That Gel Thing

To gel or not to gel

I'm pretty sure that every cold process soapmaker has, at one point or another, wondered about the gel conundrum. Should I gel my soap? Should I not? What's best for the soap? For my customers? For Captain Kirk? Does it really matter anyway? Can I let the soap decide what it wants to do? And on it goes.

So, lets explore this gelling phenomenon. 

When the soap batter is mixed and poured into the mold, it's not yet soap. While it looks cozy in its wooden (or plastic, or cardboard/silicone/PVC/Kryptonite) bed, it is very busy undergoing saponification, a process that will take many hours or even days.

Soap just after it's been poured in the mold

Soap in gel phase

Soap after gel

  During this time, the chemical reaction between the oils and the lye creates heat which builds up, starting at the centre of the batter. If the soap is encouraged to hold on to this heat - more on this later - it spreads outward, and if the temperature gets high enough, the entire soap becomes darker and slightly translucent (like Vaseline). The soap is now in the gel phase. And it is hot! If you've never experienced this before, it can be a bit freaky!


When it has done "its thing" - it may take hours - the soap will cool down and its colour will lighten up. It may return to its original colour - or close to it - but often will remain darker than when it was poured into the mold. It will also retain some of its translucence instead of becoming as opaque as it was before the gel.

So, is that good? Bad? Atrocious? A reason to throw a party?

Although both gelled and ungelled soaps produce fine bars that are beautiful and luxurious, there are pros and cons to this process.

On the one hand, a gelled soap set ups a bit faster, is slightly harder and may last a bit longer than its ungelled counterpart. Also, the colour of the soap will often deepen when the soap is gelled. Depending on the type of colorant used, this can be a desirable effect.

On the other hand, if you're making milk soap, or soap that contains honey, or any type of sugar (molasses, syrups, etc), the heat of the gelling process will caramelize the sugar in the milk or honey and will give the soap a brown hue. The texture of a gelled soap is often not as smooth as that of an ungelled bar. On top of that, if the soap gets hot enough, the glycerin - a product of saponification - can sometimes separate and cause veins or a crackly effect, one that is especially visible if your batter also contains titanium dioxide.


All this being said, it comes down to preference. There's no requirement that a soap be gelled or not gelled. It's really what you like, and sometimes, what the soap likes. The only thing you don't really want is a partial gel. That's when the gel phase stops before reaching the edges and corners of the soap log, resulting in a dark "middle".  The soap is fine to use, but doesn't look all that attractive.

How do you encourage your soap to gel properly?

• Use large loaf molds rather than individual molds. The larger the amount of soap within the mold, the more it will retain its heat.
• Wooden molds tend to retain heat better than cardboard or some plastics.
• Insulate your mold by putting a lid on the top. This can be a piece of wood, cardboard, or even plastic wrap. Then, cover the whole thing with towels or a blanket.
• Some soapers use a heating pad to gently keep the soap warm. Make sure the settings are such that it won't cause the soap to overheat or burn your house down. 
• Consider oven processing your soap. I've never done this method myself, but there are many sites and blogs which describe it well.

The temperature at which you soap may also influence whether or not your soap reaches the gel stage. If you soap at a higher temperature, then the mixture is already that much closer to gelling temperature. Of course, that is no guarantee that this alone will make gel happen, but when used with the other measures described above, that's one more step in the gel direction.

Be careful, though, if you're using milk/honey additives as these tend to make the soap mixture heat up more, so a lower soaping temperature in these cases is warranted. And, as mentioned previously, gelling is best avoided altogether here. (Mind you, there are people who gel their milk soaps and are happy with the results; again it's that preference thing.)

OK, so you DON'T want to gel your soap?

• Use small individual molds if possible.
• Place the soap in the refrigerator for several hours after pouring it into the mold. Some people even put it in the freezer.
• If the refrigerator/freezer is not an option, use a fan to circulate the air over the surface of the soap. This will help to dissipate the heat and cool it down.

If you're still not sure about this whole gelling thing, it's often worth making a batch of soap and dividing it into two parts. You can gel one part and not gel the other, and you can then easily compare the two and decide which one you like best.

Happy gelling, or not....