Tracing/saponification speed test

[ResolvableOwl]

Some time ago, for a bar soap, I combined (what I thought) soft/slow oils and lye, just to see how it would go to thick trace within the first second of stick-blending. Hrm. Time to find out if some of my oils misbehave (by chance, they were all newly purchased/opened).

So I went on, grabbed some PP test tubes with lid, weighted 10 g of each oil, and added the appropriate amount of 25% KOH solution (9–12 g, zero superfat). Repeated short, vigorous shaking with rest times in between, until emulsification/trace/saponification takes off. I'm wondering if this wouldn't be a good way to quantify these fishy “fast/slow-tracing” properties of oils in a more reliable, quantitative way than just gut feel?

The candidates under observation: Sesame, HO sunflower, castor oil. I extended the test to some other oils that I happened to have around, so I did the same with babaçu, mango butter, and unrefined fLaxseed oil (with two drops of ROE).



I weighed the oils into the test tubes, tempered all to 40°C in a water bath (to melt up the solid oils), and carefully dripped in the lye, without mixing at first.
After the first shake, not much happened, except that the lye and oils became turbid (most with S, L and B). 10 minutes later, second shaking. Some trends begin to stand out. The “quicker” oils (those to come to unstable emulsion first) were surprisingly S and L; B and C were a bit more hesitant. M and O behaved indifferently.

A few shake-stand cycles later, things approached their more expected order, i. e. the B and M thickened up considerably, while the liquid oils were hard to convince to stay in stable emulsion. C made it a few hours later, the edible oils needed to stand overnight.

The other day, all batches have more or less saponified into a gelatinous goo. I diluted each with 250%TOM water. O, S became a snotty oleic slime. C and M hardened up to a point where I had to stir in the extra water. B was solid at first too, but easily dissolved in the extra liquid. L has turned syrupy. After a bit more of shaking/standing/heat bath, M absorbed the extra water to become a paste like solid honey. C dissolved completely into a clear, runny solution. B stayed liquid too, but some turbidity remained (for now).



In any case, it is

1. fun to play with, and interesting to see the viscosity of at (roughly) identical concentrations of single-oil CP liquid soaps
2. rather obvious to me that the sesame oil was the one that bugged me in my earlier bar soap. Initially it was even more eager to cloud up than B/C/M, and it added the most turbidity to the lye after the first shaking. In the end, though, it turned out to be the lazy, slow-tracing oil that I'd expect from its mostly oleic/linoleic composition. Anyhow, next time I'll use S, O, and/or C in soap, I'll whisk it with a spatula first, to see if I might spare cleaning the SB afterwards, lol. I'm glad it most probably wasn't the castor oil at least.
3. More or less inadvertently, this is also the long sought-after “-ate” assembly kit that @Johnez had wondered some time ago – though for LS, where it is of course a lot easier to combine individual sesamates/mangobutterates/babassates… than it is in bar soap. Some ideas to test: Necessity/performance of castor oil to boost lather; skin irritant effect of lauric oils (babaçu) in between 0…100%; reaction of oleic/linoleic/ricinoleic/lauric/stearic oils to thinning with water and thickening with sodium salts; castile dryness vs. soap blend…

Stay tuned!

 

[Becky1024]

I love science experiments! It will be interesting to see developments!

 

[ResolvableOwl]

Upd“-ate” (pun intended)

The oleic/linoleic soaps S and O are remarkably stiff (wobbly like fried egg/agar gel). Remarkably, M is softer and has the consistency of semi-solid honey. L looks and flows like liquid (slightly turbid) honey. C stayed water-clear.

The one that bugged me was B; some lipid sediment had settled at the top, though I'm for one sure that the babaçu yields clear LS, and that I'm at zero/slightly negative superfat. I've added some extra lye (+15% KOH to be on the safe side) and now I'll await whatever will happen.

Further plans: 1. dilution series with watching at which concentration the respective mono-soaps show which characteristic viscosity; 2. foamer test: how well each soap is performing in a foamer bottle.

 

[ResolvableOwl]

Tiny update

I've given up with the Babaçu (left). I added another 15% (oil equivalent) KOH and gave it three days to react, with occasional shaking. Still there is this rim of lipids floating on top. I've lightly shaken it just before the photo so you see it's milky at the top, but nearly transparent at the bottom. I really don't know what is going on there. My lye isn't kaput – that sud lye-heavy and zappy as hell! I'm curious if the turbidity disappears upon dilution.

Next, we have a seventh trial soap! In the middle is cottonseed oil (lat.: Gossypium), treated just like all the other oils. As a high oleic/linoleic liquid oil, it falls in line with sesame and HO sunflower, it is opaque and has an agar-like gelly structure. I'm curious if it'll share some similarity with the mango butter later on when diluting, due to the above-average content of saturated fatty acids in cottonseed oil.

Right: the castor oil soap: water-clear, just like I would have expected the babaçu to become too.

 

[ResolvableOwl]

Oof. A lot of text, and many many data points ahead!
It's so difficult to find decent LS dilution numbers, so I made them myself. The table below is meant to assist roughly locating the concentration range close to desired properties. I made it for myself in the first place, but feel free to use/extend it if you find it useful.

I restricted to single-oil LSs; YMMV for oil blends (and glycerol additions etc.). More specifically, I'll think up (or get recommended/requested by you ) specific blends at some concentrations, to use up the remaining soap pastes in a productive manner (my workhorse LS at the sink is about to run out soon).

I first tested foamer performance whenever a soap became runny enough to be easy to work with a foamer (and heck, I now know very well how to clean foamer heads!) – dependent on the oil in question; and then once again at a low concentration. I was surprised how little difference it made. Bottom line: foamers are incredibly economical, and you really should try out how far you can go with dilution (5% are for sure not the limit for LS+foamer, it was my limit due to exhaustion/laziness).

To little suprise, the recipe recommendations falling off this trial aren't too different from existing LS recipes. But this effort helped me to understand better why the recipes look that way:

• Oleic acid as workhorse soap: gives the thickest viscosity at low concentrations by itself
• Lauric oils: lather carriers, action is virtually independent of concentration
• Castor: supports lather formation
• Long-chain saturated FAs for creamy lather and (in a limited concentration range) pearlescent appearance of the LS itself
• Linole(n)ic/PUFAs??? Read on, it's worth it!

For sure these insights have clarified my understanding of LS and will enter my future LS recipes and preparation protocol.





How to read the table below:
The rows are the soap concentration. Since there is no commonly accepted and practical way how to designate LS strength, I opted for oil % of total mass: grams of oil needed for 100 g of the diluted soap. That makes comparison between oils with different SAP values easier. The concentration decreases as a dilution series; each row has 3/4 of the concentration of the former.
For each oil and concentration, I eyeballed the viscosity (first symbol) and opacity (second symbol) after dilution and waiting for the mix to equilibrate (took hours for stiff paste, and a mere whisk for runny liquids). Of course both parameters decrease during dilution, but this process is faster or slower depending on oil.

For long-chain oils, the optimal “honey” LS texture is in the range of 10–20%, and a high content of oleic acid tends to shift this window to lower percentages, while both linolenic and palmitic/stearic acid lift it (I now regret that I don't have included a truly HL oil like safflower, sunflower or poppy seed oil, so I can only extrapolate from the M-S-G line).
Lauric oils (coconut) and castor are viscous only at ridiculously high concentrations (> 30%); below this they don't contribute to thickness.

In the “ideal” (honey-like) viscosity range for normal LS dispensers, most of my samples tended to still be a bit turbid. Though I had inteded to avoid excessive superfat, there are suggestions that I've been just above the threshold to easily reach clarity (KOH purity? scale precision?). Clarity also is a matter of subjective perception, HP vs. CP (mine were CP), additives, unsaponifiables, and personal preference. Take my values with a grain of salt.

Due to low solubility in water, long-chain saturated FAs don't contribute to the properties of the LS itself. That's why, e. g. mango butter LS is less viscous than sunflower LS at the same concentration. But it's still soap, so the soap-performance-per-thickness ratio is better with “hard oils” – but mind that the palmitic/stearic soaps tend to sediment to the bottom if the solution is too thin (most noticeable at the 5% mango soap).

Foaming is by and large in line with bar soap folklore, but has some surprises to offer. Lauric oils are lather kings at any concentration. Oleic acid mostly disappoints at this subjective, cosmetic parameter. High content of long-chain saturated FAs (M, G) makes lather dense, creamy, and long-lasting.
What really did surprise me was that with increasing unsaturation, lather became more dense and lasting. Up to flaxseed/linolenic acid, that gave the most lather of all long-chain oils!

Once again its own kind, castor oil has another surprise to offer: through a foamer bottle, it bubbles very readily to give a medium-sized foam of a somewhat “glassy” appearance, that decays quickly and is loud at doing so. The tiny bubbles burst like soda, sherbet or bath bombs.
Maybe that's part of the lather boost secret of castor oil: combined with “boring” (e. g. oleic) soaps that can support foam, but don't lather up by themselves, the passionate but short-lived nature of ricinoleic lather is able to “live out” and to mutually support the strengths of the ingredients, while masking their weaknesses.


What I have not done so far is to give sodium-based thickening a try. I certainly won't do it as extensively as the other data here, but will give it a try for selected oils/concentrations at least (Requests?).

% oils in soap	HO sunflower	Sesame oil	Mango butter	Cottonseed oil	Flaxseed oil	Coconut oil	Castor oil
40 %
30 %						[]
23 %	🕯	🕯	🌨	🕯	🕯		[]
17 %	🕯	🕯	🌨	🕯	🌨
13 %	🕯	🕯	[]	🕯 []	🌨 []
9 %	🌨 []	🌨 []		🌨
7 %			🌨	🌨
5 %	[]	[]	🌨 []	[]	[]	[]	[]

First symbol: texture/viscosity

	stiff, jelly-like, does not stick to walls
	pasty, creamy
	honey/syrup viscous
	thick liquid (~ castor oil)
	runny, watery

Second symbol: clarity

🕯	fully opaque
🌨	cloudy, turbid
	shimmering/pearlescent
	clear

Third symbol: lather performance with foamer bottle [only at selected concentrations]

	loose, translucent, unstable foam
	medium dense and fine foam
	fine and creamy foam
	very fine, white, rigid foam
	foam long lasting/slowly degrading
	foam breaking down loud and quick

I had decided to ditch the babaçu soap, since its turbidity issues didn't disappear. Instead, I did well in making another sample soap from refined coconut oil, that was much more well-behaved, and apart from some stubborn foaming at very high concentration, instantly gave a clear LS without adjustments.

 

[Becky1024]

Wow! Lots of great data and observations. What surprised me the most was castor oil in a foamer. I would think that the bubbles would hold much longer due to the ricinoleic acid. But it would be interesting to hear them pop!

 

[ResolvableOwl]

That castor is really an oddball. Pure castor bar soaps are said to have anywhere between average lather/poor stability and zero lather at all – with my recent observations, my guess really is that ricinoleic acid is much “faster” than regular FAs to create bubbles, but also to destroy them, unless soap from another oil “carries over” these bubbles.
I wonder how far this narrative holds. Maybe it can explain some weird outcome of soaps with high (higher-than-usual) castor content.

ETA: It's never been easier for me to test this out. I'll somehow mix together the single-oil LSs anyway, that's just a matter of the order in which I do this.

ETA2: I'll see if I can make an audio record of the castor froth decaying. A perfect useless thing to do on a bored evening.

 

[ResolvableOwl]

Now I had a few days to get warm with these thoroughbred newcomers. A few annotations:

• I'm absolutely in love with the sesame LS and its smell! It was organic, cold-pressed sesame oil (not roasted), and much of its nutty odour made it over into the LS. Particularly in the foamer, that does a great job to distribute the natural smell of the oilseed.
• Not directly clear in above table: [] is still very different from []. Lauric oils are just unbeatable when it comes to richness and density of foam (or, which is somewhat related, foamer bottle heads are just best optimised to whip up lauric soaps). From my observations, LS only from long-chain oils just cannot keep pace with coconut & friends. On the other hand, coconut is not the master of lather longevity, so the eternal truth ( is probably somewhere in between.
• As promised, here comes the multimedia-ised castor foam decay video. I tried hard to not hit my microphone with the foam, lol. And I'm also taking the chance to squeeze in advertisement for the amazing flaxseed LS. By the way, I combined the remaining slightly diluted L and C soaps, and I'd rate the resulting foam as [] as well: it was finer and stiffer than with L alone, and much more lasting than with the pure C, nearly as decadent as with coconut. Guess someone has got another favourite LS base recipe today

 

[MellonFriend]

I just gotta say I love your chart with all those different emojis. I love that you used an egg to denote thick liquids.

 

[ResolvableOwl]

It is really bizarre: one might well have the impression that there is an emoji for anything – but just until you need a very specific one, and you see how incomplete the set really is. Also it was very disturbing to see that the SMF post editor has different depictions for emojis than the forum pages themselves.

 

[Janewoc17]

Dear Resolvable Owl,
May I sit at your feet and learn from you, please?

 

[ResolvableOwl]

Yes, with pleasure!

First, open Emojipedia — Home of Emoji Meanings . Then, enter the search term “bubbles” and despair that there are countless variations of speech bubbles, bubble tea, etc., but the single promising soap bubble emoji is in draft only, and expected to be in widespread adoption not until next year. That's why I had to switch to the “ lotion bubble” emoji instead .

But I guess you meant something different . Much of my insights are already here above, but I'm planning to add a few new ones along using up the soap samples. I'm not quite there what I'd call a “recommendation” state, it's mostly raw data up to now, but I guess this will grow over time. for sure I'll challenge my findings with on-spot LS creation from scratch, and keep everyone updated.

 

[Becky1024]

Now I had a few days to get warm with these thoroughbred newcomers. A few annotations:

• I'm absolutely in love with the sesame LS and its smell! It was organic, cold-pressed sesame oil (not roasted), and much of its nutty odour made it over into the LS. Particularly in the foamer, that does a great job to distribute the natural smell of the oilseed.
• Not directly clear in above table: [] is still very different from []. Lauric oils are just unbeatable when it comes to richness and density of foam (or, which is somewhat related, foamer bottle heads are just best optimised to whip up lauric soaps). From my observations, LS only from long-chain oils just cannot keep pace with coconut & friends. On the other hand, coconut is not the master of lather longevity, so the eternal truth ( is probably somewhere in between.
• As promised, here comes the multimedia-ised castor foam decay video. I tried hard to not hit my microphone with the foam, lol. And I'm also taking the chance to squeeze in advertisement for the amazing flaxseed LS. By the way, I combined the remaining slightly diluted L and C soaps, and I'd rate the resulting foam as [] as well: it was finer and stiffer than with L alone, and much more lasting than with the pure C, nearly as decadent as with coconut. Guess someone has got another favourite LS base recipe today

View attachment 60131

The castor oil soap sounds like bacon sizzling in the pan!

 

[The_Phoenix]

@ResolvableOwl Sesame oil in soap is remarkable. I welcome the noticeable smell of the oil in the soap.

I can’t say much about the castor as I’ve stopped using it on my soap and don’t notice a difference. I do use it if want to create a recipe that moves quickly.

 

[Mobjack Bay]

Thanks so much for sharing your results. Did you mix the L + C soaps because they were what you had leftover, or was there another reason to use the L in particular?

 

[ResolvableOwl]

mix the L + C soaps

Two real reasons, and one retrospective pseudo-reason:

• Is a regular soap able to tame the rapid decay of castor foam? (no particular reason for L; maybe O or M would have been better due to their weaker foaming by themselves – i. e. I didn't really challenge the “lather booster” ability of castor in the most spectacular way)
• Is the L foam performance a lucky coincidence, or does it survive recipe modification? I really wasn't very optimistic about the L soap, since it had literally zero bubbles as a “gel” (with honey consistence at concentrations where other soaps really were stiff gels), nor when diluted to foamer fluid. So far, it looks like flaxseed oil is about an optimal “secret ingredient” to foamer LS: not the lamest to work with in CP, easiest to dilute, few bubbles when you don't need them, but abundant lather when in the foamer, and at least some robustness towards blending with other oils/soaps. Not to mention its faint, classy, caviar-like smell.
• I had mixed all the remains and dilution residues of the other soaps, and the resultant soap was, well, as if it somehow has sensed that it's just leftovers.

Another tiny update

Left the K (coconut). I just now realised that I hadn't properly introduced it here yet! It is, in principle, the same as the long-chain oils, just that, I have started two dilution steps earlier, i. e. at 40% oils, that's 115 g water and 26 g KOH per 100 g CO) – my lauric experience with the weird Babaçu had suggested that I can do so.

It has taken several days until all the foam from the shaking had settled. Just to find out that by now, there is some layer of “slush” floating atop. It's soft, but solid. This semi-transparent something is less dense than the syrupy liquid underneath. I've seen this before in another LS, and attributed it to incomplete soap paste dissolution – but it never really disappeared, even upon some further dilution. Also strange, this solution here has been smooth before (not water-clear, but clear enough, with the concentration of this soap in mind: the solution contains nearly as much oil by weight as water).
It seems that something is precipitating out. Not a separation like overdone salt curve, but something else is going on that isn't observable in long-chain oils, where achieving that high a concentration isn't possible in the first place.
Without NMR, X-ray diffraction or gas chromatography at hand, though, it's difficult to tell what is happening here.

Next, on the right is the latest addition to my growing LS family: High-linoleic sunflower oil. My goal with this is twofold. For one, previous oils were mid-linoleic at best (G and S), and I'm very curious if it is closer to oleic or linolenic acid when it comes to viscosity at some concentration, foaming, and (later on) thickening with sodium salt.
Then, I want to challenge “on-point” saponification in CP LS making: occasionally shake the test tube until I notice emulsion becomes stable/viscosity rises, then add the dilution water as the mix hasn't fully solidified/gelled yet. Skipping/easing that annoying LS paste dilution step would be a big thing, but the high initial lye concentration is needed to kickstart the saponification…

 

[MrsZ]

Your experiments and observations are fascinating! Thank you for sharing with all of us.

 

[ResolvableOwl]

still no news on salt curves…

…BUT:
Update: HL sunflower addition to the above table
Glad that I gave it a day or two longer than my original impatience had been up to – turns out that no-stir CPLS isn't quite done after 3 days, but there are still things happening – between day 3 and 5, the viscosity went up from a meagre to a respectable in the 23% stock solution. Upon dilution, something weird happened in the beginning: the soap turned from a cream into a gel (very wobbly, not very stiff), that turns into a viscous, sticky, ropy liquid upon stirring (shear thinning?). About as thick as the initial 23%, I still decided to assign the thickness attribute in the “wrong direction” to honour this extraordinary property.

% oils in soap	HL sunflower oil
23 %	🕯
17 %	🕯
13 %	🕯
9 %	🕯 []
7 %	🕯
5 %	🌨 []

However, take these observations with a grain of salt. Though zappy, I am under the impression that there is still (after nearly one week) some unsaponified oil in there (cloudy appearance, murky lipids settling at the top). Excess superfat might do this sunflower oil some injustice, most of all its foaming. Yet I don't know if it's worth waiting even longer. (If, in a few weeks or so, I'll use up this sample soap and should I notice a difference, I'll give an update here, of course!)



Consequences of new data on FA profile vs. soap performance evaluation:

H: largely falls in line the other liquid oils. Nothing particularly particular about it. Very unspectacular as-is, but might profit a lot from a lauric and/or castor bubble boost. It's mostly linoleic acid (18:2) – and this narrows down the contributions of other FAs (in the more diverse oils)…
G: Think of cottonseed oil as roughly H with 15% of 18:2 replaced by palmitic acid. It formed a considerably stiffer gel at start concentration: palmitate is a stronger geller than linoleate, but weaker than oleate.
S: From 18:1/18:2 ratio, it is in between H and O, and I indeed observe this. More dense foam on S possibly due to a tad more saturated FAs.
L: 18:3 appears to not contribute significantly to viscosity. But it does contribute to lather.


All these interpretations are based on the assumption that viscosity thingies are linear in concentration (highly doubtful), and FAs don't interact with each other (equally doubtful), and reducing the FA profiles of O to pure 18:1, H to 18:2, and L to 18:3 (somewhat justified). YMMV™



Based on this, this is my current state of recommendation for LS recipes in absolute numbers (to be challenged in future recipes):

Viscosity: To achieve thick LS (without salt trickery etc.), try to get the overall content of oleic acid 18:1 to 6–8% of final LS weight (lower values, down to half of this, if you have a lot of linoleic acid). Saturated fats are cosmetic only (opaque/shimmering optics, hardly relevant for viscosity).

Bubbling: 5% of castor/lauric oil are plenty. Long-chain saturated FAs help for a prolonged and denser/creamier foam. Of the unsaturated oils, only linolenic acid (18:3) has its own lather character. The others still act as soaps (and increase viscosity), but are unimpressive foam-wise.

Feel free to compare your own favourite LS recipe to these numbers.

 

[Johnez]

Never ceases to amaze me how much gold lies hidden in these forums, especially when stumbling across a thread by @ResolvableOwl . Its intriguing to see castor oil's performance, particularly with linolenic FA (flaxseed oil). I have some experimenting coming up myself (nowhere near this thread's caliber!) and hope to see castor oil wrest away coconut oil's grip on lather. Very inspiring thread RO, I'm in awe of how thorough and yet how readable your work is.

 

[ResolvableOwl]

Update: Mac(A)damia oil and (U)cuuba butter



Two of the oddballs that gave me woes lately!

Macadamia oil turns into this weird dirty pink, once in contact with lye. Instant emulsion upon the first shake. BUT it stays there, not much is happening afterwards. The emulsion only has limited stability; it won't fully separate, but some pinkish lye collects at the bottom. The oil phase looks like it curdled (sour milk…), and separate but not into droplets like any other oil, but into a pinkish-brown something with a texture that loosely reminds me of paper pulp prior to pressing.

The Ucuuba butter, for first, melts quite high (some 55°C) and has a strong false-trace tendency (unlike, e. g., mango butter), so “cold process” isn't easily possible and I didn't even try. Instead I put it into a jar with hot water to melt the brownish fat and kick-start the saponification … just to find out that after a few minutes, it has already completely solidified into a chocolate-like blob.
I've now already diluted it to 30% (or at least tried so), and will judge tomorrow if this was appropriate. Proper lauric oils (coconut, babaçu) were atviscosity at this concentration, but I'm aware the ucuuba has longer FAs with lower solubility … we'll see. Right now it looks like cappuccino, lol.