Dual Alkali Soaps (NaOH & KOH)

Hello everyone.

After reading some posts over the forum:

Castile 95%NaOH 5%KOH calculations help

Cold Processed - Combination of NaOh and KOH

I had also made a small experimental batch.

The two recipes where:

Olive pomace: (95%)
Coconut: (5%)
with EDTA 0.5% and paprika infused in Olive Oil

But their main difference was that the one was made with 100% NaOH (along with a few drops of yellow pigment) and the other one was made with 95% NaOH and 5% KOH (with no extra color).



I used them a few days ago after 4 months of curing (didn't have the time to test them earlier) and I can see what DeeAnna has already experienced by a dual alkali CP soap.

Although I had used 5% CO in order for me to use the one alkali (NaOH) soap (because I hate Castille), their difference is visible.

The NaOH soap doesn't form bubbles in my hands right away but it leaves this weird jelly - soap - film thing that when I introduce a little more water and friction (after I park the soap on the soap dish) then the bubbles arise. With the dual alkali soap, some bubbles start to form in my hands before I park the soap on the soap dish, and it behaves as if a little more Coconut Oil was present in the recipe.

So KOH is making the soap easier to dilute, as the same happens with the shortest fatty acids (myristic, lauric), and that is an enabler for me to make another soap that will have 80% OO and 20% Palm/Lard made with 90% NaOH & 10% KOH. I guess the result will be promising...

A great comparison of the two - thanks for that. I think next time I'm making a high OO soap I'll use 5% koh

I was curious if this dual lye thing had any effect on regular recipes. Turns out it makes much larger bubbles and "frothier" lather in a high lard soap. I really am amazed. I have two batches out to testers right now to verify if it is just my imagination or not.

I think the difference of adding KOH is most obvious with a high oleic soap (high in olive, high oleic sunflower, HO safflower, avocado, etc), as Nikos explains.

But I agree with Susie -- I also see a change in the lather from a high stearic-palmitic soap too (high in lard, tallow, palm, butters). The added KOH => fluffier bubbles and quicker to lather. The soap behaves as if it has more coconut oil than it actually does. That said, I also wonder if the placebo effect is influencing me, so I'm curious to hear what your testers say, Susie.

I doubt the KOH will do much to a soap high in lauric-myristic acid (coconut, palm kernel, babassu), because that type of soap is already pretty soluble in water.

I used my usual recipe of 65% Lard, 15% CO, 15% OO, 5% Castor Oil, and 5% superfat so that we would have a test with the ONLY difference being the 5% KOH. We'll see.

I warned my testers that I would be having them stop using a bar in the middle to try a new one, so I should hear today or tomorrow.

ETA: I had the hubby do the test with me timing. The dual lye soap made bubbles 6 seconds faster and they were much larger bubbles.

Well it is known that KOH makes more soluble salts of fatty acids meaning that the soap needs less water and friction in order to start its solubility. And by introducing KOH in a CP NaOH soap we actually adjust the soap bar's solubility (maybe just like sugars and castor oil do).

Kevin Dunn has somehow categorized the three bases in the order of solubility from difficult to easier:

1) Sodium salts of fatty acids are water soluble created by the strongest base NaOH
2) Potassium salts of fatty acids are even more water soluble and are created by the also strong base KOH
3) Ammonium salts of fatty acids are extremely water soluble and are created by the weak base NH3 - Ammonia (gas)

(I think that this is what he has described in general at Chapter 8 & 10 of his book, correct me if I'm wrong).

I have never made Castile soap but am thinking of doing a batch with 5% KOH. I'm very interested in following this thread and also hearing about people's experiences using 5% KOH with a typical 3- or 4-oil soap recipe. From other sources I have read, using 5% KOH with 100% OO can shorten the cure time from a year down to 8 or 9 months. Is that true? Thanks for all the information!

Scooter

Susie said:

I used my usual recipe of 65% Lard, 15% CO, 15% OO, 5% Castor Oil, and 5% superfat so that we would have a test with the ONLY difference being the 5% KOH. We'll see.

I warned my testers that I would be having them stop using a bar in the middle to try a new one, so I should hear today or tomorrow.

ETA: I had the hubby do the test with me timing. The dual lye soap made bubbles 6 seconds faster and they were much larger bubbles.

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Hi Susie,
Did your testers get back to you with their opinions on the KOH soap?

Do you use KOH in all of your soaps now?

I use KOH @ 5% in all my soaps, yes. But I am a bubbleholic. Everyone agrees with me about the bubbles.

This is amazing. I've recently gotten into making liquid soap, so I have tons of KOH on hand (dual lye liquid soap maker here!). I'm super excited to try dual lye bar soaps!!!!

I make all my soaps, other than salt bars, with dual lye and really like them. Since I go low with the CO I can use all the help I can get with bubbles.

I'm another convert. It's really easy to do if you have the KOH and I like the results a lot. I weight my 50% NaOH masterbatch in one pitcher, measure out the extra water (or beer, milk, etc.) in another, and put the dry KOH into that second pitcher. It dissolves fast in that much liquid.

So lucky to have found this article.. I was planning to make another batch of castile soap. But this time with rice bran oil.
Wil try using this method..

Anyone has any experience with 100 rice bran oil? What shld i expect n need to know before i make this.

It's high in linoleic acid, so it may be more prone to rancidity. For that reason, I personally wouldn't make a mock castile with all RBO. But YMMV -- there's absolutely nothing wrong with trying it.

DeeAnna said:

I'm another convert. It's really easy to do if you have the KOH and I like the results a lot. I weight my 50% NaOH masterbatch in one pitcher, measure out the extra water (or beer, milk, etc.) in another, and put the dry KOH into that second pitcher. It dissolves fast in that much liquid.

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I masterbatch my KOH separately. I do this because the amounts of KOH in each recipe are so small that doing a 50% masterbatch means I can weigh out twice the amount a bit more accurately. I now have a scale that’s a bit more accurate but keep doing it because it’s easier for me anyway.

Yeah, I can see that, PenelopeJane. Good thought!

Also if the KOH is at all dusty or static-y, using masterbatched KOH solution nearly eliminates the problem of dealing with the dust and static.

I also masterbatch my KOH

I keep my working KOH in masterbatch form.

isha said:

So lucky to have found this article.. I was planning to make another batch of castile soap. But this time with rice bran oil.
Wil try using this method..

Anyone has any experience with 100 rice bran oil? What shld i expect n need to know before i make this.

Click to expand...

Yes, in July of 2017 I made two batches of 100%RBO soap. One with NaOH and water as my lye solution, using a 40% lye concentration and zero SF. It gelled via CPOP, but I had to CPOP at a slightly higher temp the second time as with the oven below 100F and the high lye concentration, it only partially gelled. So I put it back in the oven at a higher temp to get it to complete the gel.

The second batch was with vinegar & NaOH (and water) as my lye solution, using 31.3% lye concentration and zero SF. This one gelled completely the first time with CPOP, but I started out with the oven at a higher temp (154F then turned off when I put the soap inside the oven) due to my previous soap, just to be sure.

Both soaps also have EDTA & ROE (ROE in the oil when opened) to ward off DOS and help with soap scum (the EDTA does dual duty). Both are fragrance-free. One is uncolored and one is colored with yellow, so I can differentiate between the two.

Both soaps are now 7 months old and IMO not yet at their possible prime. I did not bring any with me on this trip, so can't give you an up-to-date report on how they are performing, but so far (as of about 3 weeks ago) they have not shown any sign whatsoever of becoming DOSy. I currently don't recall how they compare to Castile, but IMO it's too soon to tell if I like or dislike this as a single oil soap. I don't have any notes on performance at hand (I am not at home.)

I have not yet tried 100% RBO as a dual lye soap. I wish I had done so when I did these two batches, buy I was going for a comparison between added SA (thus the vinegar) and plain.

What you can expect is that with a higher lye concentration, it traces fairly quickly. My [40% Lye] went from emulsion at 2-2 1/2 minutes to light trace at about 3 minutes and then medium trace at about 5 minutes after just sitting when I stopped stirring at 3 minutes. I did not make a notation about how long it took the same soap with a lower lye concentration to come to trace, but if it had been remarkable, I would have made a note of it.

Both soaps are quite hard, but not being near them I can't give a more objective report on hardness than that. 'Quite hard' is really a subjective term when not backed up by something tangible/measurable.

I made both last April. One batch with Pomace OO and one with RBO. Both had a high lye concentration and a low SF just to keep things on an even plain.
No DOS on either. The OO did "green up" a little so I can tell them apart by just looking at them. Since they were both single lye soaps they are both snotty and seem to clean the same.

Since I am not a big fan of the castile snot I prolly won't repeat that experiment.