20/09/2026
KOJIC ACID IN TRADITIONAL SOAP. USEFUL OR NOT USEFUL? SENSE OR NO SENSE?
Let's talk about this. 👇 👇
I've been meaning to talk about this for some time now but somehow, it always slips my mind
Before we start, what is kojic acid?
Kojic acid is an ingredient, an active ingredient, that is mostly used in skincare products to help with pigmentation, dark spots, uneven skin tone and all that. It is mostly used in cosmetics, in creams, serums and other skincare products.
Now, before we come to traditional soap, we already understand the role of cosmetics. We understand stability, pH compatibility, temperature and all those things we have to consider when making a product.
So now, back to kojic acid
One thing you must know about kojic acid is that it is very sensitive to heat, light and pH. So you have to be careful with the kind of formulation you are putting it in.
That is why in products, like creams and serums, you don't just throw your kojic acid into your formulation while everything is still very hot. You normally add your active at the appropriate stage and temperature, depending on the formulation.
Now let's talk about pH.
Kojic acid is more stable in an acidic formulation environment, and pH is one of the things you have to consider when formulating with it.
So now, let's come to traditional soap.
Traditional soap on its own is alkaline. You are looking at a pH that can be around 9 to 10, depending on the soap and how it is made.
So now, let's talk about putting kojic acid inside traditional soap.
If you understand pH, you will understand the problem.
You are taking an active that has stability considerations around pH, and you are putting it inside an alkaline soap environment.
So what happens to that active?
Will it remain stable?
Will it still be effective?
That is the question.
Now, aside from the pH difference, let's talk about heat.
Whichever way you make your traditional soap, whether hot process or cold process, saponification has to happen for soap to form.
And saponification is an exothermic reaction.
Meaning it releases heat.
So if you have an ingredient like kojic acid that is very heat-sensitive, you have to ask yourself:
Will that kojic acid actually survive the soapmaking process and still remain stable and effective in the finished soap?
Now somebody might say:
I can use melt and pour because the saponification has already happened."
Okay.
But even then, the pH of the final soap still comes into play.
Traditional soap is still alkaline.
So the pH compatibility issue has not just disappeared.
The point is, kojic acid in a hot or alkaline environment will surely degrade.
When it degrades, you can lose a significant part of the active's effectiveness, and degradation can also affect the stability and skin tolerance of the finished product.
So here's another thing
If you are somebody who prefers actives in your wash-off products you like kojic acid, niacinamide, arbutin and other actives in your body wash or cleansing products that's fine.
But traditional soap is not be the best type of formulation to use for that purpose.
You can look at things like syndet bars and properly formulated shower gels, because these are made differently from traditional soap.
They use surfactants, and the formulation pH can be controlled to a range that is more suitable for certain actives.
And another thing is that these products don't go through the same soapmaking saponification process.
But remember, they are still wash-off products.
So even when you put an active in a wash-off product, you have to consider how long it stays on your skin and how much of that active is actually available to do what you want it to do after rinsing off
So this is where I'm going to stop.
Kojic acid in traditional bar soap — useful or not useful?
Sense or no sense?
Let's talk about it.
What do you think?
Yole's Craft
