All sorts of questions...

Does adding a 20% salt solution as a thickener also reverse saponification? The white blobs appear the same as when adding a CA solution.

If not, what then?

Edit: Failor writes:

Glycerin is typically “grained” (separated) out of commercial soap with common salt, then sold as a raw material.

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Is that glycerin separating then? How come it re-emulsifies with waiting? What causes the thickening effect anyway, with salt?

Sapo said:

Does adding a 20% salt solution as a thickener also reverse saponification? The white blobs appear the same as when adding a CA solution.

If not, what then?

Edit: Failor writes:

Is that glycerin separating then? How come it re-emulsifies with waiting? What causes the thickening effect anyway, with salt?

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Hi! Salt doesn't reverse saponification at all.

Looking first at bar soap: sodium soap and sodium chloride are salts that both have sodium as the positive ion in solution. Salt is a much stronger electrolyte in that it dissociates completely into positive and negative ions when it dissolves. This has the effect (called the common ion effect) of decreasing the solubility of the soap. The soap precipitates out of solution and floats to the top of the kettle. That's how it's separated from the glycerin in the boiled method of soapmaking. It's commonly called salting out.

What happens when you add sodium chloride to potassium soap may be more complex, but for whatever reason it seems like it might have a similar effect of reducing the solubility of the soap. This could explain the thickening and the separation. But the better material to thicken liquid soap is potassium chloride. It's obtainable, so we should try it sometime.

Sapo said:

Understood, but wouldn't the partial reversion of the saponification process be apparent, if they actually did it? Their soap is clear and in my tests the "overneutralization" resulted in white floating/blobs of FFAs - which in my tests either float on top, or can be sort of emulsified back into the whole thing by reheating (neither scenario seems to be the case in Dr. B's).

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Well, first let me say that for purposes of discussion I am taking them at their word. They talk about using an acid to change the pH of soap and create a superfat. What they mean by that is unambiguous.

FFAs in liquid soap don't necessarily separate or look cloudy. I have made experimental LS using only fatty acids -- no oil -- and even with a significant lye discount it came out clear as glass. Here is a patent describing that particular technique:

http://www.google.com/patents/US4310433

This also produces a soap with a lower pH. Quoting from the patent:

The ratio of neutralized to unneutralized fatty acids in the compositions herein is from about 24:1 to about 7:1, preferably from about 14:1 to 7:1. Fully neutralized potassium soap compositions, when measured as a 1% solution based on total fatty acids, have a pH of about 10.3. The compositions herein have a pH of from about 8.7 to 9.7 when measured on a 1% total fatty acids solution basis.


Using an acid is preferred when you can get away with it, because oils are way cheaper than fatty acids. The result depends on how much FFA is released and which fatty acids are involved. Some, like oleic acid, are clear liquids. Some are somewhat soluble in the presence of soap. You would want to keep free palmitic and stearic to a minimum (notice what oils they are using for Dr. B's).

What you say makes sense. Sorry for being a hardass, I'm just trying to wrap my head around these things and lacking a chemist's background is getting in the way .

If I was to attempt creating a 0% SF soap, then adding an appropriate amount of CA to achieve 3% SF (more is likely not wise?), when would I add the CA? Confused here again because I fail to see how it would be spread around properly while the soap is in paste stage - so I instinctively assume the correct time to add it is when the soap is diluted. But as explained above, my chemical ignorance makes me make false assumptions, I'd rather ask .

As usual, I greatly appreciate the help.

I've added CA to diluted soap, white blobs appeared, floated on the surface and did not re-emulsify.

I stick blended the whole thing, the FFAs re-emulsified perfectly. Now I know it is possible to make a completely CP-LS, start to finish (including cold dilution), that is superfatted with FFAs, without adding any additional emulsifiers.

My pH strips show, as usual, inconclusive (2 different strips that show 2 different readings) results, but guaranteed lower pH than it's pre-CA master batch. pH 8-9 vs. 9-10.

Phenolphthalein colors to fuschia when applied to the master batch, but stays colorless in the CA batch. Does this mean the pH went under 8.2? Is that even possible? The amount of CA applied was not much, in fact far less than intended.

Does a truly reliable way of testing soap's pH exist, if price isn't a factor?

Sapo said:

I've added CA to diluted soap, white blobs appeared, floated on the surface and did not re-emulsify.

I stick blended the whole thing, the FFAs re-emulsified perfectly. Now I know it is possible to make a completely CP-LS, start to finish (including cold dilution), that is superfatted with FFAs, without adding any additional emulsifiers.

My pH strips show, as usual, inconclusive (2 different strips that show 2 different readings) results, but guaranteed lower pH than it's pre-CA master batch. pH 8-9 vs. 9-10.

Phenolphthalein colors to fuschia when applied to the master batch, but stays colorless in the CA batch. Does this mean the pH went under 8.2? Is that even possible? The amount of CA applied was not much, in fact far less than intended.

Does a truly reliable way of testing soap's pH exist, if price isn't a factor?

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Hi, thanks for reporting your interesting results! I'm sorry that I forgot to respond to the question you asked a while back, but yeah the time to acidify is after dilution, so you did the right thing. Please keep us posted on any other observations you have about the soap such as how it feels and smells and how it reacts to added fragrance.

Funny thing is, you may have actually done the exact thing that Failor was doing. I probably noticed a long time ago and then forgot until someone pointed it out recently, but her recipes seem to assume 100% KOH strength. That cancels out her lye excess if you assume 90% KOH.

Try the phenolphthalein with a 1% solution of paste in distilled water. 8.2 does sound a bit low but who knows. To get the most accurate result I think you would need a properly calibrated pH meter. I've never gotten into that so I can't offer any detailed advice.

This next one is probably a shot in the dark. Not that I'm underestimating your knowledge or anything, it just seems that only a few broke bastards like me and Rosche would ever consider it so the information might not be out there, heh.

In this thread...

http://www.soapmakingforum.com/showthread.php?t=51237&highlight=deeanna+glycerin&page=3

...Rosche talks about substituting glycerin with sucrose due to economical concerns and the similarity of the 2 substances. Any idea if there is any truth to that?

From what I gathered, glycerin provides: better clarity, speedier saponification, better dilution (speed and lesser h2o requirements), aids in sequestering.

Think a 2:1 (or less, that is just the max solubility at 25 centigrade) sugar-water solution for the KOH liquid might achieve some of the same benefits?

Also, while sugar is a preservative in high doses, would it pose a spoil risk if used in lower concentrations?

Yeah, I ask a lot of annoying questions .

topofmurrayhill said:

Funny thing is, you may have actually done the exact thing that Failor was doing. I probably noticed a long time ago and then forgot until someone pointed it out recently, but her recipes seem to assume 100% KOH strength. That cancels out her lye excess if you assume 90% KOH.

Try the phenolphthalein with a 1% solution of paste in distilled water. 8.2 does sound a bit low but who knows. To get the most accurate result I think you would need a properly calibrated pH meter. I've never gotten into that so I can't offer any detailed advice.

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Yeah, I think that was me about the KOH (im)purities. Its confusing because she was literally doing 0 SF all the time and neutralizing for nothing, heh. Unless she had her hands on some 100% KOH.

I assumed 8.2 because after reading up on it, the sources say it only goes colorless under that. Beats me though.

Sapo said:

...Rosche talks about substituting glycerin with sucrose due to economical concerns and the similarity of the 2 substances. Any idea if there is any truth to that?

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There is definitely truth to it in principle. I use sugar as one of the ingredients to make a certain type of non-MP transparent soap. I have only tried it very casually in liquid soap, to help with clarity of a slightly hazy one.

There are several substances typically used as solvents for transparent soap and/or liquid soap. These are alcohol, glycerin, propylene glycol, sucrose and sorbitol. Alcohol can be difficult to work with. Propylene glycol tends to substitute for it and is easier to work with (it's commonly used for MP transparent soap). PG and glycerin in some combination are arguably the most practical ones to facilitate saponification of liquid soap because they are effective, nonvolatile, nonreactive and non-discoloring.

Sucrose and sorbitol are part of this family, and solutions of them have some of the same effects. Normally you see them used in combination with other solvents and typically added at the end to help with clarity. They could plausibly help with saponification when added up front, but I don't know how effective they are on their own, how much you'd need to use or what side effects there potentially are. Experiments are needed, if you feel adventurous.

How to use them is also something to be figured out. KOH may not dissolve in simple syrup, but I've never tried it. My first thought would be to make the solutions separately.

Circumstances under which you might use a preservative in liquid soap can be a matter of personal judgment. It normally doesn't need one, and what would change that isn't always clear-cut. I probably wouldn't do it for soap intended for personal use even if I added sugar.