. Don’t clean hard surfaces without following up with an acid cleaner.

Mixing castile soap and acid into one solution is a no-no. But! When you’re cleaning hard or shiny surfaces with castile soap, you’ll probably want to follow up with an acid “rinse.” That’s because castile soap can leave a salt residue behind, covering, say, your countertops in a white-ish film. Acidic cleaners — water and vinegar or lemon solution — are great at cutting through this residue.

3. Don’t use it with hard water.

Hard water greatly increases the residual soap scum. If you’re fine with cleaning the soap scum off, go for it. Again, a vinegar rinse does the trick. Otherwise use a water softener or skip the castile altogether if you have hard water so you don’t have to do double the work. 

4. Don’t over-use it on your plants.

Castile soaps is an ideal insecticide for house plants. But using too much or a solution that’s too strong can be counterproductive because it will remove the plant’s natural protective coating and make it even more susceptible to pests and diseases. Check here for instructions on how to make a castile soap insecticidal spray. 

5. Don’t store it for too long.

Castile soap is ultra concentrated so one big bottle can last a really long time. But remember that its shelf life is about three years. After this time, the oils can go rancid. (Again, voice of experience, here.) So don’t over-stock if there’s a sale because it can end up being money down the drain. When in doubt, check the expiration date on the bottle. 

Do you use castile soap at home? Tell us what you use it for.