Understanding Gel Phase in Cold Process Soap

A practical guide for thoughtful soapmakers

If you’ve ever unmolded a loaf of cold process soap and noticed a darker circle in the center, you’ve likely encountered the gel phase. Whether you’re a new maker or refining your craft, understanding the gel phase helps you intentionally control your final bar from color to texture to cure time.

Let’s break it down simply.

What Is Gel Phase?

The gel phase happens only in cold process soap after your soap has been poured into the mold.

As saponification begins (the chemical reaction between oils and lye), heat is naturally produced. If the internal temperature of your soap rises high enough, the soap temporarily becomes a translucent, jelly-like consistency inside the mold. This is called gel phase.

You won’t usually see it happening, but you’ll notice the effects once the soap is cut.

Is Gel Phase a Good Thing?

It can be depending on your goals.

Allowing your soap to fully gel has two primary benefits:

1. Brighter Colors

The gel phase intensifies colorants. This is especially helpful when using:

• Natural clays

• Botanicals

• Herbal infusions

These ingredients often produce softer, earthy tones. Gel phase helps deepen and brighten them.

2. Faster, Easier Unmolding

Fully gelled soap typically firms up more quickly, which makes it easier to unmold and cut cleanly.

If you want to encourage the gel phase, you can:

• Insulate your mold with a towel

• Use a wooden mold

• Keep your soap in a warmer environment

Insulation helps retain heat so the soap reaches gel temperature throughout the loaf.

What Is Partial Gel?

Partial gel happens when the center of the soap gets hot enough to gel, but the outer edges do not.

The result?
A darker circle in the middle of your bar.

While completely safe to use, the partial gel creates an uneven appearance. For some designs, that may not be desirable.

How to Prevent Gel Phase

Sometimes you don’t want gel phase, especially if you’re aiming for:

• A soft, muted color palette

• A creamy white finish

• Milk or honey soaps that tend to overheat

Here are practical ways to prevent gel:

✔ Do Not Insulate

Cover your mold with a lid, but don’t wrap it in towels.

✔ Avoid Stacking Molds

Stacking traps heats and increases internal temperature.

✔ Work at Lower Temperatures

Soap with oils and lye solution between 26–32°C (80–90°F).

✔ Avoid Heavy Water Reduction

Less water means a faster, hotter reaction.

✔ Refrigerate the Soap

Place your freshly poured mold in the refrigerator for several hours to keep temperatures low.

Soaps That Overheat Easily

Some recipes naturally run hotter and are more prone to unwanted gel or overheating:

• Milk soaps

• Honey soaps

• Fruit or vegetable purees

• High sugar recipes

These benefit greatly from cooler soaping temperatures and refrigeration.

Final Thoughts

Gel phase isn’t “right” or “wrong.” It’s simply a tool.

At The Makers Table, we intentionally choose whether to gel or prevent gel depending on the recipe and the aesthetic we’re after. Understanding your ingredients and how they behave gives you control, and control leads to consistency.

Cold process soapmaking is both science and art. When you understand the science, your art becomes more refined.

If you’re just beginning your soapmaking journey, don’t be discouraged by partial gel or temperature surprises. Every batch teaches you something, and every loaf brings you closer to mastery.

The Makers Table