Gelled vs Ungelled Soap – What’s the Difference?

Gelled vs Ungelled Soap - What's the Difference?
Vivid colors achieved by gelling soap –
www.BathAlchemyLab.com

I get lots of questions about a variety of soap topics.  The other day, I was asked what the differences were between gelled and ungelled soap.  They had read some confusing and misleading posts on forums about the differences, including that cure times were shortened and fragrances were stronger in gelled soap.  I realized that this may be a question that others want to know more about as well, hence the explanation on gelled vs ungelled soap.

 

Here are the facts,  which are gathered from chemists who work with testing various aspects of soapmaking, and well known industry leaders who have conducted their own experiments but not to the
standards of a chemist (in other words, the experiments are not lab quality but certainly reliable information).  In my experience, I have to agree with their conclusions.
The only differences of a gelled vs. ungelled soap:
1. It behaves differently when submersed in water for long periods – like after 18 hours (this will never matter to anyone – seriously)
2. Some FD&C dyes and micas coated in FD&C dyes will be stronger and brighter if gelled and muted if ungelled.
3. Gelled soap sometimes appears glossy while ungelled soap appears matte, but not always.
That’s it!
Some information circulating the Internet about cure times and fragrance strength is not proven and doesn’t even make sense.  Allow me to explain.

When a soap goes through a gel phase, it heats up.  Soap that is heated takes on a gelatinous appearance, hence the name.  The gel phase will hasten saponification.  Most saponification occurs in the first 24 hours while still in the mold.  The curing time is not so much waiting for the saponification process as it is waiting for the soap to become milder to the skin and to lose some of the water in the soap.

Gelled vs Ungelled Soap - What's the Difference?
LabColors tested through a partial gel phase reveal
stronger colors with gelling – from www.soapqueen.com

According to experiments conducted by Kevin Dunn, a chemist specializing in soapmaking, it appears most soaps have a rather short peak in a gel phase and the temperature typically stays below 180°F.  The only soaps that reached 180°F in his experiments during gel phase had high water content (amounts that most people would never consider using).   Now, some fragrance oils can push this temperature higher, but it is more important to note how long the temperature is sustained in the gel phase.  In the experiments, the peaks were short – 20 minutes or so in length at the top temperature.  Therefore, cure times would not be shortened as hot process soap needs a longer cooking time, according to most hot process soapmakers.  I have yet to find experiments documenting length of cook time with length of cure time.  Plus the hot process method requires you to reach a ‘fluff’ stage to know it is finished cooking, which is well past the gel phase.  Gelled soap just doesn’t heat up high enough and long enough to reach that state and warrant shorter cure times.  If you want shorter cure times, HP your soap.

As for the fragrance sticking better, there is just no evidence of this.  Logically, if your soap had a high percentage of water and you managed to get the temps up around 180°F or higher, it would probably have the opposite effect as the fragrance could theoretically burn or cook off.  However, that isn’t necessarily the case, as most soaps go through a gel phase that comes nowhere near these higher temperatures.
Some people feel that you shouldn’t allow a milk soap to gel.  This is not the case.  The gel phase would have to be much higher than 185°F, which is the temperature that can be used to scald milk (scorching it would have to be hotter).  Most gel phases do not even reach 180°F.  You would have to use lots of hot water plus soap at hot temperatures and really work to get it over that temperature.  Adding lye to the milk is the only time there is a risk of scorching.
Things that affect gel according to the experiments:
·        Size and shape of mold
·        Higher initial temps of oil and lye will cause a higher temp in the gel phase
·        Lower water in formula needs a higher temp to gel
·        Saturated fats reach a higher gel temp than unsaturated oils
·        Fragrances, essential oils, and certain additives can increase the gel temps
Recommendations:
·        If you want a non-gelling soap to go through gel, soap at higher initial temps and use more water in the recipe.
·        If you want a gelling soap to avoid the gel phase, lower the initial temps and use less water.
Please post questions and comments below.