What Is Cold Process Soap? A Beginner's Guide

So...What Is Cold Process Soap?

Cold process soap is made the old-fashioned way, totally from scratch, by mixing natural oils or butters with a lye solution (aka sodium hydroxide and water). When you combine the two, science takes over: they go through a chemical reaction called saponification, which turns the oils into soap and creates glycerin (more on that in a sec).

It's called "cold" process because there's no extra heat involved. Instead, the soap batter is poured into molds and cured at room temperature for 4-6 weeks. Yep, it takes patience, but the result is totally worth it.

How Cold Process Soap Is Made (Quick Breakdown)

Below is a simplified version of the process. Stay tuned, we'll be diving deeper into the details in an upcoming post!

1. Mix lye and water

2. Melt (if needed) and blend oils

3. Combine the oils and lye mixture

4. Blend until "trace" - when the mixture thickens like pudding

5. Add scent, color, and any fun extras (like botanicals, clays, or exfoiliants)

6. Pour into molds and let it rest for 24-48 hours

7. Unmold, slice into bars, then cure for 4-6 weeks to harden

The result? A solid, skin-loving bar that's ready to lather and last.

Cold Process vs. Other Soapmaking Methods

Not all soaps are created equal. Here's how cold process compares to other common methods:

Melt and Pour Soap

• Premade base is melted and customized

• Super fast, but you don't get full control over ingredients

• Great for beginners or decorative designs

• Usually lacks naturally produce glycerin

  
  

Cold Process Soap

• Made from scratch with raw ingredients

• Full control over what goes in

• Naturally rich in glycerin (skin loves this)

• Takes time, but the end result is chef's kiss

  
  

Commercial Soap (aka Syndet Bars)

• Mass-produced, often detergent-based

• Can contain synthetic foaming agents, preservatives, and fillers

• Can leave your skin feeling dry or stripped

• Technically not even real soap in may cases

Why Glycerin Matters in Soap

Okay, we keep mentioning glycerin, which sounds great, but when even is it?

One of the biggest benefits of cold process soap is that it naturally produces glycerin during the saponification process. No need to add it in later or fake it with synthetic moisturizers.

Glycerin is a humectant, which means it draws moisture from the air and into your skin. This helps keep your skin soft, hydrated, and healthy. In other words, it's kinda of a big deal for your skin barrier.

Here's the kicker, in many commercial soaps, glycerin is actually removed and sold off to make lotions and creams. That's part of why those bars can leave your skin feeling tight or dry. But with cold process soap, the glycerin stays in, right where your skin needs it.

So when we say our bars are naturally glycerin-rich, we mean it. It's in there, doing its thing every time you lather up.

Common Questions (We Got You, Remember?)

Is cold process soap safe to use?
Totally! Lye is essential in the beginning, but it's completely used up during saponification. By the time it's cured, there's no lye left, just real soap.

Why does it take weeks to cure?
Curing lets water evaporate, which hardens the bar, makes it milder, and helps it last longer in the shower. Worth the wait, trust us.

Does it lather well?
Heck yes! Our cold process soap has a rich, creamy lather thanks to the combination of natural oils - no synthetic formers required.

That's the Soap Scoop

Cold process soap is kind of a soap geek's dream. It's where chemistry, creativity, and self-care all come together. It takes more time and effort, but the payoff is a bar that's gentle, effective, and totally skin-friendly.

At Real Soap, we're all about that slow-made, thoughtful approach. Whether you're new to handmade soap or deep into ingredient labels, we're glad you're here learning with us.

Want More Soap Science and Behind-the-Scenes?

Stick around, we're sharing more about ingredients, sustainability tips, and what really makes a good bar good. Got a question about something and would like to learn more? Send it our way or come hang out with us on Instagram for soap cutting videos, behind-the-scenes peeks, and general bubbly goodness.