Vinegar as lye water?

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gigisiguenza

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I was reading a post on a FB group about using vinegar as lye water and it struck me as counterintuitive - wouldn't the vinegar neutralize the lye?
 

The Efficacious Gentleman

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It would indeed, so you account for that in the calculation.

How much lye will the water replacement neutralize + lye amount I need for my oils = total lye amount.

It's similar to using the more lye when you add citric acid to create sodium citrate, but more so. Of course, the reaction with vinegar would be very strong. What would the purpose be?
 

gigisiguenza

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It would indeed, so you account for that in the calculation.

How much lye will the water replacement neutralize + lye amount I need for my oils = total lye amount.

It's similar to using the more lye when you add citric acid to create sodium citrate, but more so. Of course, the reaction with vinegar would be very strong. What would the purpose be?
According to the OP, they're using it to bring out the color in a natural colorant. Similar to adding indigo to lye solution makes it show blue the best. If I understood it correctly, the colorant needs a high alkaline to really show a nice vibrant red pink that holds up during cure.
 

gigisiguenza

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That's why I'm confused LOL lemme find the post

The question asked was regarding Chinese Rhubarb and using it in vinegar as your lye water.
The response was that since the lye will be a lot stronger than the vinegar, and the rhubarb needs an alkaline pH to turn red, that they think it will work well because they have used vinegar for lye water and it d not seem to affect the lye.

ETA my confusion is based on 1) I assumed since lye is neutralized by vinegar, there would need to be some compensation to do this and not throw all the saponification off, resulting in a major jump in the SF percentage, and 2) why wouldn't it just make sense to throw the rhubarb into the lye directly, same as you do with indigo, to achieve the same thing - blooming the color through the alkaline reaction before adding to the oils so the color holds true.
 

The Efficacious Gentleman

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Unless their rhubarb is suspended in vinegar or something, I don't see why it would be needed - as you say, if it needs the alkaline environment then just add it to the lye water. Unless............could it be to avoid it reacting with the lye itself? Sodium Acetate (the result of lye and vinegar) has a pH of 11 at a 1% solution. So you get your alkaline environment with no active lye.

That is then next to impossible to manage when making soap as the colour will always have to come in to contact with active lye unless you use it in HP.
 

gigisiguenza

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And this is why we tell people to stay away from facebook groups. Vinegar will neutralize lye and its not alkaline, its acidic. Whoever is planning this soap doesn't seem to understand basic chemistry.
Nor does the person giving the advice apparently

Unless their rhubarb is suspended in vinegar or something, I don't see why it would be needed - as you say, if it needs the alkaline environment then just add it to the lye water. Unless............could it be to avoid it reacting with the lye itself? Sodium Acetate (the result of lye and vinegar) has a pH of 11 at a 1% solution. So you get your alkaline environment with no active lye.

That is then next to impossible to manage when making soap as the colour will always have to come in to contact with active lye unless you use it in HP.
TEG actually I think it just needs the alkaline to react, just like indigo.

Obsidian I've seen pics of the resulting color and it's gorgeous, and I'm sure the natural colorants guru in that group will pop up and correct them very shortly (it's actually a really nice group with pretty reliable info, thanks to experienced admins I presume). But when the newbies post with inaccurate info, I just gotta come back double check it here LOL.
 

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I left that group when I read that. I just don't have the time or the patience anymore to deal with those folks.
 

gigisiguenza

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I left that group when I read that. I just don't have the time or the patience anymore to deal with those folks.
Susie I think what irks me is that the person who responded to the OPs question was vague on the yes or no, simply stating they had used it themselves and seen no impact on the lye. What kind of soap is she producing if she sees no difference. Why? Because it didn't blow up? I'm a firm believer in if it involves mixing dangerous substances, I wanna know what the heck the chemistry is before I do it. Check, it took me months to get brave enough to mix lye solution LOL.

And I'm greatly concerned that the OP took that singular response, as vague as it was, and said "ok, it's safe, guess I'll try it", without an ounce of questioning.

I love the info on natural colorants and unusual usage methods I get there, but lordy I have to avoid reading a lot of stuff.
 

DeeAnna

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".. the person who responded to the OPs question was vague on the yes or no, simply stating they had used it themselves and seen no impact on the lye...."

Arrgh! Facebook chemistry for CP and HP soapers seems to be based on "If I don't see any obvious change, then nothing bad really happened" And don't get me started on FB chemistry for Liquid soapers.

When used in soap, 1 oz (28 g) of commercial grocery store vinegar (5% acetic acid by law in the US) will neutralize 1 g NaOH. 1 oz (28 g) of commercial 5% vinegar neutralizes 1.4 g KOH.

If I substituted vinegar for all of the water in my favorite soap recipe and didn't compensate for the lye consumed by the vinegar, then the superfat will go up by about 7%. Is that bad? Or is that good? Depends. In a liquid soap, that much superfat would be a mess. In a bar soap, the higher superfat might result in an overly soft soap that doesn't lather well and is possibly more prone to rancidity.
 

dianaabuela1

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It would indeed, so you account for that in the calculation.

How much lye will the water replacement neutralize + lye amount I need for my oils = total lye amount.

It's similar to using the more lye when you add citric acid to create sodium citrate, but more so. Of course, the reaction with vinegar would be very strong. What would the purpose be?
who much % of the lye ?
 
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