Does Soap Go Bad?

Whether it is due to rancid coconut oil in your recipe, too many wet additives such as fruit purees or fresh botanicals, or just the ravages of time, eventually all soap will develop the dreaded orange spots that show you how to tell if oil is rancid. Does soap expire? Not necessarily. It will remain a good cleanser pretty much indefinitely. But if you’re thinking this is one of the good uses for rancid olive oil, think again. Dreaded Orange Spots, often referred to as DOS, do not always appear alone. Sometimes they are accompanied by an unpleasant odor or a sticky brown film. The brown film rinses away easily, yielding a soap that continues to cleanse and wash away debris, the main functions of soap. It is the smell, when present, that will determine if soap is still useable, not the presence of dreaded orange spots. That’s right — while you wouldn’t want to give it away or sell it, it is perfectly fine to use your spotty soap for personal use if the odor remains pleasant.  

Imagine this scenario: you have prepared a fresh, new loaf of your favorite soap recipe. Because you are using a tricky or untested fragrance oil, you have chosen to use the full water amount with no discount. Additionally, you use oils that are nearing their expiration date — waste not, want not. What’s more, you have added one-half cup each of fresh mashed banana and avocado to your recipe. While your soap may look perfect at first, the combination of these various conditions leaves you at very high risk of your soap developing the dreaded orange spots earlier than most other soaps.  

If you are wondering how to tell if oil is rancid, the answer is simply to smell it. A rancid oil will have a harsh and unpleasant odor. If you were to venture a taste (not recommended!) you would notice a bitter taste that is not present in the fresh oil. The best way to avoid problems such as rancid coconut oil or olive oil in your soap is to make sure your oil is fresh, to begin with. There should be a stamp on the container indicating a “Best By” date, and that matters quite a lot when it comes to preventing the dreaded orange spots.  

In addition to using fresh oils for your soap making needs, it is important to pay attention to the rule of thumb for additives. If an additive contains moisture, use it to replace a portion of the water, ounce for ounce, in the recipe. That is, for each ounce of a wet additive such as fruit puree added as soap ingredients, you will reduce the water in the recipe by an ounce. This helps to prevent you from adding too much overall moisture to the soap, which can cause the oils to go rancid more quickly.  

Once it is time to cure your soap bars, be sure to store them in a cool, dry location with good air circulation. The sooner you can reduce the excess water in your soap bars, the better it will be for your chances of avoiding dreaded orange spots. Storing your bars naked for the first six weeks is the best way to lose excess water weight. After six weeks, additional water loss is minimal and the soap can safely be wrapped in your preferred manner. 

If you use a significantly higher-than-normal superfat (extra fat) amount, something in the range of 15-20 percent, this can also lead to dreaded orange spots. Sometimes, the rancidity shows up as areas of brownish orange stickiness on the surface of the soap. This is also dreaded orange spots in another form, and both forms indicate your oils have gone rancid. 

Once your soaps are fully cured, the best way to extend their life is to keep them cool and dry for as long as possible. Coolness will prevent the loss of scent, if any is used. Keeping the soaps out of direct sunlight will prevent fading of the colors and botanicals. And keeping your soaps nice and dry will slow down the process of rancidity in your oils, and will prevent mold on any botanicals you may be using.   

As you can see, there are a lot of things that you can do to reduce your chances of developing dreaded orange spots. Managing the little details such as the “Best By” date on your oils, the moisture level of your soap and the amount of superfat (extra fat) used in your recipe can lead you to the best possible outcomes in your soap making. If worse comes to worst, spotted soap that still smells nice can be safely used in your personal supply of soaps.