Soap molecules aligning in a hot process

The very fine strands of soap molecules that appear at the end of our soap-making process illustrate a small, but important difference in quality between "hot process" and "cold process" bar soaps.  

Fine strands of soap molecules

These strands of soap look like hairs they are so fine and they appear in the final stage of the process when the soap molecules are aligned and connected.

Soap manufacturing is based on a process called saponification - a chemical reaction that brings together oil and sodium hydroxide molecules to make a new and different molecule that is soap. 

In cold process soap making the saponification reaction happens slowly over many hours, even days at temperatures cooler than 50 Celsius. 

In hot process soap making the temperature is much hotter around 90 Celsius and the same ingredients yield the same quantity of soap in a much shorter time - sometimes less than an hour.

At these higher temperatures the soap molecules align themselves much more tightly and the bars are less able to absorb water and soften.  In the cold process method the soap molecules are arranged more loosely and it is easier for water to penetrate the matrix of soap molecules and the bars can soften.

In our experience the hot process makes a much better bar and these thin strands of soap molecules, aligned so tightly together they form hairs, are an indicator of the quality.