Extended saponification

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veron

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Hi,

I have been controlling the saponification without going above 70 °C to avoid the gel state. I have a blend that doesn't have a hard trace point. I was wondering how long I could keep it at 60-70°C to ensure almost all of the sodium hydroxide is consumed. Has anyone tried that? This has worked for me to add temperature sensitive components, but I want to make sure with some data or recommendation of how long I can leave it for most of the sodium hydroxide to react.

So far I don't wait more than 15 minutes after trace point for the temperature to drop a little and pour it into the mold.

One of my concerns is that not all the sodium hydroxide has reacted, but after 3 weeks there is no problem (zap test).

Thanks :)
 
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I was wondering how long I could keep it at 60-70°C to ensure almost all of the sodium hydroxide is consumed. Has anyone tried that?
Yes. This is called hot process.
Regular hot process (unlike HTHP = high-temperature hot process, i. e. deliberate volcanoing), can be conveniently carried out not boiling hot, but well in your desired temperature range. However, I can hardly believe that there is any way to prevent gel phase at these temperatures, even with the most exotic oil blends. How would you tell it is not gelled? I'm also unaware of reasons why it is specifically gel phase that would be detrimental for some additives (how ungelled soap at some temperature should be less harsh to temperature-sensitive additives than gelled soap).

With a well-behaved oil blend and a good dose of sodium lactate, you can make finished HP batter (fully gelled, with zero excess lye left!) fluid enough to stir in any additive you like, at intermediate temperatures, and immediately pour into the mould(s), for unmoulding (and zap neutrality) just after cooling down.


The ultimately gentle way to incorporate sensitive additives into soap, is using melt&pour soap.
 

veron

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Thanks, ResolvableOwl, I really didn't know the difference between hot process and HTHP, I thought it was the same thing.

Until now, when I saponified at a higher temperature, there is a point where the mixture gels or increases viscosity a lot, at which point the temperature increases faster and becomes very difficult to handle. In fact, just for testing, I added cetyl alcohol a little over 5% and this happened much faster xD. When I saponify at 60-70 °C the mixture does not go through that point and when I put it in the mold the mixture is very well defined.

Sure, I imagine if I keep it long enough between that temperature the mixture will gel, but I'm going to try to understand it, as long as it has the necessary fluidity at a reasonable temperature, I have no problem.

Regarding sodium lactate, I have never used it, I thought it was only to increase the hardness of the soap in the end, would it help me by maintaining the fluidity of the mixture?
 

DeeAnna

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@veron -- If a sodium soap is heated to 140-160 F / 60-70 C (or higher) and it can be stirred, even with difficulty, then, by definition, the soap is in the gel phase.

What we small-scale soap makers call "gel" is simply a paste-like semi-liquid state that soap can have. "Gel" lies somewhere between a non-stirrable solid soap and a fully liquid soap solution (what's called an isotropic solution.)

The changes in viscosity you're observing are not related to the soap being "in gel" versus the soap not being "in gel". These changes are created by the various stages that soap can have when it's within the gel phase. These stages are related to the water content of the soap as well as its temperature. Some stages of gel are highly viscous and difficult to stir (middle soap stage) and other stages are more fluid and easier to stir (neat soap stage).

Adding other non-soap ingredients (salts such as sodium lactate or the cetyl alcohol you tried) will affect the behavior of the soap when it's in this paste-like state by altering how the soap molecules interact with each other as well as with the other molecules and ions in the mixture.
 
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TheGecko

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I have been controlling the saponification.....

You really can't control 'saponification'. As soon as you add your lye to your fats, the process begins. A good example of this can be found when making your Lye Solution with 100% milk and when putting your milk soap in the freezer to keep it from overheating and/or gelling.
 

veron

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@DeeAnna I have been using 20-25% water by weight of oils. Thanks for your answer. From what I understand, depending on the temperature and others components, they can predispose one stage over the other.

When I raise the concentration of cetyl alcohol, the saponification accelerates as well as the temperature, reaching that stage that you tell me, middle soap stage. I have worked at lower concentrations and saponification occurs quietly and there is no significant increase in temperature.

In the future, I am going to do different tests, also with sodium lactate.
 

veron

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Yesterday I tried, I added sodium lactate and the mixture was fluid enough after an hour of keeping it between 60-62°C (consistency or fluidity like shea butter). I waited below 50 °C stirring with the spatula to lower the temperature and added the essences.
I increased the water a bit too.
I think that, seeing the mixture, I will never be able to obtain the spectacular fluidity at the trace point, but the paste-type dough allows me to add the components and transfer the dough to the mold.

Thank you very much for your answers.
 
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Unless you are using the exact same amount of the exact same oils each time, you will get more consistent results if you use a lye percentage instead of water as percent of oils. Using the latter, your superfat (aka lye discount) is going to fluctuate based on what oils you use, and how much of each. For a fluid batter, I like to HP with a 25% lye solution, or 3:1 water:lye ratio.

Also, hopefully you are aware that your soap will finish saponifying all on its own, even if you don't get it 100% zap-free during the cook. You can basically stop and put the batter into the mold anywhere along the spectrum between full cold process (with zero additional heat applied), and HTHP (where the heat is maximized to speed up the process). It will still become soap, and if your recipe is correct, it will be zap free. How long it takes to become zap-free is another story. :)
 

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