Lye purity

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Tribe

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I really tried searching the forum before asking my following question (and I am new here so that could be the glitch perhaps), but I did not find any threads fully discussing this topic. Please help if you can--or direct me to the relevant thread(s).

Question. I am trying to research, thoroughly, the lye issue. Specifically how pure a given brand of lye is or is not. Here is an example of a COA from a particular manufacturer that I'm looking into (see attachment for the actual COA).
Sodium Hydroxide (NaOH) Value: 99.21 Unit: %
Sodium Carbonate (Na2CO3) Value: 0.32 Unit: %
Chlorides (CI) Value: 41.29 Unit: ppm
Iron (FE) Value: 3.54 Unit: ppm
Date of production (mmyyyy) 112015
Date of expiry (mmyyyy) 112017

1. What am I looking for? I assume I want the highest amount of Sodium Hydroxide in the batch. Correct?
2. Regarding Sodium Carbonate, Chlorides and Iron: what is their contribution (chemically) to the batch? And therefore, of course, to my bar of soap?
3. Does 100% Sodium Hydroxide not include these 3 ingredients (and the COA will therefore state 100 and NOTHING else on it)? Is that what makes "100%" a food grade Sodium Hydroxide?
4. Is there a chemist's forum or any other resource that might better clarify this information? I know about Kevin Dunn...trying to get his book.

Thank you so very much in advance.

View attachment COA NaOH.pdf
 

Tribe

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Thank you for replying. Do you mean to say then that the 100% sodium hydroxide is NOT 100%, but rather some version of formulation (like this one that I posted)...
But they do claim its 100%. That is my confusion.
 

DeeAnna

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I think you are confusing 100% lye in the sense that the product you buy doesn't contain any other added ingredients vs. the concept of chemical purity. No chemical is perfectly 100% pure. **

You won't ever ever find 100% NaOH, and if you do get the 99.2% lye, it won't be 99.2% for long. This is not analytical chemistry -- it's soap making where consistency is more important than the highest possible purity. NaOH that is plenty good enough for soap making is around 95% purity as made by the manufacturer. If you can get the 99% product for the same price, buy it. If you must pay a premium, stick with the normal tech grade.

How you store lye is far more important as how pure it is to begin with -- you want to keep the lye at very low humidity and you want to minimize introduction of fresh air. Even if you store properly, understand you will reduce the purity of your lye just because you have to open the container to take lye out -- this allows carbon dioxide and water vapor into the lye container.

Carbonates come from lye reacting with CO2 in the air. Your soap will always have a small amount -- either as supplied by the lye or because sodium carbonate is created as the soap cures and reacts with the open air. If you want sodium carbonate (soda ash) as an ingredient in your soap, you'd need to intentionally add it as a separate ingredient. Don't stress over the iron -- it's only a tiny amount and it's an unavoidable part of the manufacturing process.

** ETA: An example might be bottled or tap water. There are always impurities in the water based on where it comes from or how it is processed -- things like trace minerals, dissolved air, possibly residual disinfectant, etc. These materials are not added ingredients intended to alter water into some other product, however. Now if I added sugar and flavoring to make sweet cherry flavored Koolaid drink, for example, it would not be correct for me to call it 100% water.

Another example might be a bag of beans to be used in soup. The beans are 100% beans -- the producer did not mix the beans with rice or barley -- but there can be the occasional stone or stem that are natural "impurities" to be expected in a batch of beans.

Lye can be 100% lye in that it is NaOH without added ingredients, but the NaOH has impurities due to how it is manufactured (trace metals are an example) and due to the essential chemical nature of NaOH -- it is deliquescent (absorbs water very easily) and highly reactive (for example it reacts very quickly with CO2 in air to form sodium carbonate).
 
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Tribe

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Thank you DeeAnna. Very very helpful.

What about this:
1. Would there be/could there be any other impurities in a NaOH batch aside from the current list on this COA? Do you know what they are?
2. Do you know what these impurities actually "do" to the bar of soap (and then therefore--what they can "do" to the person using the soap)? Carbonates, chloride, iron, etc.
3. If no chemical is perfectly 100% pure then HOW are companies able to write 100% on their labels?
4. Can you explain the "food grade" term then? Is that just a marketing ploy?
5. What would 95% purity mean? More of the below impurities or other impurities altogether?
6. Do you have any idea how the manufacturing of the NaOH creates trace metals? Didn't understand what you meant by that entirely.

You're awesome. Really appreciate.
 

DeeAnna

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1. Would there be/could there be any other impurities in a NaOH batch aside from the current list on this COA? Do you know what they are?

You'd have to ask the manufacturer.

2. Do you know what these impurities actually "do" to the bar of soap (and then therefore--what they can "do" to the person using the soap)? Carbonates, chloride, iron, etc.

Do to the person? Nothing. All these materials are found in our everyday environment. Carbonate -> baking soda, washing soda. Chloride -> table salt. Iron -> vitamins, meat.

Do to the soap? Overall if you do not account for the total amount of the impurities, they would increase the superfat, all other things being equal. Carbonates (washing soda) can add a bit of additional detergency (cleaning power). Iron can possibly trigger DOS (rancidity), although calcium (hard water) and copper (water pipes in your home) are the bigger culprits.

3. If no chemical is perfectly 100% pure then HOW are companies able to write 100% on their labels?

I explained that in my previous post.

4. Can you explain the "food grade" term then? Is that just a marketing ploy?

No, it's not a ploy, at least as it is used in the chemical industry. Food grade lye may indeed be the exact came product as non-food grade, but the food-grade product typically has been specifically tested for additional trace impurities that are not allowed in something you eat.

Buying food grade lye to make soap doesn't make any sense to me, but it does to other soapers. YMMV.

5. What would 95% purity mean? More of the below impurities or other impurities altogether?

You need to read the certificate of analysis and/or talk to the manufacturer.

6. Do you have any idea how the manufacturing of the NaOH creates trace metals? Didn't understand what you meant by that entirely.

Trace materials aren't "created" -- they come from somewhere.

One typical source of trace metals comes from the metal pipes, pumps, mixers, and other metal equipment used to manufacture the product. Even you will add trace metals to your soap any time you use a metal spoon or whatnot.

Anything made with ingredients that come directly from nature may contain chemicals that are a normal part of the from-nature ingredients. One way to manufacture NaOH is to use concentrated brine (seawater) pumped from the earth and treat it with electricity to break the brine into useful chemicals including NaOH.
 
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topofmurrayhill

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I am trying to research, thoroughly, the lye issue.
This is the comment that struck me when I read your question this morning. There is no "lye issue" that I know of. What lye issue?

If you would like to understand what food grade sodium hydroxide is, you can refer to the Food Chemicals Codex in which are specified the manufacturing and purity standards for that product. It will cost you several hundred dollars to buy it, because it's only of relevance to chemical manufacturers.

The issue is simple. If you are making pretzels, you buy food grade lye. If you are making soap, it doesn't matter if you use food or technical grade. Some people think it matters or they feel better using food grade, which is fine except for the fact that it doesn't matter one tiny little bit by any stretch of the imagination period.

Surely you understand that nothing is 100% anything. My package of Domino says 100% pure cane sugar. Technically it is not, but commercially and for practical purposes it is. The same is true of salt and baking soda and other things you buy from the supermarket, so it doesn't make much sense for you to worry over it in the case of lye for soapmaking, for which it's irrelevant.
 
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DeeAnna

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"...I don't think you will find this place too fruitful if you are engaged in the popular pastime of scouring the world for toxins to rail about...."

Nice reply up to this point, but this comment is an unnecessary jibe.

Sometimes people Just Want to Know, and that's the strong impression I'm getting from Tribe's questions so far. Maybe Tribe isn't asking in the same way you or I would ask, but the attitude is showing a desire to learn, not the attitude of a closed mind.

I would like to keep the discussion productive and encouraging.
 

topofmurrayhill

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I have read over those posts more than once today and I have concerns about the intent. Next thing you know there will be something going around about the toxins in handmade soap.
 
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Tribe

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topofmurrayhill, hope you're having a beautiful day. And all.
When I said "lye issue" I was referring to the hullabaloo regarding the purity. I want facts. I was not claiming anything or implying false research. Obviously I didn't realize it could be read like that (?).
If you say "food grade" is only of relevance to chemical manufacturers you might not be aware that there are many soapers out there that worship this term. And I would therefore implore you or anyone who likes to know the "other side" of things to look further into it. NOT because you will change your mind, but because sometimes it's wise to understand further.

"Surely you understand that nothing is 100% anything".
I 100% do:)

"The same is true of salt and baking soda and other things you buy from the supermarket, so it doesn't make much sense for you to obsess over it in the case of lye for soapmaking, for which it's irrelevant."
So herein lies my curiosity. WHY it has become an obsession altogether. Perhaps for the same reason many things became an obsession. Some little bird once whispered it to his friend...his friend was a cool dude, people like to listen to him...y'know.
OR because there is some truth to it.
Is it being incessant to just ask?
Thank you DeeAnna.

Yes, to confirm, I like to Just Know. I would say that's a good thing.
 
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galaxyMLP

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The reason that "100% lye" is stressed is because we need to use lye that is not mixed with additional chemicals like metals. "Draino" for example is mixed with metal and I believe some peroxides. You don't want to use that to make soap.

We want people to look for sodium hydroxide with no other additives. However, anything above 90% in PURITY works for our soaps (like for liquid soap when we adjust the purity amount in a lye calculator). I stress purity because I'm referring the the actual sodium hydroxide present in the product by analytical testing.

I think it's good to ask this as it leads to a better understanding of why we do what we do. It's hard to understand the concept of impurities or contaminants because most people don't think in that way.
 
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DeeAnna

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I too have seen the "toxin thing" happen, and I don't like it either. Threads seldom go that direction, however. More often than not, new people just have a lot of burning questions about something they know very little about. They ask, they get answers, and they move on to other matters.

Nothing has been said so far in this thread that shows it is becoming a wrangle about "chemicals". IMO, until it does go there, it's not gone there.
 

galaxyMLP

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Yes, the toxin thing can be annoying but I try to ignore it. People will believe what they want to believe and at a certain point reasoning won't work. I've learned to let it go. My cousin once told me that since I worked in a lab "oh, but you're ok with toxins and all that stuff".

I was going to put what I wrote below in my other post as an edit but it got too long so I'll post it in a new one!

It is easier to tell someone "get 100% lye" without explaining exactly why every time or, going into depth about how the lye you get is not actually 100% pure. Most people would be overwhelmed by this and would not understand the difference between 98% lye with 2% additives and 98% lye that has 2% impurities so it's actually considered 100% lye.

I will also tell you that I highly doubt that for most places tech grade and food grade lye are considerably different. It is based on specifications and sometimes the only difference between 2 grades of something is the analytical work done to prove that it's "good enough". I know because I worked at a chemical manufacturing plant and one of our products had 3 different customers that required different specs with each customer. The one with the highest specs paid the most. Even though the one with the lowest was getting the SAME product, they paid significantly less. There were sometimes that the product failed for one customer but passed for the other so it's not always like that but you get the idea.
 

Tribe

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DeeAnna. Yes, I couldn't have explained myself better. "Burning questions"..."They ask, they get answers, and they move on to other matters."

galaxyMLP. So then it seems people are confusing the word 'additive' with 'impurity'. Meaning, there are natural 'impurities' in EVERYTHING, but what we are concerned about regarding NaOH is that there are no manufacturing additives. We want that all they put in there was NaOH and nothing else.

Edit: galaxyMLP, I wrote this post before I saw your answer:) So I guess I'm getting it then.

Thank you all for your wonderful patience.
 
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galaxyMLP

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DeeAnna. Yes, I couldn't have explained myself better. "Burning questions"..."They ask, they get answers, and they move on to other matters."



galaxyMLP. So then it seems people are confusing the word 'additive' with 'impurity'. Meaning, there are natural 'impurities' in EVERYTHING, but what we are concerned about regarding NaOH is that there are no manufacturing additives. We want that all they put in there was NaOH and nothing else.



Edit: galaxyMLP, I wrote this post before I saw your answer:) So I guess I'm getting it then.



Thank you all for your wonderful patience.

Yay! So glad you understand it. Yep, that's all there is to it!
 

topofmurrayhill

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I suspect it's true that you could make pretzels with technical grade lye and it wouldn't make a difference. On one hand, it's understandable that people might want to stress their use of food grade sodium hydroxide in soapmaking, but perhaps unbeknownst to them it's rather misleading advertising.

Food grade is often not even the purest form of things. On the matter of supermarket items, one spec (may or may not be up to date) for table (food grade) salt states it has to be 97% sodium chloride on a dry matter basis, not including additives, and it can contain:

5. CONTAMINANTS
Food grade salt may not contain contaminants in amounts and in such form that may be harmful to the health of the consumer. In particular the following maximum limits shall not be exceeded:

5.1 ARSENIC - not more than 0.5 mg/kg expressed as As.
5.2 COPPER - not more than 2 mg/kg expressed as Cu.
5.3 LEAD - not more than 2 mg/kg expressed as Pb.
5.4 CADMIUM - not more than 0.5 mg/kg expressed as Cd.
5.5 MERCURY - not more than 0.1 mg/kg expressed as Hg.

Toxic stuff, but poison is in the dosage. Salt is toxic too, and at those concentrations the salt will poison you before the metals do.

A typical analysis of food grade baking soda looks much like that of sodium hydroxide.
 

The Efficacious Gentleman

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That is important to note - just because it is a word that some soapers worship (thankfully this is the first real appearance of anything like that here) doesn't mean it's a worthwhile question at all. Look at meat eaters who want to know if a soap is vegan just because they don't like the thought of 'rubbing a dead animal on my skin' or most of the people asking if the soap is 'gluten-free' - they get in to a mindset and then end up losing the rest of their mind. Gluten-free = good, therefore gluten = bad, therefore a good soap must = gluten-free. For the vast majority of people it really doesn't have to be gluten free, only if gluten affects you topically.

As for the purity, of course they follow the usual route of chemicals = bad. 'There is iron in my soap? I don't want iron in my soap! Mercury? MERCURY? Certainly not!' Never mind that these amounts are mind bendingly low and that in a day they most likely consume more of these things directly than they ever would from soap through the skin. But it becomes the new totem, the trace elements become the new causers of all that is wrong with our health and any soap with them is as bad for you as commercial stuff.
 

Susie

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The hullabaloo over lye purity and food grade is just one more example of the "someone said it, so it must be true" mentality of most people. Most people choose not to ask questions and actually think for themselves. Tribe, you are not most people, thank goodness! We're here to support the folks who ask the questions so they can think for themselves. We love those people!

People who come to spread the current misinformation, not so much. They usually don't last long.
 

Tamijean

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Trying to make soap in the dominican republic

I am able to find 100% lye in the states but in country the best I have been able to find is 95%. it lists 4% as inert ingredients, is this type of lye ok for soaping?
 
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