You’ve found a bar of handmade soap at the back of a cupboard. You can’t remember when you bought it, but it looks perfectly fine. Can you still use it? Or does handmade soap have an expiry date? Well, the answer is a bit more complicated than a simple yes or no.
Handmade soap doesn’t usually spoil in the same way that food does, but nor does it last forever. And there are several things that can change as a bar gets older.
Let’s investigate.
How long does handmade soap last?
A properly formulated and cured bar of cold process soap can remain in good condition for a considerable time, particularly if it’s stored correctly. You might see people suggesting that handmade soap lasts 12 months, 18 months or even several years. But there’s no single lifespan that applies to every handmade bar.
The oils used in the recipe, the amount of superfat, the fragrance, any additional ingredients and the way the soap is stored can all make a difference.
Some oils are more susceptible to oxidation than others, which means soaps containing higher proportions of those oils may be more prone to developing rancidity over time. So, as with my previous post about how long a bar lasts in use, the answer is largely: it depends.
I know, helpful. 😂
Does the fragrance disappear?
One of the first things you might notice with an older bar is that its fragrance isn’t quite as strong as it used to be.
Essential oils contain volatile aromatic compounds, which can gradually evaporate or change over time. Fragrance oils can fade too, although the extent depends on the particular fragrance. Some scents are more persistent than others. Certain citrus notes, for example, can be particularly prone to fading, while some heavier, woody or spicy fragrances can remain noticeable for much longer.
That’s why a bar that’s been sitting in a cupboard for a couple of years might smell considerably less exciting than it did when you bought it. There may not be anything wrong with the soap itself. It may simply have lost some of its original fragrance. That might be disappointing if you were looking forward to a particularly lovely-smelling shower, but not necessarily a disaster.
Can soap actually go rancid?
Yes, it can, and this is where the chemistry gets interesting (again!).
If you’ve read my Blogtober post about superfatting, you’ll know that I deliberately formulate my soap recipes so that a small proportion of oils remains unsaponified in the finished bar. Those oils, along with some of the fatty components within the soap itself, can undergo oxidation over time.
Oxidation is a chemical reaction involving oxygen, and it can eventually cause oils and fats to become rancid.
You may have encountered rancidity in food before, perhaps with an old bottle of cooking oil or a packet of nuts that’s been lurking in the cupboard for too long. Not a particularly appetising smell. Something similar can happen in soap.
The dreaded orange spots
Among soapmakers, there’s a rather dramatic-sounding phenomenon known as DOS, short for Dreaded Orange Spots.
And yes, we really do call them that. They’re patches of orange, yellow or brown discolouration that can develop on a bar, often associated with oxidation and rancidity. Sometimes they’re accompanied by an unpleasant smell, rather like stale oil or old crayons.
Not every orange mark on soap is DOS, of course. Some soaps contain deliberately coloured ingredients or fragrances that naturally cause discolouration. But if an old bar develops unexpected orange spots and starts smelling decidedly peculiar, rancidity is a strong possibility.
And at that point, I might retire it from bathroom duties. It’s not harmful to use but there are plenty of other bars waiting for their opportunity.
Does soap get better with age?
Now here’s an interesting little twist. If you’ve read my post about curing, you’ll know that freshly made cold process soap needs time to develop into a firm, long-lasting bar. During curing, excess water evaporates and the soap’s internal structure continues to develop.
So a bar that’s been properly stored for longer than its normal curing period will probably become harder and last longer in use. There’s a good reason I recommend storing your bars in your underwear drawer (see below) – our forebears knew what they were doing! But there’s a difference between allowing soap to mature and keeping it indefinitely.
Eventually, the benefits of further ageing may be outweighed by fragrance fading, oxidation or other changes. An older bar isn’t automatically a better bar, even if it is wonderfully hard.
How should I store unused soap?
If you’ve bought several bars and want to keep some for later, a little care with storage can make a real difference. The most important things are to keep them somewhere cool, dry and away from direct sunlight Heat and light can speed up the deterioration of certain oils, fragrances and colourants, while excess moisture can affect the condition of the bars.
A dry cupboard or drawer is usually a much better place than a permanently steamy bathroom.
I’d also avoid sealing damp soap inside an airtight container. You don’t want to trap moisture against the bars.
And if you’re keeping several different fragrances together, be aware that strong scents can sometimes transfer between bars. Nobody wants their delicate floral soap unexpectedly smelling of peppermint. Unless, of course, that’s your thing.
What about best-before dates?
This is where things become a little more technical.
Soap sold as a cosmetic product in the UK is subject to cosmetic safety and labelling regulations, which include requirements relating to product durability.
Depending on the assessed shelf life and characteristics of the product, this may involve a minimum durability date or other appropriate labelling information. For cosmetics with a minimum durability of more than 30 months, a best-before date isn’t automatically required, although other rules may apply.
So there’s no universal expiry date that every handmade soapmaker can simply put on every bar. The appropriate durability information depends on the particular product and its safety assessment.
And it’s worth remembering that a best-before date isn’t necessarily the same as a sudden point at which a product becomes dangerous. It relates to how long the product is expected to remain suitable and perform as intended when stored under the specified conditions.
So can I use an old bar of soap?
If you’ve discovered an old bar in the cupboard, I’d start by checking any date or storage information on the packaging.
Then have a good look at it. Has the fragrance faded? Has the colour changed? Are there unexpected spots, a strange smell or any other obvious signs of deterioration? A bar that’s simply lost a little fragrance is a different matter from one that’s developed rancidity.
If the soap is within its stated period of use, has been stored properly and appears to be in good condition, there’s generally no reason to worry just because it isn’t brand new.
But if it’s well beyond its stated durability, smells rancid or shows signs of deterioration, I wouldn’t recommend using it. And if you’re unsure, it’s better to err on the side of caution.
My advice? Enjoy your soap!
I know it’s tempting to save particularly beautiful bars for a special occasion, especially when they smell wonderful and have lovely swirls. But soap is made to be used. While proper storage can help preserve it, keeping a bar hidden away for years means you may miss out on enjoying it at its best.
So by all means buy a few bars to keep in reserve, especially if there’s a limited-edition fragrance you love.
Just don’t feel you have to save them indefinitely. That lovely soap deserves to be used, and an ordinary Tuesday is a perfectly good occasion.
Vicki x