Can homemade soap burn you?

Sometimes soap can burn you, especially the homemade type, giving you an itchy feeling or even irritating your skin. Why does this happens and how you can prevent it is what we will discuss in this article.

Can homemade soap burn you? Yes, homemade soap can burn you. This can happen when the sodium hydroxide (or Lye) used in making the soap has not been neutralized. As each oil has a different saponification value, wrong measurements may lead to an incomplete saponification process. Finally, the lack of glycerin may also cause burning or skin irritation.

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Ever had soap that left you with a burning sensation? Or maybe got your skin irritated? Making your own soap can be fun, but if you are new to it, you might end up with a product that will not only irritate your skin but even burn it. This usually happens due to the formula used to make soap was not balanced or calculated correctly.

However, some people might have the same reaction even with some types of commercial soaps. Of course, you could easily solve that by buying a different brand or checking what chemical is causing this reaction. But with homemade soap, things are a little different.

Why is homemade soap harsh to skin?

If you see your skin reacting in a certain way to your homemade soap you worked so hard on, you probably need to check if your calculations are correct. What I am trying to say is, the amount of sodium hydroxide in the recipe you used might be too much, and therefore the mixture of oil and sodium hydroxide could not turn into soap.

Each oil has a different saponification value, and you need to make sure the calculations are adjusted to that specific oil. If it’s not done correctly, then the lead cause of skin irritation is most likely the sodium hydroxide (or Lye).

There might be other reasons causing irritation or burns on your skin.
For example, the lack of Glycerin in soap is another common cause of dry and irritated skin. Glycerin is a skin softener, and without it, your soap would be too harsh on your skin and cause irritation after prolonged usage.

As I mentioned earlier, some commercial soaps may have the same effect, and the reason for that is because many of them remove Glycerin (to be used in cream and lotion).

In case you are making your own soap, and you think it needs more Glycerine, you can add extra to your soap; however, this should not be necessary as it occurs naturally during the saponification, so you should not need to do so.

How do I know if my soap is safe?

So we talked earlier about what would happen if you use too much Sodium hydroxide and what it leads to. But, what if you already made your soap and now you’re worried if it’s safe to use?

Well, there are ways to test if your soap is safe or not but, before we dive into that, we first must know what we’re actually testing.

Sodium hydroxide lye has a pH level of about 14, and once it goes through the saponification process, it lowers to around 9-10. 14 is too high and will cause irritation or burn. But as we already discussed earlier, if the measurement is not correct and you use too much of it, the pH level will rise accordingly and will finally be too high to be used as a soap.

So the thing you’ll be testing will be the pH level of your soap, and you can do this in two ways.

The most commonly used method to test the pH level of soap is using a pH strip. The procedure is quite straightforward; If you wish to test cold processed soap using pH strips, you would need to wet the soap with some distilled water and make some bubbles by rubbing it as you would do when washing your hands.

Then you’d need to place the strip on the wet soap to get the reading, and that’s it. Please note that this technique only works with distilled water and not with regular tap water.

In case you don’t have pH strips with you, you can use the “zap test” technique, which includes placing the soap on the tip of your tongue. When and if you feel a very slight zap (the same feeling when you lick batteries), then it means that the soap is lye heavy.

How can I avoid this?

Using the right tools:
By now, you probably have guessed that using the tools that help you get accurate measurements is crucial when making soap. This means using a scale to measure everything. It is preferred to measure by grams (but that’s more personal preference) as it gives a much more accurate measurement.

Do not try to measure using a teaspoon or a cup. You could easily fail and end up with too much lye in your soap.

Use a soap calculator:
I would say this is a must for every soap maker out there, using a soap calculator will allow you to calculate whether your soap is lye heavy or not. There are many calculators out there, but here is one I would recommend.

Follow the recipe to the letter:
If you find a recipe online but wish to change some things, I would not suggest doing that unless you know what you are doing. Professionals have tested these recipes, and the measurements should be followed, if you fail to do so, you might end up with too much lye in your soap.

Red (purple) cabbage:
If you don’t have pH strips or you don’t want to use your tongue (totally with your there), there as an alternative way to get this done. Red cabbage (or some know it as purple cabbage) can also be used as an indicator. You do this by placing the juice of the red cabbage on top of the soap, and it will change color depending on the pH level.

Here is how you can prepare it:
Cut 4-5 leaves of cabbage into small pieces and place them in a big bowl, add distilled water to it; this only works with distilled water. If you choose to do it with regular tap water, this will most likely not work because tap water might have microbes or even bits of metal in it, which affects the test results.

With a stick or a blender, puree the cabbage and strain out the cabbage pieces and discard once done, and voila you have your liquid!

How Safe Is Lye Soap?

Lye soap can be very safe; that is if the formula and measurements are adjusted to the type of oil and the saponification process went correctly. Taking your time and measuring everything the right way will lower the chances of having a soap that is too heavy on lye.

Is homemade soap better for your skin?

I have mentioned in this article that some commercial soap might give you the same reaction and why this happens. This is one of the most significant differences between commercial soap and homemade. Glycerine is something we all need, and without it, you most likely will have irritated skin.

Since Glycerine naturally occurs during the saponification process, and we do not remove it like those big manufacturers are, I would say homemade soap is even safer than regular soap.


If you use the tools to measure everything in gram and follow the recipe as stated, you should be fine. In case you already made a big batch and are concerned if it’s safe to use, do a test using one of the methods mentioned above.

Finally, if you are wondering if it’s better to use homemade soap instead of commercial ones, then the answer to that is a resounding yes. Handmade soap is not only more natural, but it’s simply better for your skin.

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