Degrees of gelling

[Rsapienza]

This probably sounds kind of wacky, but are there different degrees of gel phase? I have made the same exact recipe, same temps, but different molds. Fresh out of the mold, the end result seems so very different, almost like 1 gelled "harder" than the other. Hope that makes sense.

 

[jcandleattic]

This probably sounds kind of wacky, but are there different degrees of gel phase? I have made the same exact recipe, same temps, but different molds. Fresh out of the mold, the end result seems so very different, almost like 1 gelled "harder" than the other. Hope that makes sense.

Yes, you can have partial gel, full gel, no gel, over-heating, etc.,
In different molds you very well can have different results - different molds will conduct heat differently so the gel will not necessarily be the same, even if it's the same type of mold.
Even the same mold, in the same place, with the same recipe can gel differently made at 2 different times.

 

[Rsapienza]

Yes, you can have partial gel, full gel, no gel, over-heating, etc.,
In different molds you very well can have different results - different molds will conduct heat differently so the gel will not necessarily be the same, even if it's the same type of mold.
Even the same mold, in the same place, with the same recipe can gel differently made at 2 different times.

I don't mean the different stages of gel. Both soaps had full gel. I guess I didn't realize that different temps (all in gel range) would create such different soaps (upon unmolding, that is). Maybe they will end up being identical after the cure. Who knows?

 

[Mobjack Bay]

Could it be a matter of how long it stays in gel phase? I think I recall reading in Kevin Dunn's book that the alignment of the molecules changes during gel, but I'm traveling and can't check. I'm thinking that neatly aligned soap molecules could make a harder soap than more randomly aligned molecules. Almost a guess on my part...

 

[Rsapienza]

Could it be a matter of how long it stays in gel phase? I think I recall reading in Kevin Dunn's book that the alignment of the molecules changes during gel, but I'm traveling and can't check. I'm thinking that neatly aligned soap molecules could make a harder soap than more randomly aligned molecules. Almost a guess on my part...

That would definitely explain the difference between the two.

 

[DeeAnna]

I agree the length of time in gel can affect the texture, translucency, and hardness of the soap after it cools and solidifies.

I'm not entirely convinced that soap has to actually transition into the gel phase to get the benefit of these changes. My thinking (just opinion here, not fact) is that soap kept just below its gel temp for an hour or so will show many of the same changes as soap that actually goes into a full gel.

These changes due to heating do not have to happen during saponification. You can warm a fully saponified soap and observe the same shift in hardness, translucency, and texture. SMF member Saponista and I have both experimented with "rescue oven processing" methods that force these changes to happen in soap after it's saponified.

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There is another aspect of soap that I don't think people know much about. Soap in the gel phase can exist in a number of physical forms depending on the particular combination of fatty acids, water content, and temperature.

When water is liquid ... it's pretty much a simple plain liquid anywhere from just above freezing to just below boiling. Simplifying a bit, water doesn't change its density, viscosity, or visual appearance much over this entire temperature range.

When soap is in the physical form we call "gel" it can exist in a number of liquidy/pasty forms that are obviously quite different.

If you've ever made liquid soap or hot process bar soap, you probably know that hot gelled soap can range in consistency from a stiff dough that is hard to stir to a gluey "vaseline" material that is easier to stir.

The dough and the vaseline states are both examples of gel phase, but they have different consistencies based on the temperature and water content. The temps and water contents at which one soap will be doughy vs vaseline-y will vary depending on the fatty acids in that particular soap. Sometimes it doesn't take much of a change in temp or water content to shift the consistency of the soap gel from dough to vaseline.

I don't know this for certain, but it seems reasonable to think the type of gel that the soap transitions into will also affect the consistency of the soap after it solidifies.