My first experience with the traditional cold process method of soap making happened in 2012. I had a bit of time off work and being clinically unable to sit still, I pestered a family friend (a soap maker) to teach me how to make soap. And that’s all I did for the next few months. Testing out fragrances, recipes, making chunks of soap, handing them to my friends, making black soap, making white soap, and for a lark, calling my “brand” at that time - Skunk - like the animal, because my soap was black and white but it smelled better. Haha.

But the chemistry of it all kept me glued to the process. It is so interesting and dates back thousands of years, when soap was a rarity and not something available to everyone.

Now, walk into any supermarket and you'll find shelves full of soap bars. Walk into an independent shop and you'll find some more. But they're not the same product.

Independent stores typically stock cold process soap. And the difference between these bars and what you find in supermarkets comes down to how they're made.

WHAT IS COLD PROCESS SOAP

Cold process soap is made by combining oils with lye (sodium hydroxide), which triggers a chemical reaction called saponification that turns them into two things: soap and glycerin.

"Cold process" refers to the fact that the soapmaker isn't adding external heat. The reaction between the oils and lye generates its own heat.

The mixture is poured into moulds, then left to cure or rest for 4 to 6 weeks while the reaction finishes. The water evaporates out during the curing period, leaving the bar harder and drier.

How long the soap cures for makes a difference to the finished bar's quality. A bar that's had the full cure time is noticeably firmer and produces a better lather. One pulled too early feels softer, won't last as long, and won't perform as well in the shower. (link to "won't last as long" to shelf life article). All Skunk bars cure for 6 weeks.

Mass-market soap manufacturers sometimes remove the glycerin from the final soap bar. In cold process soap, the glycerin stays. That makes a big difference to how cold process soap works for your skin.

WHY THE GLYCERIN THAT STAYS IN COLD PROCESS SOAP MATTERS FOR YOUR SKIN

Very simply - glycerin draws moisture to the skin and helps maintain the skin's natural protective barrier, leaving it feeling more supple rather than tight or dry after washing. It's why many people notice their skin feels softer after a shower. This in itself makes a case for natural, hand made soap.

It's also been shown to help restore hydration to skin that's been irritated by harsh detergents like sodium lauryl sulphate (SLS) that are commonly found in commercial soap. 

Who cold process soap suits — and who should be cautious

Cold process soap tends to work well for people with dry or sensitive skin, including those prone to eczema or psoriasis. The glycerin, combined with nourishing oils like shea butter and coconut oil, leaves skin more comfortable after washing. It's also free from synthetic additives common in commercial bars such as SLS, synthetic fragrances, or parabens. This reduces the chance of irritation for people who react to those ingredients.

That said, it's not the right choice for everyone. Some people find any bar soap drying, and cold process may still not suit very sensitive or reactive skin even though it's gentler than most commercial options. Essential oils and botanical additives can trigger reactions too, so it's worth doing a patch test before full use no matter what your skin type. And also worth looking for soap bars that have no essential oils or fragrances.

If you're dealing with a skin condition, it's best to consult a dermatologist before trying any new skincare product, including a cold process soap bar.

It's also typically more expensive than supermarket soap. You're paying for real ingredients, a longer production process, and a bar that's kinder to your skin, which is why many people find it worth it. Less chemicals, better skin.

How to tell if you're buying genuine cold process soap

If you want to make sure you're getting the real stuff, here's what to look for (link to how to choose a shea butter soap bar when it's published) when buying a cold process soap bar:

• Genuine cold process soap will list lye (sodium hydroxide) or its saponified equivalent (sodium olivate for saponified olive oil) on the label

• It should have a clearly listed ingredients deck on the packaging, and a cure or batch date

Price is a useful signal. If a bar is priced like a supermarket soap, it probably isn't what you're looking for. The ingredients and production time mean a genuine cold process costs more to make. 

Try cold process soap for yourself

If you're ready to make the switch, our (Un)Adulterated bar is a good place to start. It contains olive oil, shea butter, coconut oil, and a touch of rosemary essential oil. Made using the cold process method, it's cured for 6 weeks and free from sulphates, artificial colours, and preservatives. It was one of the first bars of soap I ever made with Skunk and happens to be my favourite. The very mild hint of rosemary in the bar ends up making you feel squeaky clean.