Let's Talk 'Fatty Acids'

[Shirley-D]

I don't know whether a 50:50 mix of palmitic and stearic acids is significantly different in soap ...

I'm as curious as a cat. This weekend I made a very small loaf of a mostly palmitic soap, another with equal palm and stearic, and then one of mostly stearic. (Surely somebody has already done this?) A pinch of different color mica was mixed into each loaf so I wouldn't get them mixed up. In a few weeks there should be some clue as to the differences. I am already sure there will be differences because they behaved differently when making them. We know stearic is less soluble than palm, but does it matter much? Is it worth sacrificing longevity for a really bubbly bar? What is a happy medium? What is the bell curve like? Is there a lot of latitude? I love bubbles but need more longevity.
P=palmitic, S= stearic
The pink soap on the left is P 25%, S 5% = 30%
The blue in the middle is P 15%, S 15% = 30%
The green on the right is P 6%, S 24% =30%
All the other fatty acids in the three soaps were almost identical. I can put the recipes in if anyone wants to see them. I know the pink and green soaps are extremes, but it is just for this test.

(Wish I hadn't bothered with the dried rose bud on the pink soap.) I don't use palm so I bought 8oz of palm oil at Hobby Lobby just for this experiment. Compared to my usual soap it was nice to deal with and traced slower than I am used to, which I appreciated. The equal parts soap was also nice but traced a bit faster. The mostly stearic was a pain to deal with. I narrowly avoided soap on a stick! It was stop and plop. No stick blending needed.
Fortunately, I knew that was coming and was ready for it thanks to previous wisdom from @ResolvableOwl. I had to use some free stearic acid to get the numbers up and that instantly saponifies. But I had to do that for the sake of the experiment. This morning it doesn't want to come out of the milk carton. I will try to release it tomorrow. By the way, the blue and the green soaps are vegan and palm free.

Another question: I didn't make a swirled soap, so am I not mixing well or is the mica sinking down? I think the swirls are pretty but not what I expected. I know there is ash on top.

 

[Shirley-D]

I couldn't help myself. (GROAN!) I sampled the end cuts from my fatty acid experiment. I know it is too early and it is far from cured. However, I have seen Mrs. Soap and Clay on YouTube testing the lather the very next day. So, I tested the lather too. I will, of course, reassess and report after they are cured, but this was too interesting to hold back.

To recap, Left is very high palmitic, middle is equal palmitic, and right is very high stearic. See above post for numbers.
The very high stearic was hard to handle, nearly soap on a stick. It was also difficult to unmold, and had a lumpy feel and giant stearic blobs. The other two were manageable.

First, the high palmitic lathered very nicely and quickly with good bubbles. But it was weak and had no body. It quickly lost the bubbles and didn't become creamy. I would describe the lather as watery.

The equal parts P and S was delightful!!! It produced really nice bubbles which stayed around and then became creamy/foamy. Lovely!

The high stearic also bubbled nicely and quickly. The bubbles also became foamy/creamy and eventually kind of stiff but still acceptable.

I placed a big wad of the lather from each soap on the side of my kitchen sink. After 10 minutes the high P lather dissipated into a watery puddle: the equal P and S was a light fluffy puff ball; the high S stood up strong and stiff. I poked it and it poked me back! Not really but it was that stiff. LOL!

Blobs of lather at minute 1

Same blobs after 10 minutes

Top is high palm, middle equal parts, bottom high stearic.

If the palm to stearic ratios were a continuum, I would try to place my soap a bit right of center. I like bubble but need some longevity for my softened water. I will follow up in a few weeks with the final report.
Happy soaping!

 

[AliOop]

Great testing notes - thanks for sharing those! It's also a great visual as to why shave soaps are always high in stearic to get that long-lasting lather.

 

[Ladka]

Very interesting! Thank you for your detailed explanation.

 

[earlene]

Wow, what great detail on the lather! Guess I'll avoid the very high Palmitic recipes. Thank you for doing that work, @Shirley-D, and for your excellent notes & photos.

 

[DeeAnna]

Nicely done! I'm curious to follow the rest of your journey.

 

[Shirley-D]

Nicely done! I'm curious to follow the rest of your journey.

The verdict is in! These soaps in my hot dry climate are well and truly cured to a crisp at 7 weeks. To get straight to the point, they are all lovely soaps and I will enjoy using each one. Yes, there is a difference between hight palmitic, equal amounts palmitic/stearic, and high stearic--but it is so slight I am not sure it is my imagination. All three soaps bubbled up nicely and made a delightful thick lather. What a difference a good cure makes (you all knew that).

The very high palmitic soap suds.

The equal palm and stearic suds

Mostly stearic suds

They are all very lovely soaps, but if you forced me to pick one I would say the equal palm/stearic might have been a little fluffier than the others. Maybe not. If they were not color coded I don't think I could tell them apart.
As for the BOTSOTS test (Blob On The Side Of The Sink), they all held up very well. At 10 minutes they were still there, at 20 minutes there was very little difference. After that I was tired of looking at them and washed them away. Who needs a blob of soap foam for longer than 20 minutes.

BOTSOTS at 10 minutes

BOTSOTS at 20 minutes, any difference is due to my handling.

So the take away from this for me personally is, I don't need to worry about getting the palmitic higher in my palm-free soap. I only need to get the combined total to 30 or above. That's a relief.
As soon as I find the time I will report on my cactus juice soaps.
Happy soaping!

 

[Zany_in_CO]

As for the BOTSOTS test (Blob On The Side Of The Sink), they all held up very well. At 10 minutes they were still there, at 20 minutes there was very little difference. After that I was tired of looking at them and washed them away. Who needs a blob of soap foam for longer than 20 minutes.

 

[DeeAnna]

I really appreciate this info, @Shirley-D -- thanks for sharing!!!!

I have a very good idea about the amount of work and thought you put into this -- kudos to you for doing this experiment.

 

[Ephemerella]

@Shirley-D Really admire all this hard work and your generosity in sharing! This newbie is eagerly following your journey, thank you!

 

[Shirley-D]

Thanks everyone
You know everything I learned came from this forum.

 

[VikingChick]

BOTSOTS - I feel like that should be a new standard by which we judge soap. Nice job performing and documenting your experiment!

 

[KiwiMoose]

Love your work @Shirley-D

 

[Shirley-D]

Love your work @Shirley-D

Thanks @KiwiMoose, you have been a help to me with the soy wax info

 

[dragonmaker]

Excellent experiment idea and method! I just found this thread, and I'm so glad you shared!

 

[NcDon]

Hello,
Are these numbers good enough for my CP soap recipe? In theory, everything seems fine. Gray areas show ranges of good values.

 

[KiwiMoose]

Hello,
Are these numbers good enough for my CP soap recipe? In theory, everything seems fine. Gray areas show ranges of good values.

View attachment 72354View attachment 72355View attachment 72356

You are using a high percentage of OO as I understand it, and this means that you can throw the FA profile out the window. OO makes a good soap but it doesn't look good in the soap calculators.

 

[dibbles]

Is your lye concentration set to 99%?

 

[NcDon]

Is your lye concentration set to 99%?

View attachment 72359

Yes, I use solid caustic soda micropearls produced in France type PDS-NaOH-100-TA-0001 with total alkalinity >= 990 g/kg, usually 99.7% or so.

 

[dibbles]

@NcDon, I don't know which soap calculator you are using, so I might be misunderstanding this one. In all of the calcs I am used to, Lye Concentration refers to the amount of NaOH in the liquid used to dissolve it, not the purity of the NaOH itself. So, a 50% lye concentration would be 50% NaOH and 50% water or other liquid. NaOH needs at minimum an equal amount of liquid (by weight) to dissolve properly.