Why Does My Handmade Soap Smell Bad?

Ever had a perfectly made handmade soap smelling bad all of a sudden? This is a very common problem among the cold process soap process, and most soap makers, especially new soap makers, don’t really know why this happens. 

The main cause for your soap to smell bad is rancid oils. Another reason might be that the fragrance fade or changes in cold process soap. Sometimes with cold process soap, it tends to have a chemical smell at the beginning of the cure; however, this usually goes away after some time.

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You just finished with your masterpiece and notice during the curing process that your batch of soap has this awful lingering smell. What do you do? Throw it away? Leave it like this and hope it goes away once it’s done curing? Close your eyes, and hope you wake up from this nightmare?

A long time ago, I would have thrown it away because I didn’t know any better. However, today and after a lot of research, here is what I have come to learn.

What Makes Soap Smell Bad?

In most cases, the main reason for Handmade soaps tends to be butter with fatty acids that don’t turn into soap molecules. This may cause the fats to linger longer and eventually become rancid. This is, of course, for a soap that has passed its curing time. 

There are cases where your soap might smell bad even during the initial curing process. And this is the scarier part as this is where you simply would not know what has caused it as nothing should have gone rancid yet at that point.

So I made a list of the most common causes for soaps to smell bad. 

Oils And Fatty Acids Going Rancid

If you love using Shea butter, you might want to think twice before using it next time. All ingredients have an expiration date. However, some oils/butter tend to go rancid really fast. This is especially the case if you’ve added Shea butter to your soap. This butter is known to soothe dry skin. Understandably, many skin specialists worldwide recommend it. 

However, this butter is known to go bad really quickly. The average shelf life of an unrefined Shea butter is usually between 12-24 months. 

Its shelf life is even shorter if you leave at room temperature. And if you are not curing your cold process soap correctly, the chances are that it will start smelling bad before the curing process is finished. 

Oils and butter not saponifying

If the oils or butter is not saponified, you will most likely end up with a rancid soap. Not saponified means that the fatty acids in your soap didn’t convert to soap. So this means once your soap is ready to cure, these fatty acids are exposed and go rancid very fast over time, leaving behind a trail of very unpleasant smell.

This usually happens because you most likely did not use enough Lye in your formula, so the specification process could not occur. To avoid this, I would strongly advise using a soap calculator. 

Not Enough Essential Oils

Depending on the essential oil you used, it might be possible that its smell can fade or even entirely change within the soap. I would suggest staying away from artificial fragrances. 

I do understand that financially they are much more attractive. However, if you end up with a failed batch at the end, you would have wasted your money anyway. 

This is because the pH level of the soap attacks the oily component, which causes them to smell differently or, in some cases, just utterly bad. 

If you are new at making soap, a simple and yet effective way to solve, this problem is to use tested soap recipes. If you’re not, you can play around a little with some of the ingredients; however, I would advise, as mentioned earlier, to use a soap calculator to make sure you have the right measurements. 

Ventilating Your Soaps

A proper curing process is crucial when it comes to handmade soap. Cold process soap needs to be kept in a closed and moist and above all, well-ventilated space. If you fail at this stage, your soap may turn rancid and smell bad.

Your soaps should also not be wrapped tightly (or not at all), and they need space in between them. If you wrap them or seal them in a container, excess moisture may remain trapped, which leads to oxidation, DOS (Dreaded Orange Spots).

If you are not using a rack to let your soap cure which is used by most soap makers and the area is not well ventilated, you’ll probably end up with a failed batch.

What Does It Mean if My Handmade Soap Smells Bad? 

The cause for your soap to smell bad can be many and we already mentioned one or two. However, these two very common causes are 80% of the time, the reason for your soap to smell bad.

Rancid Soap

This is what we have discussed up to now. Your soap has gone bad, or at least the fatty acids have oxidized, and the soap has gone rancid. If this occurs, you should not use your soap because it may irritate your skin.   

If you already have used rancid soap once without realizing it, there is no need to worry; it will not harm you. However, repeated use can cause several ailments, so it is best to avoid it.

Evaporating Essential Oils

We also mentioned this briefly earlier. Another reason may be the fragrance of the essential oil is simply gone. In this case, you can still use your soap since it’s just the fragrance that has disappeared.

There are some cases, the outer layer of the soap has lost its fragrance, but the inner did not. The only way to found out if that is the case is by using the soap, and once you’ve used enough, your soap will shri5nk to a smaller size. You will eventually end up exposing the inner layer. 

I also want to mention that I completely understand that the point of using soap is so you’d smell good after using it, but with one that has lost its fragrance, you still have the function of cleaning and washing, so don’t throw it away yet! 

How to Prevent Scent from Fading in Homemade Soaps?

After reading the last part, you probably went (or are planning on going) online to search how to prevent scent from fading in homemade soap. Well, there hopefully will be no need for that if you keep on reading.  

Anchor Any Light Scents

The lighter you scent logically, the faster it will evaporate. This is the case for all fragrances. However, there are a few tricks to hold the scent for a much longer period.

Anchoring your scent is one way to keep them from fading. This means you pair it with a deeper anchor scent, and the anchored deeper scent will hold on to the delicate one. 

I know this may sound as if you need to relearn making soap again, but there is no need to worry. If you wish to know what scents qualify as good anchors, here are a few examples that will help you: Sandalwood Oils, Amber Oils, and even Patchouli oils make great anchors that will hold your delicate scents in place.

I know this list is limited, but after doing this a few times, you can start experimenting with other anchor scents.

Use Kaolin Clay

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Another really great way to retain scent on your handmade soaps is to use kaolin clay. You can use this in cold process soaps, and it will hold on to your natural fragrance oils as if you just poured it.

You only need to add a tablespoon of clay in distilled water to your soap during the cold process. On the plus side, this technique also adds a light, pleasant color to your soap. And if you do not like the color, you can use the first method instead. 

This method is also ideal for preventing your soap from smelling bad as it tends to absorb moisture. 


As with any soapmaking method, the temperature is where it comes down to. You see, fragrances have flashpoints. Flashpoint means that it has reached a temperature that actually changes your fragrance’s chemical structure, which sometimes makes it smell bad or not at all anymore.

If you are not using any thermometer when making soap, I’d suggest starting using it now. 

Each essential oil has a specific flashpoint. You can find a table below here to have an idea of some common oils flashpoint. 

Oil Type  Smoke Point (˚F)Flash Point (˚F)Fire Point  (˚F)
Canola Oil457619662
Coconut Oil385563626
High Oleic Canola oil464644680
Palm Olein446615666
Palm Oil489615666
Soybean Oil464626680
Cottonseed Oil450606680
Peanut Oil446633680
Rice Bran Oil444615695

This is a general overview of flashpoints. However, this may change based on the processing technique of the fragrance. 


Lastly, but surely, correctly storing your soap can also help you keep your scents longer. Storing them away from direct sunlight and in a cold and dry place is the way to go. It will stay put there for a long time, and the scent will take much longer to fade.

Is It Possible to Save Rancid Soap? 

Define rancid? What I mean is, some people tend to think that their soap has gone rancid, but in fact, it has just lost its scent. Rancid, for me, means that the oils/fats inside has gone bad.

DOS (Dreaded Orange Spots) might occur. If your goal is to sell soap, I would not recommend doing so. If it’s for self-use, I can cut away the spots and take the risk (usually not much of a risk). 

Final thoughts

Make sure to follow the proper guidelines on making soap but also correct storage. Stay away from artificial fragrances and always, always use a Thermometer to make soap to avoid flashpoint.

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