Why oh WHY???

[The Efficacious Gentleman]

Once we eliminate the tests that make no sense, we will be left with ones that tell us something.

Ph- as discussed, only tells us the pH, not if there is excess lye. Not all soaps have the same pH, so it is not helpful without testing a known safe batch of a recipe to have a benchmark for future use. For that, we need an initial safety test.

Pheno - also a pH indicator, not a lye-detector. A well made soap with no excess lye could be in the pink ranges or even the higher pink ranges and still be safe - there are perfectly safe soaps with 12.5pH readings, so pheno would give us a false positive there. It again falls in to the trap of needing an initial benchmark to be even close to useful.

There is a chemist method of testing, but as I couldn't even begin to explain it, there is no way I could see myself doing it regularly. It would actually give us the answer, but is not practical.

That leaves zap testing. Variations in mouth pH aside, the easiest and surest method of testing for excess lye.

While you might not agree with zap testing, the first two points are not actually opinion - strips and pheno are pH indicators which do not, on their own, tell us if a soap is safe or not.

 

[commoncenz]

Interesting older article from Millersoaps.com wherein she tested a commercial soap and two of her handcrafted soaps using a pH meter and various types of pH strips. I'll leave it to you all to debate the conclusions etc. However, there were some interesting takeaways (to me):

1. Anyone expecting all soap to be "safe" at a ph reading of 7 is being overly critical/cautious as generally accepted research has suggested that a pH of 9.5 - 10 is normal for soap.

2. Apparently surfactants can throw off the indicators of some pH strips by as much as 2-3 units.

3. There is variation in pH readings depending on which type/manufacturer of pH strip you use.

It's early in the AM here and I haven't slept well, so I will reread the article after I get some sleep. Might even do a little more reading on the subject. But it seems to me that if a pH meter is the most accurate tool for measuring pH, those who are advocating that no soap is safe unless it has been pH tested as such should spare no reasonable expense in making sure that they have a pH meter.

Edit: I really was suffering from restless sleep. I forgot to add the link this morning.

http://www.millersoap.com/phtome.html

 

[notapantsday]

I don't think our skin cares whether there is excess lye or whether the soap just happens to be very basic by itself. What's important is the pH value. As long as it is diluted enough, NaOH is not a problem.

Besides, what really happens when we dissolve soap in water? Soap is a salt of the fatty acids (FA) and sodium (Na), so when they dissociate we get Na⁺-ions and FA⁻-ions. Some of the FA⁻-ions bond with free H⁺ from the water (autoprotolysis) and turn back into undissociated fatty acids. What remains when more and more H⁺ are removed from the water? OH⁻ of course.

So in the end, we have Na⁺ in the water just like we have OH⁻. Which is the same result we get when we dissolve NaOH in the water. It really shouldn't make a difference whether there is NaOH left in the soap or whether it just happens to be basic because it is soap.

I don't think we need a test specifically for residual NaOH, we just need to test the pH.

Agreed, so what do you suggest for testing?

I think there's nothing wrong with phenolphthalein, you seem to have good experience with it.

 

[The Efficacious Gentleman]

Again, I have to ask what is a good pH and what is a bad pH? What is safe and what is unsafe? Is it always the same for different recipes?

If not, then what does pH actually help with?

 

[notapantsday]

I can't really speak from experience since I'm rather new to soaping but I'd say pH is just one of many factors. There are pH levels that are definitely unsafe (14 or higher) and there are levels that are definitely safe (7-8). But there's a grey area, where other factors like skin type, superfat, oil composition or exposure time should be important too. That's how I would explain that are soaps that appear to be safe at pH 12, while others are very aggressive at pH 10.

If your soap is at pH 8, you know it's safe. That would be a good reason for pH testing to me.

 

[The Efficacious Gentleman]

But the biggest problem with that is that a soap can have a pH of 9 and still be totally safe, based on the recipe. So it will never read 8, it is impossible for it to do so.

Safety of soap is not based on the pH and your skin type or anything like that. Soap suitability, comfort and so on would be, but safety not.

 

[Susie]

I don't need to know the pH of my soap to know if it is safe. I need to know whether there is free lye or not. I zap test now, and I will zap test until I stop making soap. If you folks feel like you need to meet certain pH "guidelines", well, just have at. I am not going to get rid of perfectly good soap just because it does not reach a certain pH.

 

[Sphynxbabies]

We have a responsibility to rule out risk. Phenol helps to rule out that factor. I've never said 'don't zap test' I've simply said it's time to quit pretending that because you are only selling in small farmers markets or a few local stores that Liability does not apply to you. I've said "test your soap" zapping alone is not acceptable. I've mentioned that I have tested soaps from the Festival Entries that have turned bright fuchsia and the they also tested highly positive to the tongue. I have also mentioned that I have tested soaps from the Entries that turned bright fuchsia but did not test positive to the tongue. Soaps that test anything but clear are disqualified. It is a National Festival with entries from coast to coast and to become a Juror for the Soaps and Toiletries Category you are required to test with Phenol. So if a Festival with 40,000 visitors, and a bank of Lawyers require Phenol as a critical part of the criteria for testing, attention should be paid. Is it possible on the soaps that don't zap, that the high PH reaction is to another completely benign ingredient combination, I suppose it could be. Am I willing to stake everything I own on bars that 'don't' zap, blindly believing they are neutral, based on licking a bar? I am not. I have worked with Karl Lagerfeld, Ben & Jerry's Ice Cream, done soap for Oprah, and more. Heightened awareness of liability grows exponentially when you move into these markets, but your risk of liability is no less than mine. In Farmers markets here, there is an 'assumed risk" that the consumer bears when buying product acknowledging that the products you are buying are hand made. I would double check where you are that this is correct for your area. But the minute you place your products in retail stores, that ship has sailed. And to Commoncenz: I think I remember that article. Old but still relevant. And that is my point exactly, if you are not willing to do everything that you can to rule out risk in your soaps, you have no business selling soap.

 

[DeeAnna]

Now that I know you're using phenolpthalein on solid bar soap, I'll be quite frank. There are no, zero, nada standardized tests used by soap chemists that evaluate the excess alkalinity of soap like this. The supposed testing of pH using phenolpthalein indicator on solid bar soap is the handcrafted soapers equivalent of reading tea leaves in the bottom of a cup to accurately predict someone's future. If this is the gold standard used by festival jurors, I am not impressed.

Soap chemists use an acid titration of a dilute soap solution to determine free alkalinity (excess lye). THIS is the gold standard that should be used by any organization or event representing itself as an impartial and accurate judge of soap quality.

Any pH measurement, whether with phenolpthalein, test strips, or a meter -- is only valid and accurate in dilute solutions, not in concentrated solutions (dampened soap) or solid materials (dry soap). You would flunk a Chemistry 101 lab on pH measurement by telling the lab instructor that, "...dilution is a must even though it can weaken the results...."

Measuring the intensity of color visually is a highly subjective test. It is strongly dependent on the lighting intensity, background texture and color, thickness and transparency of the fluid being evaluated, the person's eyesight, etc. When chemists DO use a visual determination of color for a particular test, they use a standardized equipment and procedures and compare the unknown against calibrated visual standards.

But what is most important, even if you insist on using this kind of test -- the fact remains that using a set pH to determine whether a soap is safe or not is wholly inaccurate. It totally overlooks the fact that soap pH depends on the fatty acid content of the soap. Pure oleic soaps and stearic soaps have the highest pH of 11.2 to 11.4. The other soaps -- myristic, lauric, palmitic, linoleic, and linolenic -- have pH values in the low to mid 10s. Source: Dunn, Kevin. Scientific Soapmaking. 2010. If all of the lye has been perfectly reacted leaving no excess alkalinity in any of these soaps, phenolpthalein in a dilute solution of these soaps WILL ALWAYS show pink.

Why phenolpthalein sometimes is colorless, light pink, or dark pink on solid bar soap, whether dry or damp, strongly depends on the crystalline and colloidal structure of each particular soap every bit as much as it does on the presence or not of any free alkali in that soap.

Important safety note:
Do not call phenolpthalein by the nickname "phenol". Phenol is a seriously deadly poison and is not remotely the same as phenolpthalein. This is far worse than using the nickname "glycerin" as a shorthand for glycerin soap or melt and pour soap. If you must abbreviate, at least shorten it to pheno or phenol-p or, better yet, use the chemist's nickname of phph.

Other reference material:
Fischer, Martin. Soaps and Proteins: Their colloid chemistry in theory and practice. 1921.
Spitz, Luis. Soap Manufacturing Technology. 2009.

 

[Sphynxbabies]

Happy Zapping!

 

[The Efficacious Gentleman]

I'm just going to leave this here, because frankly I have much better things to do than repeat myself time and time again.

Pheno can be pink in ranges that are perfectly safe for soap. Clear with pheno does not mean the soap is unsafe, it just means it's got a pH more than 8. That is not a bad thing, soaps can have that and be fine. A soap can have a pH of 11 and be fine. 12 - still safe and good to use.

The pH alone does not tell you if a soap is safe. Pheno alone doesn't tell you is your soap is safe.

You reject soaps based on a flawed basis. That is utterly shameful.

 

[Susie]

1. I live in the USA. I do not have to follow Canadian guidelines.
2. I do not sell my soap. I zap test my soap to determine if it is safe for my skin and my family's skin.
3. I would like to see your sources for scientific standards of safety. NOT your government's regulations, actual scientific documentation. Governments are well known for completely unnecessary regulations in many cases. If you can prove your information and methods using information from actual scientists, then show us.

 

[notapantsday]

I repeat myself, but I'm pretty sure that the assumption that "free lye" is in some way inherently dangerous, independent from the pH level, is wrong.

As I said: when you dissolve pure soap in water, you end up with Na⁺ and OH⁻ in the solution, even if there was absolutely no NaOH left in the (dry) soap. The amount of OH⁻ in the solution directly corresponds with the pH value and it doesn't make any difference whether it comes from NaOH or from soap/self-ionization of water.

or, better yet, use the chemist's nickname of phph.

Am I the only one who had to laugh trying to imagine how they pronounce it?

"So, what kind of indicator would you recommend?"

"ffffffff"

 

[DeeAnna]

"... I repeat myself, but I'm pretty sure that the assumption that "free lye" is in some way inherently dangerous, independent from the pH level, is wrong...."

I don't know why you are thinking this. "Free lye" in a soap IS dangerous. I have no interest in injuring anyone's skin, including my own, and "free lye" will do exactly that. From what you've said earlier in this thread, I get the impression you may be confusing the idea of excess alkali (free lye) with the idea of the intrinsic alkalinity of a salt of a weak acid. That is the same confusion that leads people to use pH strips or phenolpthalein drops to "test" for pH and make the "common sense" assumption that any high pH result = excess alkalinity (free lye).

 

[Susie]

I repeat myself, but I'm pretty sure that the assumption that "free lye" is in some way inherently dangerous, independent from the pH level, is wrong.

As I said: when you dissolve pure soap in water, you end up with Na⁺ and OH⁻ in the solution, even if there was absolutely no NaOH left in the (dry) soap. The amount of OH⁻ in the solution directly corresponds with the pH value and it doesn't make any difference whether it comes from NaOH or from soap/self-ionization of water.



Am I the only one who had to laugh trying to imagine how they pronounce it?

"So, what kind of indicator would you recommend?"

"ffffffff"

I think we are having a difference of opinion on the definition of "free lye", rather than the concept. When I refer to "free lye", we are referring to actual lye crystals or lye water remaining in the soap after saponification. This happens when someone; mis-weighs oils, lack of getting to actual trace during stickblending and the fats separate back out, overheating of soap that leaves lye water in pockets in the soap. This type of "free lye" is, indeed, dangerous to bare skin.

If I am wrong in thinking this, please tell me. I am not trying to disagree with you, just trying to clarify.

 

[Sphynxbabies]

It just seems strange to me that given so many of you over the years have said 'I wish I could make a living selling my soap' that when given an opportunity to talk with someone who has successfully accomplished exactly that, and supports what you are doing, that you are more intent on disproving a method of testing than considering it. Short attention spans aside, Phenol is a proven Ph indicator and is a beneficial aid in the assessment of whether a soap is lye heavy. It is not me you have to be concerned about but the impending regulatory bodies that are already in motion. You will be required I'm sure as we are here in Canada to register each variation on a soap recipe. If there is an incremental value or a diminishing value of an ingredient, the new variation must be registered as a new 'recipe'. the weights, ingredients and all of your information are registered and you must submit to inspection of your bars. No one will be exempt. Is it a pain...totally but if you want to play in anything other than flea markets and farmers markets then you have to step up. If you believe that zap test alone is sufficient, I wish you well. If Phenol testing even removes one caustic bar from the marketplace it is worth it. I never intimated that it was conclusive, I said so in previous posts in this thread. All I have said is we need to insure public safety and our own liability. There is no possible way to test conclusively without a laboratory controlled assessment which is simply not available to us, but we have to do what we can.

 

[Susie]

OK, so you can't prove your information.

We need to at least clear up one thing:

phenol
Also found in: Dictionary/thesaurus, Encyclopedia, Wikipedia.
phenol [fe´nol]
1. an extremely poisonous compound, used in dilute solution as an antimicrobial, anesthetic, and antipruritic. Ingestion or absorption through the skin causes symptoms including colic, local irritation, corrosion, seizures, cardiac arrhythmias, shock, and respiratory arrest. Phenol should be properly labeled and stored to avoid accidental poisoning. Called also carbolic acid.
2. any of various related organic compounds containing one or more hydroxyl groups attached to an aromatic carbon ring.
phenol coefficient a measure of the bactericidal activity of a chemical compound in relation to phenol. The activity of the compound is expressed as the ratio of dilution in which it kills in 10 minutes but not in 5 minutes under the specified conditions. It can be determined in the absence of organic matter, or in the presence of a standard amount of added organic matter.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
phe·nol (fē'nol),
Hydroxybenzene; an antiseptic, anesthetic, and disinfectant; locally escharotic in concentrated form and neurolytic in 3-4% solutions; internally, a powerful escharotic poison.
Synonym(s): carbolic acid, phenyl alcohol
Farlex Partner Medical Dictionary © Farlex 2012
phenol /phe·nol/ (fe´nol)
1. an extremely poisonous compound, C6H5OH, which is caustic and disinfectant; used as a pharmaceutic preservative and in dilution as an antimicrobial and topical anesthetic and antipruritic. Poisoning, due to ingestion or transdermal absorption, causes symptoms including colic, local irritation, corrosion, seizures, cardiac arrhythmias, shock, and respiratory arrest.

VS

Phenolphthalein
Chemical Compound
Phenolphthalein
Phenolphthalein is a chemical compound with the formula C20H14O4 and is often written as "HIn" or "phph" in shorthand notation. Phenolphthalein is often used as an indicator in acid–base titrations. For this application, it turns colorless in acidic solutions and pink in basic solutions.

en.wikipedia.org

Also, using your reasoning, if we lock up everyone who could possibly ever commit a crime, then it is worth it...rather than proving that THIS person committed THAT crime. You are using flawed methods to judge the safety of a soap. And people depend on selling those products to make a living!

 

[notapantsday]

I think we are having a difference of opinion on the definition of "free lye", rather than the concept. When I refer to "free lye", we are referring to actual lye crystals or lye water remaining in the soap after saponification. This happens when someone; mis-weighs oils, lack of getting to actual trace during stickblending and the fats separate back out, overheating of soap that leaves lye water in pockets in the soap. This type of "free lye" is, indeed, dangerous to bare skin.

Oh, ok. I think this really is a misunderstanding, then. I always assumed that the lye is evenly spread within the soap. But of course, if there are crystals or pockets of concentrated lye in the soap, it can be very dangerous no matter what the "average" pH of the soap is. I didn't think of that.

 

[The Efficacious Gentleman]

And also with the fact that 100g of one soap can need more or less lye than another to saponify based simply on the oils (which is why we can't just swap one oil for another at will without knowing if the lye amount changes) so a 1% solution of one soap can indeed have more 'lye' than another - it doesn't mean that one is less safe just because it has more lye.

 

[DeeAnna]

"...There is no possible way to test conclusively without a laboratory controlled assessment which is simply not available to us..."

I agree that most average soapers don't have the ability nor interest to do an acid-titration test for free alkalinity. That is no excuse, however, to use alternative tests that have no valid scientific basis for determining whether a soap really has excess lye or not.

It is absolutely NOT acceptable for festival judges to be determining the quality of contestants' soaps with phenolpthalein as it is used by handcrafted soapers. A nationwide competition should be using a valid, accurate method to determine of free alkalinity (lye heaviness).

Kevin Dunn explains how to do a non-chemist's version of the free alkalinity test in his Scientific Soapmaking book -- see chapter 15. This method can be done in anyone's kitchen with chemicals commonly available to soapers and with some determined, careful practice.

For official versions of this test as used by the soap making industry, refer to the "Official Methods and Practices of the AOCS" (American Oil Chemist's Society) or "ASTM D 460-91, Standard Test Methods for Sampling and Chemical Analysis of Soaps and Soap Products."