If you’ve been working with natural soap colors for a while, you’ve probably noticed that some botanical colors soften over time. A bright shade may mellow slightly, or a deep tone may lighten after months of curing.
This is completely normal.
Natural soap colors come from plant pigments, and plant pigments naturally change over time when exposed to things like light, heat, and oxygen. Understanding why this happens — and how to slow it down — can help you enjoy beautiful botanical colors for a long time.
Botanical Pigments Naturally Change Over Time
Botanical soap colorants come from the same pigments that give plants their color in nature. Roots, seeds, leaves, and flowers contain compounds that react to their environment.
When those pigments are placed into soap, they enter a completely different environment than the plant originally grew in. Soap is alkaline, it generates heat during saponification, and the finished bars continue to cure and interact with air.
Because of this, some botanical colors slowly evolve or soften over time. This doesn’t mean anything is wrong with the soap — it’s simply how natural pigments behave.
If you’re curious about the different botanicals that can produce color in soap, you can explore my Botanical Soap Color Index.
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Light Is One of the Biggest Causes of Fading
Exposure to light is one of the most common reasons botanical colors fade.
Sunlight contains ultraviolet radiation, which can break down many natural pigments. Over time this can cause colors to lighten or shift slightly. Even indoor lighting can contribute to fading if soap is displayed for long periods of time under bright lights. If you’ve ever noticed that the side of a soap facing a window fades more than the other side, light exposure is usually the reason.
Heat Can Also Affect Natural Soap Colors
Heat can accelerate changes in botanical pigments.
Warm environments — such as bathrooms, storage areas near heat sources, or soap stored in direct sunlight — can cause colors to fade or soften more quickly.
During the soapmaking process itself, higher temperatures can also influence how pigments develop. Once the soap has cured, however, long-term heat exposure is what tends to affect color stability the most.
Proper Storage Makes a Big Difference
In my own experience, botanical soap colors can last a very long time when stored properly.
The soaps from my book kept their colors for well over six years, and some of the original soaps from my Extracting Color from Nature Master Class still had strong color — and even some scent — more than five years after they were made.
The key was simple storage.
Here’s a short video showing the 5 year old soaps from class and here’s a look at the soaps from my book about 2 years into their storage.
Soap should be stored in a way that allows airflow while minimizing exposure to light and excessive heat. Some good options include:
- wrapping bars in paper
- storing soap in boxes
- placing them in breathable fabric bags
These methods protect the soap from light while still allowing the bars to continue curing properly.
If you’d like to learn more about working with botanical colorants and different extraction methods such as oil infusions, slurries, teas, and decoctions, you can explore the full Extracting Color from Nature Master Class.
PSA: Fading Is Not the Same as DOS
It’s important not to confuse normal color fading with Dreaded Orange Spots (DOS).
DOS appears as small orange or rust-colored spots caused by rancidity in oils. This is a completely different issue from botanical pigments slowly softening or changing color.
If you want to learn more about that problem and how to prevent it, see my article on Dreaded Orange Spots in Soap.
Live is Short… Use Your Beautiful Soap!
And here’s something I always tell people — sometimes jokingly, but it’s true.
If you make soap and you still have it sitting around six months later, you probably need to:
- make less soap
- give some soap away
- or take more showers
Soap is a consumable product, not a museum artifact meant to preserve color for centuries. The joy of natural soap colors is using them. Enjoy the beautiful bars you create, use them generously, and then make more.
Happy soaping. 🧼
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