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federalist

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I didn't want to hijack the current thread on cure time, so I started a new thread.

I'm still very confused about what happens during curing. As DeeAnna pointed out, there are three simultaneous processes: saponification, drying, and the development of a crystalline structure.

The thing that confuses me is the saponification process. My understanding is each triglyceride gets cleaved by NaOH, the Na+ binds with the fatty acids (producing soap) and the OH- binds with the glycerol (producing glycerin). Since the OH- is bound to glycerin, why does week-old soap burn my hands? By this time, shouldn't saponification be complete, thereby consuming all free caustic hydroxide ions?
 

IrishLass

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I think you may be confusing saponification with cure. They are 2 separate processes. Saponification means to 'turn into soap'. That's the macro-process that happened when the water, oils and lye that you mixed a week ago solidified and turned into a substance that now lathers and cleanses, whereas before it did not cleanse or lather at all.

Becoming soap is only the beginning, though. It now needs to hunker down for the second process- the cure- where further micro-chemical reactions take place as the water from the soap evaporates and the soap reacts with the CO2 in the air, etc... These further micro-reactions happen at a much slower pace, but in the end they serve to lower the pH in the soap some, make it milder on the skin, and bring the lather to full maturity.

I'm not a chemist, so I'm not able to give you an technical/chemical explanation of how these things happen, I only know from my 10 years experience of making and using my soap that they do happen. Several others of us long-term soap-makers can attest to the same as well.

Hopefully DeeAnna can help explain more from the chemical side of things.


IrishLass :)
 

DeeAnna

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But lye-heavy soap is only ONE reason of several that may cause irritation. So let's step back and troubleshoot first before deciding your soap has a problem that may or may not exist.

If week-old soap burns your hands, you are (1) sensitive to another ingredient in the soap or (2) you are formulating your recipe incorrectly or (3) you are doing something to seriously sloooowwww down saponification.

I kind of doubt Idea 3 is the problem, but I don't know how you soap, so I'm throwing it out for you to consider.

If that's not the problem, then the next thing to look at is Idea 2. You need to zap test your soap. If it zaps your tongue, then lye heaviness is your problem. Post a complete recipe with weights and your method and let's troubleshoot.

If the soap does not zap, then look to Idea 1. Something else in your formulation that is irritating your skin. The use of coconut oil and/or fragrance are the two culprits I would look at first, based on troubles I've read about that other people have.
 

Susie

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^What they said.

I am in the "something is wrong if it burns you" camp. Please post your recipe in weights so we can troubleshoot.
 

federalist

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It is probably the use of coconut oil since there is nothing special about my recipe. I have been making 100% coconut oil soaps (varying amounts of superfat from 2% to 10%) for use as a household cleaner.

Please let me know if I am getting this straight... Soap shouldn't burn after saponification. However, it continues to become even milder with time due to a curing process that lowers the pH?

IrishLass, you mentioned how soap reacts with CO2. Does that mean that my soap will need to be open to air during curing? So don't wrap it in plastic-film?

Sorry for all the questions! If it weren't for this forum, I don't know if I would have gotten into soap-making. So grateful for your collective knowledge, experience, and passion; you guys rock!
 

The Efficacious Gentleman

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Leave it open and able to air (so not tight together in rows) for at least 4 weeks.

As Susie said - what is the recipe? It might have something that you have overlooked, maybe the scent amount?

It shouldn't burn after it is saponfiied, regardless of pH (pH is a big red herring here) but it can make your skin feel dry or tight.
 

shunt2011

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It is probably the use of coconut oil since there is nothing special about my recipe. I have been making 100% coconut oil soaps (varying amounts of superfat from 2% to 10%) for use as a household cleaner.

Please let me know if I am getting this straight... Soap shouldn't burn after saponification. However, it continues to become even milder with time due to a curing process that lowers the pH?

IrishLass, you mentioned how soap reacts with CO2. Does that mean that my soap will need to be open to air during curing? So don't wrap it in plastic-film?

Sorry for all the questions! If it weren't for this forum, I don't know if I would have gotten into soap-making. So grateful for your collective knowledge, experience, and passion; you guys rock!
Not IL but the answer is correct. Soap becomes better with time. However, if you are just using it for cleaning you can use it as soon as there is no zap. Especially since you are using 100% CO. Your soap needs air circulation to cure. Don't wrap it until it's fully cured or being made into laundry powder.
 

federalist

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Here is the latest recipe. I did not add fragrance, and everything was mixed by hand in a warm water bath (~110 F) to medium trace.
140g coconut oil
24g lye
48g water
 

IrishLass

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I can only speak for myself, but a week-old 100% coconut soap at only a 5% superfat (which, according to your recipe is what you made) would make my hands (and the rest of me) feel quite awful..... and even if it didn't zap and/or was fully cured, it would still feel unpleasant on my skin.

The reason why because of the extreme cleansing power of saponified coconut oil. Of all the oils, it is one of the most cleansing when saponified (so is PKO and babassu), and when used at certain levels in soap with a low superfat, it is able to strip my skin of almost every last vestige of moisture for a time (at least until my skin can bounce back), and it would have nothing to do with excess alkalinity or anything like that. It's just the extreme cleansing nature of saponified coconut oil.

Having said that, I do like to make 100% coconut oil soaps for my body, but only with a 20% superfat. It still cleanses and lathers profusely with a 20% S/F, but the higher S/F takes a lot of the of the bite out of it and it is much kinder to my skin.

If you made the soap for cleaning purposes, I would use gloves to protect your hands.

Ditto what the others said in regards to making sure your soap has plenty of air when curing. :thumbup:


IrishLass :)
 

Susie

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And, wow, your batches are tiny. When batches are that small, very tiny errors in weighing can be magnified. I would strongly suggest at least 500 g of oil/batch sizes.

When you unmold, there is no liquid left? Just making sure due to your hand mixing.
 

IrishLass

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Good catch Susie. I totally missed the size of the batch. My attention was focused too much on the superfat %, wouldn't you know it. lol

Ditto what Susie said, Federalist. When batches are that small, even the smallest discrepancy in weighing can translate into a huge discrepancy because of the nature of lye. Batches as small as that should only be attempted if one has a very sensitive digital scale that can weigh as least as low as .01g/.0005oz with accuracy, because when a batch is as small as yours was, just being 1 gram off in the weight of the lye results in much bigger/exponential consequences than would happen if the batch were bigger. Because of that, I only attempt batches as small as 1 lb. with my regular scale.


IrishLass :)
 

DeeAnna

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If the coconut oil soap is really irritating your skin, yes, your skin could feel like it's burning due to the irritation going on. Usually coconut oil soap just leaves my skin feeling dry and tight, but I only get it on my hands every once in awhile when using a stick of 100% coconut oil soap as a stain treatment. If I used CO soap a lot on my hands, I have no doubt my skin would get red and really irritated.

Again, the way to figure out whether your soap is lye heavy and thus not skin safe or if it is irritating due to the coconut oil ... is the zap test. If you are not willing to do that, you will really not know what the real trouble is.
 
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federalist

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Yes, it could be measuring error magnified by a small batch size (I make chunky individual bars). When I unmold, there is no liquid leftover. I know I should zap-test, but the thought of raw gooey soap on my tongue...

I am probably experiencing both the high cleansing nature of coconut soap and a few bars with leftover lye. But I'm okay with that since these soaps are for cleaning. And wow, they are amazing on dishes!
 

IrishLass

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I know I should zap-test, but the thought of raw gooey soap on my tongue...
I never zap-test until my soap is at least a week or two old, and when I do I just rub a wet finger on my bar to kick up some lather, and then I gently touch the lather to the very tip of my tongue. That's really all one needs to do to conduct a zap-test. If the thought of a little suds on the tip of your tongue squicks you out, you can just keep a glass of water handy and rinse your tongue off in the water.


IrishLass :)
 
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