What is "Cold Process" Soap anyhow? – Nest Soapery

What is "Cold Process" Soap anyhow?

I'll bet you've heard this term, but you may not be sure exactly what it means. I'm here to break it down for you!

When you purchase someone's hand crafted soaps, you're likely purchasing one of two kinds - 

1. Cold/Hot Process - soap created by combining raw ingredients to create a completely different product - SOAP! This product is sometimes colored and fragranced for the soap maker's design. This can be done by heating the ingredients and cooking them until they're soap (Hot method) or by giving the batter time to become soap via chemical reaction.

2. Melt and Pour - This is a soap base that can be melted down and combined with colorants and flavors in order to produce a finished product. Almost all clear handmade soaps are melt and pour. 

Now that you have a basic understanding of types of soap, let me go a bit more in depth with what Cold Process soap is...

It's not playing with fire, but it's pretty dang close!

Making soap with in the hot/cold process manner can be quite dangerous if the soap maker doesn't take precautions. There's one ingredient in particular that is quite dangerous - Lye.

Lye, caustic soda or Sodium Hydroxide, an essential ingredient in handmade soaps. Back in ye olden days, it was derived from old ashes, but nowadays, it can be found in most hardware stores, sold as drain clog remover. That's right - the same stuff that you pour down the drain when you've got a clog is what makes soap SOAP. If mishandled, lye can cause some serious burns or even blindness. Caustic fumes can be released when creating lye solution, a necessary part of soap making. 

In conjunction with various oils (coconut, olive, grapeseed, rice bran, avocado, palm, etc) the lye creates a chemical reaction called saponification, in which the fatty acids in the oils are converted into salts, or what we call soap. 

Check out a video below to see how soap is made in real time. 


Great precautions need to be taken in order to do this safely. Gloves, long sleeves and protective eye gear are essentials when working with lye. Small children and dogs need to be out of the way as well. Your soap maker is less hobbyist and more chemist than you knew!