What Is Gel Phase?

There are so many ways to customize cold process soap, even after you pour it into the mold. One of those methods is called gel phase.

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What is gel phase?
It’s a part of the saponification process where the soap gets hot - sometimes up to 180° F. In the mold, the soap can look dark and slightly translucent. You may not be able to see that if it’s only gelling in the middle though.

What causes gel phase?
High temperatures. That can be from hotter oils and lye, or if the soap is stored in a hot room. Certain ingredients can also cause the soap to heat up, even at cooler temperatures. That includes anything with natural sugars like milk, alcohol, honey, or fruit.

What are the benefits of gel phase?
It really helps the colors pop in cold process soap, especially if you’re using natural options. It also gives the bars a slightly shiny look. Another advantage is timing - you can unmold gelled soap more quickly.

What are the drawbacks of gel phase?
If your recipe does contain natural sugar and goes through gel phase, it can scorch. That may just mean discoloration, but extreme heat can cause holes in the soap called tunnels. It can also make soap frosting to lose its shape.

If you prefer a matte or pastel-colored soap, we recommend skipping gel phase.

How do I promote gel phase?
Mix your lye water and oils when they’re warmer - between 100-120° F. Once the soap is in the mold, you can place it on a heating pad set to medium for 30 minutes, or cover it with a piece of cardboard and a blanket. 

You can also place it in an oven set to 170° F for one hour, then turn the heat off and leave it overnight. Just make sure your mold and the lining are heat safe.

Those steps may not be necessary in the summer, or if you’re making soap in a warm room. Prepare to adjust as needed, and check the soap frequently to make sure it’s not overheating.

How do I prevent gel phase?
The exact opposite of the steps above! Have your lye and oil temperatures around 70-100° F. When the soap is in the mold, place it in the freezer overnight. You can also place it somewhere cool like a garage or basement.

It’s that easy! Find cold process soap making projects here.