High-palmitic vs. high-stearic, once again

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ResolvableOwl

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This is kind of a follow-up to this post/discussion initiated by @Orla that didn't go out of my head … until I would make my own hands dirty. :rolleyes:

Short recap: Palmitic and stearic acids are most often mentioned in one breath (“hardness”, “longevity”, “creamy lather”, “solubility”, “stearic spots”…). Still, the two acids are not identical. How far can you safely swap one for the other, and which differences are to consider? Is japan wax or hydrogenated vegetable oils (and/or a blend of both) the last word in making hard, long-lasting no-palm soaps without the need for fancy butters?

Many hard oils/butters and most recipes contain both acids in a somewhat balanced ratio, and the vote with the feet corroborates this. P:S is most often around 1:1 to 2:1 – to little surprise: in most recipes palm, lard, tallow, cocoa butter, butter blends, and/or rice bran oil have a finger in the pie.

But what are we missing when we stay within this comfort zone of well-proven recipes?

There's a way to find out. Roughly orienting on Orla's efforts, I played around with soap calculators and came up with the following two literally eccentric recipes:
P: 33% rice bran oil, 33% HO sunflower, 25% Japan wax
S: 63% cupuaçu butter, 21% HL sunflower, 7% hydrogenated canola wax

Each also contains 9% palm kernel oil as a lauric oil, as well as ROE. 6% lye discount; dual lye with 8% NaOH swapped by KOH (to compensate the missing castor oil/increase solubility/reduce castile slime).

Of each batter, I poured two thirds into a mould, and mixed the remainders to make a third bar of the same size. CPOP time!

Some process remarks: Japan wax has a strong tendency to evoke false trace (particularly at this high addition rate) if handled just a few degrees too cool (note to myself: water bath next time). Contrary, the cupuaçu batter was “too well-behaved” and traced so slowly that the emulsion sedimented. I noticed after half an hour and gave it a mix; now they're all three sitting in the oven, experiencing a thorough gel phase.

With the obvious P/S exception, the recipes are fine-tuned to be as similar as possible. About 40% oleic and 13% poly-unsaturated. All the property numbers virtually identical, and INS/iodine as close as imaginable. Since the molecule chains of palmitic acid are shorter than stearic, the P soap has a higher saponification value, hence it contains more water and alkali %ppo. (This is inevitable, unless I had summoned some black magic with esoteric acids like palmitoleic, arachidic or erucic.)

The P soap has a P:S ratio of 7.2:1, while the S recipe calculates P:S to about 1:3.6 (caveat: this number is not very precise, since due to laziness/missing information, I treated the hydrogenated canola like the 100% hydrogenated soy like offered by many calculators. I have reasons to assume that my stuff is not fully hydrogenated, but at least partially elaidic). More extreme P:S ratios were not possible within limits of reasonable soap recipes, unless I had expanded my oil/butter/wax library even further. In fact, the above mentioned thread was (one of the) reasons why I had bought Japan wax in the first place.

I now have three soaps that are identical from their fatty acid profile – except for one that obtains its hardness virtually exclusively from palmitic acid, the second from stearic acid, and one in between with equal amounts of either. Tomorrow is picture time! A few days in, I'll start comparing their mechanical hardness, solubility/lathering, and skin feel.
 

ResolvableOwl

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p+1+s_T+13h.jpg


Unmolded after 13 h. The P soap (left) was nice and hard, and as shiny as the glossy silicone mould. It had developed a beautiful, dense and even camouflage of stearic palmitic spots. Preliminary result 1: These cannot be stearic spots (in the narrower sense). I have the Japan wax under suspicion to trigger those at any non-HP technique. I actually like the look and might consider using them as a stylistic element

The 1:1 mix soap was hard and glossy too, but also somewhat translucent; it didn't produce any spots. Preliminary result 2: palmitic and stearic acids might mutually block/suppress crystalline separation. Inconclusive though; with former cupuaçu/rice bran batters, I sometimes got stearic spots, sometimes not.

Finally, the S soap. It seems that I really have messed up with it 😭. Obviously, my CPOP-late mixing was not thorough enough to stir up all of the settled lye, yet so strong that it destroyed the finish, and it looks as rustic as HP soap now, plus that whitish stuff at the bottom. So far, no hints of stearic spots, but the upper (translucent) phase still feels greasy.
The soap cube is still soft enough to be pliable. Give me advice: Should I knead it thoroughly to incorporate the separated layers (with gloves of course), and/or give it another emergency CPOP? Only the S soap, or the other two as well? For the time being, I don't let them dry out like I would with regular curing.
 

aosproducts

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View attachment 55915

Unmolded after 13 h. The P soap (left) was nice and hard, and as shiny as the glossy silicone mould. It had developed a beautiful, dense and even camouflage of stearic palmitic spots. Preliminary result 1: These cannot be stearic spots (in the narrower sense). I have the Japan wax under suspicion to trigger those at any non-HP technique. I actually like the look and might consider using them as a stylistic element

The 1:1 mix soap was hard and glossy too, but also somewhat translucent; it didn't produce any spots. Preliminary result 2: palmitic and stearic acids might mutually block/suppress crystalline separation. Inconclusive though; with former cupuaçu/rice bran batters, I sometimes got stearic spots, sometimes not.

Finally, the S soap. It seems that I really have messed up with it 😭. Obviously, my CPOP-late mixing was not thorough enough to stir up all of the settled lye, yet so strong that it destroyed the finish, and it looks as rustic as HP soap now, plus that whitish stuff at the bottom. So far, no hints of stearic spots, but the upper (translucent) phase still feels greasy.
The soap cube is still soft enough to be pliable. Give me advice: Should I knead it thoroughly to incorporate the separated layers (with gloves of course), and/or give it another emergency CPOP? Only the S soap, or the other two as well? For the time being, I don't let them dry out like I would with regular curing.
 

aosproducts

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How to buy such high-quality soap that you are sharing here publically, it is looking very attractive
 

Tara_H

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Should I knead it thoroughly to incorporate the separated layers (with gloves of course), and/or give it another emergency CPOP?
I'm inclined to say both... Given my soap dough experiments, if you have been keeping it out of the air and it's sufficiently soft then grating/blending/kneading it, squishing it back into the mould and then CPOP seems like a reasonable approach.
 
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Kneading soap into soap dough changes the finished texture and lather of the soap, and also the crystalline structure it settles into, I believe. I didn't do my most thorough read of your experiment goals, sorry, so I'm not sure if that's relevant to you, but I'm mentioning it because it's not an even fix for unmixed soap if you're expecting the poured lather and texture. Trying to gel it again might help, but it might not, and you might not know if it undid kneading's alterations or not.
 

ResolvableOwl

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Thanks for the suggestions. @GemstonePony You're right, kneading would have impaired comparison between the three batches; I wouldn't have known any more if I compare recipes and/or technique.
I eventually opted for the most obvious variant: just making the S[2] soap from scratch again. It again was painfully slow until trace, now it's in the oven for the CPOP ritual. Fingers crossed, the only difference to its companions is then one day of curing time.

The “failed” S[1] btw, might just turn out fine, I'll give it some more time. It had already hardened up considerably at the time of my decision, the main reason for a new batter was that I wasn't sure if it would just crumble away. The greasy feel of the translucent layer went away, and the white stuff actually felt soft and pliable.

Learning the hard way why you should just leave a CPOP soap up to its own once in the oven…
 

ResolvableOwl

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Update. One of the soaps I cast from the second S batter had turned itself into soap dough unplanned (still too soft after 12 hours of CPOP rest). I got anxious and kept the actual S[2] sample in the mould for another day. Now it unmoulded just fine (upper right bar in the photos, the lower right is how the S[1] looks today).

Although the cupuaçu gave the S oil blend an appreciable yellow colour (much more intense than the rice bran oil), the soap actually turned out much whiter. It looks a bit “chalky” (not soda ash) and is still quite soft. A lot of very fine stearic spots (this time for real) developing throughout.

p+1+s_T+64h.jpg

Both the P and the 1:1 soaps have kept their mirror-smooth glossy surface, which buckled a but for the P soap at the sites of its palmitic spot leopard pattern. I hope for the soda ash ghosts to spare them!
Cautiously good news from S[1]: the whitish sediment at the bottom appears to be similar to S[2], It might be fine, just ruined texture due to my impatience.

I'll update in a few days, when all the young soaps have had a fair time to do whatever young soaps do while sitting at a dark and breezy place.
 

ResolvableOwl

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No update. I'm just stupid. My current practice to use up my cupuaçu and rice bran oil had distracted me from a much more obvious way to carry out this experiment: split a high-oleic recipe into two, and add that palmitic and stearic waxes into each. 30% different ingredients mean a lot less opportunity for differing behaviour than 91% different ingredients.

I have already drawn some conclusions from this trial. Should I ever get my hands on some actually 100% hydrogenated vegetable wax (full stearic, not elaidic), I might repeat it with two thirds less sources of error/uncertainty.
 

ResolvableOwl

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Update (207 days in)

p+s_T+207d.jpg

Like already suggested in my last non-update, I expect this to be more of a test of the peculiarities of “luxury” ingredients, rather than an artless and rational comparison of fatty acids.

Or not. Honestly, neither of the soaps really convinced me. Yes, they give off lovely, creamy lather, and yes, they leave a pleasant skin feel, but other soaps do so just as well. They have served their purpose, though. At least from the limited perspective they're allowing me, I can draw following conclusions:
  • Ease of lathering, creaminess and density are not very different. I find palmitic and stearic acids very similar if and only if they are CPed, sourced from natural oils/butters/“waxes” (not hydrogenated, not fractionated), and paired with “standard” amounts of lauric oils (PKO in my case). The reason why I'm so cautious here is that I have, over the last half year, found inconsistent behaviour in several cases, that necessitate above restrictions. Only this way I can draw at least some positive conclusion.
  • Speed of lather is slightly in favour of high-P. While my limited testing is not representative for longevity, I'd guess it's quite on par, with slight tendency to high-S.
  • That said, the hardness of neither of the soaps convinced me. After more than half a year of curing, they are still feeling soft, waxy, and slightly sticky, “as if they would need another week or two of curing”. Speaking of optical appearance: it's only the weird separation on the underside of the S[1] soap that makes it appear more white/opaque. The S[2] soap appears to not have gelled. Idk. Maybe an indication that high-S soaps need a higher CPOP oven temperature to reliably go through gel phase. Unfortunately, I cannot reconstruct all details of my CPOP protocol back then.
  • The stearic spot “snow” in the P soap has become weaker, but is still present. With the aggressive CPOP conditions in mind, actually stearic spots should be out of question, and texture & translucency wise it's definitely gelled. Is it a side effect of japan wax?
  • Cupuaçu butter. As elegantly as it behaves in soap batter (lowest false trace tendency of all hard oils I know), it doesn't bring the hardness into soap that I'd wish/expect from an oil that high in saturated FAs. Good news for those spendthrifts who dislike the smell of cocoa butter in soap: unrefined cupuaçu butter smells more or less the same as cocoa butter (Theobroma spp., just sayin'), but unlike cocoa, this smell entirely dissipates during saponification/cure.
  • With little differences between P and S, the balanced soap in between is just that: in between. It brings nothing unique.
What's next? I think I'll mince them into tiny cubes and give them a new home embedded into a lovely confetti soap.
 

true blue

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Good news for those spendthrifts who dislike the smell of cocoa butter in soap: unrefined cupuaçu butter smells more or less the same as cocoa butter (Theobroma spp., just sayin'), but unlike cocoa, this smell entirely dissipates during saponification/cure.

I realize this is a little off topic from your experiment, but ... you can get the smell of cocoa butter to come through in your soap?! How great that would be! Unfortunately, the smell totally disappears for me. I do OHP though, so maybe that makes a difference.
 

ResolvableOwl

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YMMV with CB supplier/quality, but in my CP experience it does hold. Just recently there were a few threads about it:
There are even warnings all across the internet to not overdo (unrefined) cocoa butter, since the chocolate smell is, while not strong, but certainly dominant at times, and doesn't fit to every situation.

I'd guess that HP would do just as well as CP, if not even better (since you might add cocoa butter at post-cook time). But who knows?
 

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