What Is Glycerin Rivers In Cold Process Soap?

Oh the dreaded glycerin rivers in cold process soap making.

First things first. Glycerin is a natural by-product that happens when soap is made. Glycerin itself, can effect not just the look of soap. There is potential, (if it were to congeal more in one area of the soap), to effect texture as well. Thus, making the soap feel soft in a specific area.


preventing glycerin rivers in cold process soap making


With large scale commercially made soap, glycerin is actually separated out during soap making to sell to manufactures, food companies and so on, as a commodity. 

However, glycerin is wonderfully moisturizing for the skin. One of the great things about homemade soap is that when it’s made, glycerin is distributed throughout each bar of soap. 

Does everyday store bought soap tend to leave your skin feeling dried out? In fact, this may be one of those reasons.


What are Glycerin Rivers & Why do they Occur?

One of the more common issues, besides discoloration and acceleration in cold process soap making, is that of glycerin rivers.

Glycerin rivers do not necessarily effect the performance of your soap, however it can severally alter it, aesthetically.  

Some refer to glycerin rivers as crackling or glycerin separation as well. True glycerin rivers are most often caused from temperature issues. For example, overheating and cooling issues during saponification. 

They can commonly be more pronounced in recipes that include certain colorants as well, especially with pigments. This is due to the pigments densities compared to colorants, such as mica’s. 

One of the more common pigments is titanium dioxide. In fact, some people refer to glycerin rivers as “titanium dioxide rivers” as this white substance makes them more visible.


titanium dioxide rivers in cold process soaping


Titanium Dioxide:

Titanium dioxide is a white pigment. Oftentimes, it’s used to soften colors to help keep a soap a lighter shade when using a fragrance that discolors. However, using it can encourage glycerin rivers throughout your soap or in certain areas. 

Some titanium dioxide pigments are water soluble. This is another important thing to keep in mind. In our experience, excess water or liquids in your soap can also contribute to glycerin rivers, because of overheating. If you indeed dissolve your titanium dioxide in water, it’s important to keep in mind how much additional water is going into your batter (recipe). You can help minimize this issue by doing a water discount in your recipe


Premix Colorants:

Having said that, many soap makers “pre-mix” there colorants. Why?

When premixed in a lightweight oil, pigments, micas and other powdered colorants will often distribute more effectively, and more evenly in your batter. Consequently, helping to avoid overmixing your batter and accelerating trace. Even a simple stir with a spatula can incorporate some of the colors, if mixed beforehand. 


Related Article: Working with Colorants in Cold Process Soap Making: How to Premix


While on the subject of excess liquids, certain liquids themselves can increase the likelihood of glycerin rivers. This includes liquids that have high sugar content. For example;

  • milks,
  • beers
  • or fruit juices. 

Another potential culprit of glycerin rivers, is the fragrance that you chose. Fragrances higher in floral notes, tend to be more prone to causing glycerin rivers.

If you’re a soaper that gels your soap or forces gel, this can increase the likelihood of glycerin rivers happening due to the potential for overheating. 


How to Prevent Glycerin Rivers


how to prevent glycerin rivers in cp soap making


The best way to avoid glycerin rivers is by not allowing your soap to overheat. You may try trying a water discount into your soap recipe. This may also entail keeping a closer eye on your soaps, once you’ve insulated your soap batch!


Mix Colorants: 

Mix your colorants well before using them in your recipe. Usually this is done in a lightweight oil. It’s better to disperse titanium dioxide in a lightweight oil (in our opinion), then in water. 


Fragrance Selection (testing):

Make sure to always research you fragrance choices. Are there performance notes? Are their customer or other soaper reviews? Ask the company themselves with a simple email if no performance notes are given.


Lower Temperature Soaping:

As mentioned before, overheating can lead to glycerin rivers. Try soaping at a lower temperature. We soap between 85-100 degrees F and very rarely ever run into glycerin rivers.


Different Mold: 

Certain molds (like wood) insulate soap better then others, meaning they could heat up faster then soaps set to cure in other materials. Try individual molds. These will heat up much less then a large soap loaf mold. 

Test. Test. More Testing!


Finial Thoughts!

Hopefully some of these tips will help you avoid glycerin rivers in your cold process soaps. Some people actually don’t mind glycerin rivers and believe they add another dimension to soaps!

Please be sure to leave a comment on a time when you ran into glycerin rivers. What happened? How did you rectify the issue on the next batch? This is a great way to help other soapers avoid similar mistakes!