Dual Alkali Soaps (NaOH & KOH)

[Nanditasr]

... It still cleans and leaves the skin nice afterward, but I personally find the lack of bubbles to be very frustrating.
Increasing the solubility with a bit of KOH might make 100% lard soap a lot more pleasant to use. I'd given up on 100% lard, but I think I'm going to try that now.

Thanks; that's interesting to know. I don't have tallow or lard here, but I use palmolein.
Yes, I rather like the waxy feel of a palm bar. I also find that it lathers much better after about three months of curing. But yes, a little more lather (without having to use CO) would be nice. In my case, I'm going to try ammonia instead of KOH.

 

[DeeAnna]

"...why would one want to make a high stearic/palmitic soap more soluble -- isn't a harder, less soluble soap more long-lasting and therefore more desirable?..."

Sure less solubility and physical hardness and long life are desirable ... up to a point.

The added 5% KOH doesn't make the soap obviously softer IMO, but I concede that's my subjective opinion -- I'm not measuring hardness with a penetrometer.

The benefit of a small amount of KOH for a high palmitic-stearic soap (aka a high percentage of lard or palm) is the lather starts quicker and develops into a nice handful of suds with less scrubbing on the bar. The KOH essentially takes the place of using more coconut oil to get abundant faster lather. The lather of a 5% KOH soap cured for a month or so is comparable to a recipe with maybe 20-25% coconut oil versus my preferred 10%-15%. A 5% KOH soap with lower CO has the benefit of not drying my skin out.

Another way of looking at it is the 5% KOH in a high lard recipe reduces the cure time needed to get the lather quality -- a month or so for 5% KOH versus a year or more for the same recipe with no KOH.

 

[Nanditasr]

... the lather starts quicker and develops into a nice handful of suds with less scrubbing on the bar...The lather of a 5% KOH soap cured for a month or so is comparable to a recipe with maybe 20-25% coconut oil versus my preferred 10%-15%...the 5% KOH in a high lard recipe reduces the cure time needed to get the lather quality -- a month or so for 5% KOH versus a year or more for the same recipe with no KOH.

Thanks; I'm now sold on the idea! And I'll try ammonia instead of KOH -- go where no (wo)man has gone before.

So, I guess, using your "geeky soaper method 2", if the recipe needed 100 grams of NaOH, I will now have to use 95 grams of NaOH and (0.875 x 5 grams) of ammonia? (The 0.875 being 35/40 for the molar weights.)
And I assume we're talking about pure, industrial strength ammonia here, not the store-bought one? (Because the latter would bring it down to 0.875 x 5 grams x 5%, which would be really low.)

 

[DeeAnna]

I have only given advice about using 5% ammonia solution -- the typical cleaning ammonia one can buy at the grocery or hardware store. If you want to use a more concentrated ammonia solution, that is up to you. While it may work well and make fine soap, I am uncomfortable giving advice from afar about using more concentrated ammonia solution, so I am respectfully bowing out of this discussion. This is the second time this year that I've been asked for advice about using unusual additives that carry health risks, and I realize I have to set some boundaries to feel comfortable giving advice at all. My apologies.

 

[Nanditasr]

I have only given advice about using 5% ammonia solution -- the typical cleaning ammonia one can buy at the grocery or hardware store. If you want to use a more concentrated ammonia solution, that is up to you. While it may work well and make fine soap, I am uncomfortable giving advice from afar about using more concentrated ammonia solution, so I am respectfully bowing out of this discussion. This is the second time this year that I've been asked for advice about using unusual additives that carry health risks, and I realize I have to set some boundaries to feel comfortable giving advice at all. My apologies.

Thanks. All this while, I thought that the molar mass of "pure" ammonia was 35, but I separately googled "molar mass of ammonia" and "molar mass of ammonia water", and I found that the latter is 35. So I'll go with the 5% solution.

 

[DeeAnna]

Yes, that's right. You're not dealing with ammonia (NH3), which is a corrosive, toxic gas at room temperature and pressure. Instead, you're dealing with ammonium hydroxide (NH4OH) solution which is a liquid, not a gas.

 

[Nanditasr]

I made a non-CO soap, and I added some ammonia instead of KOH. It's turned out fantastic -- not sure I ever want to use coconut oil again!

 

[ngian]

That is interesting. At what percentage did you use ammonium hydroxide?

I made a non-CO soap, and I added some ammonia instead of KOH. It's turned out fantastic -- not sure I ever want to use coconut oil again!

 

[Nanditasr]

That is interesting. At what percentage did you use ammonium hydroxide?

If the recipe needs 100 grams of NaOH, I now use 95 grams of NaOH and (0.875 x 5 grams) of ammonium hydroxide solution. The solution referred to here is the 5% strength one that is available for household use, I understand.

Edit: To change the term "ammonia" to "ammonium hydroxide" in response to DeeAnna's subsequent post. Also note that my calculations may have been off (if you refer to DeeAnna's post). Anyway, what I used worked for me!

 

[DeeAnna]

If the recipe needs 100 grams of NaOH, I now use 95 grams of NaOH and (0.875 x 5 grams) of ammonia. The ammonia referred to here is the 5% strength one that is available for household use, I understand.

The number 0.875 is the stoichiometric ratio of pure ammonium hydroxide (NH4OH) to pure NaOH. You aren't using 100% NH4OH -- you're using 5% NH4OH. The actual conversion ratio for pure NaOH and 5% NH4OH solution is this --

35.04 / 39.997 X 5 / 100 = 0.044
In other words, 1 gram of 5% NH4OH solution is equivalent to 0.044 grams of NaOH.

To state it another way --
39.997 / 35.04 X 100 / 5 = 22.829
In other words, 1 gram of NaOH is equivalent to 22.829 grams of 5% NH4OH solution.

To go back to your example -- If you reduce the required NaOH weight by 5 grams, you'd need to add this amount of 5% NH4OH solution to make up the difference --

grams 5% NH4OH solution = grams NaOH X 22.829
= 5 X 22.829 = 114.15 g

Please do not just use the word ammonia in this context to avoid confusing other people. It's ammonium hydroxide or ammonia solution. Even you were confused earlier -- why perpetuate this misunderstanding?

 

[Nanditasr]

The number 0.875 is the stoichiometric ratio of pure ammonium hydroxide (NH4OH) to pure NaOH. You aren't using 100% NH4OH -- you're using 5% NH4OH. The actual conversion ratio for pure NaOH and 5% NH4OH solution is this...

Based on posts 43 to 46, I went with the calculation I interpreted and stated in my last post (#49). Anyway, despite the botched-up calculations, it's turned out pretty well. Thanks for clarifying.

Please do not just use the word ammonia in this context to avoid confusing other people. It's ammonium hydroxide or ammonia solution. Even you were confused earlier -- why perpetuate this misunderstanding?

Not so much that I was confused -- I was confusing others by using the term ammonia when I meant NH4OH. Edited.

 

[cmzaha]

Think I shall just stick to dual NaOH and KOH, I really do not think my customers will like seeing Ammonium Hydroxide or Ammonia Solution on their label. That would just take more explaining

 

[DeeAnna]

Okay, here's the straight poop about using 5% household ammonia solution in soap for those who want to try it ... https://classicbells.com/soap/ammoniumHydroxide.html This article is a rough draft, so if you have questions or corrections, please let me know.

@Nanditasr -- I have gotten the impression that you have enough chemistry and math skills to solve this problem, since you were able to find or calculate molar weights and calculate stoichiometric ratios. For that reason I did not provide a full solution because I thought it would be really rude to solve a problem you were clearly working on yourself. Even so, I would have been glad to check your work if you had asked.

 

[Nanditasr]

@Nanditasr -- I have gotten the impression that you have enough chemistry and math skills to solve this problem, since you were able to find or calculate molar weights and calculate stoichiometric ratios. For that reason I did not provide a full solution because I thought it would be really rude to solve a problem you were clearly working on yourself. Even so, I would have been glad to check your work if you had asked.

I'll explain how I arrived at this.

In post 43, I said, "So, I guess, using your "geeky soaper method 2", if the recipe needed 100 grams of NaOH, I will now have to use 95 grams of NaOH and (0.875 x 5 grams) of ammonia? (The 0.875 being 35/40 for the molar weights.)
And I assume we're talking about pure, industrial strength ammonia here, not the store-bought one? (Because the latter would bring it down to 0.875 x 5 grams x 5%, which would be really low.)"

[This calculation works out to what you have stated in post 50, just that I have used 0.875 instead of 35.04/39.997.]

Your reply in post 44 was "I have only given advice about using 5% ammonia solution..." [At this point, I concluded that the calculation applied to the 5% solution itself -- my erroneous interpretation.]

Therefore, my response in post 45 was "...So I'll go with the 5% solution."

Your reply in post 46 was "Yes, that's right."

Hence my conclusion and calculation -- and I have not blamed you you for not checking my work. In any case, I'm happy with the result I got, so I may actually stick with what I worked out, since it requires less NH4OH.

 

[Nanditasr]

Think I shall just stick to dual NaOH and KOH, I really do not think my customers will like seeing Ammonium Hydroxide or Ammonia Solution on their label. That would just take more explaining

Can someone please enlighten me: Is NH4OH any worse on the skin than NaOH or KOH? It seems to have a slightly lower pH. Is it harmful in some other way that we should be worried about substituting 5% of the NaOH with the appropriate* quantity of NH4OH?

(After seeing this post, I am wondering what concerns people may have, and whether I should avoid using it and go look for KOH instead.)

*Actually, I use only about 1/2-2/3 of the NH4OH called for in the substitution formula.