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Author Topic: Why does salt added to hand-cleaner produce a gum?  (Read 7582 times)

Denis Santerre

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Denis Santerre asked the Naked Scientists:
   
If I take hand sanitiser and add a pinch of salt to it a gum like substance will form. I suspect it may be glycerin.

It is extremely easy to do. Variations are to make a saline solution and add that to the sanitizer. Or to add water to the separated sanitizer and the gummy material will float.

My sanitizer contains  Carbomer, fragrance, glycerin, isopropyl
alcohol,myristate, propylene glycol, tocopheryl acetate,and water.

What's going on?

What do you think?


 

Offline Chemistry4me

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Why does salt added to hand-cleaner produce a gum?
« Reply #1 on: 20/03/2009 01:27:32 »
I just tried it and nothing happened.

My sanitiser contains: alcohol denat., aqua, propylene glycol, acrylates, alkyl acrylate crosspolymer, tetrahydroxypropyl ethylenediamine, parfum, limonene.
 

Offline lancenti

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Why does salt added to hand-cleaner produce a gum?
« Reply #2 on: 20/03/2009 04:13:37 »
I would say polymerization as a result of introducing a good nucleophile (probably sodium salt of one of those things)
 

Offline Slash

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Why does salt added to hand-cleaner produce a gum?
« Reply #3 on: 22/03/2009 02:13:15 »
I have added a video of the separation I had observed.



I should add that I am the one that had asked the question.

It was from my observations with beads, air bubbles and food coloring in hand gel that got me trying other things.
« Last Edit: 22/03/2009 12:01:57 by Slash »
 

Offline Chemistry4me

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Why does salt added to hand-cleaner produce a gum?
« Reply #4 on: 22/03/2009 02:24:33 »
It looks a lot like what went on in this Kitchen Science.
 

Offline Raghavendra

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Why does salt added to hand-cleaner produce a gum?
« Reply #5 on: 22/03/2009 08:54:00 »
Hmm according to me>>>>>

As much as I recommended a careful approach in my previous post, I definitely wasn't advocating throwing your guar out. It definitely has it's uses. Soluble fiber gums (xanthan, guar, cellulose, locust bean) are excellent for promoting smaller ice crystal formation in homemade ice cream. They also add viscosity to the ice cream mix, allowing, in turn, better overrun (air)/improved scoopability. They're also good for stabilizing- salad dressing, as has been previously mentioned.

The one application where I find guar works wonderfully is cheese sauce. A roux stabilized cheese sauce is a bit tastier, but it involves a lot more time/energy. If you want a quick easy cheese sauce, guar will stabilize it nicely/help to prevent it from curdling. You don't need much- the cheese in the sauce does most of the thickening. Also, because of the lack of flavor diluting starch, guar cheese sauce is a lot cleaner tasting/bolder.

Guar is occasionally used in coconut milk to prevent it from separating. I've been experimenting with it in an effort to keep coconut milk from breaking when boiled. So far the results haven't been that great, though. I think the amount necessary for this purpose exceeds what I'm willing to use.

Xanthan has a good synergy with guar. If you turn out to like it, you might want to invest in some xanthan. I always use both.

So,,, keep track
 

Offline Chemistry4me

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Why does salt added to hand-cleaner produce a gum?
« Reply #6 on: 22/03/2009 10:01:15 »
According to you? :)

Please quote your sources next time. 
 

Offline Bored chemist

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Why does salt added to hand-cleaner produce a gum?
« Reply #7 on: 22/03/2009 11:14:40 »

The original post makes it quite clear what he is talking about.
"My sanitizer contains  Carbomer, fragrance, glycerin, isopropyl
alcohol,myristate, propylene glycol, tocopheryl acetate,and water."
So, no guar gum, and therefore no reason to go on about the properties of guar gum.
Anyway, the most likely candidate for the gum is the "carbomer"- most of the other ingredients are liquids. Most gums are polymers and the carbomer is the only polymer on the list. A lot of gum-like polymers disolve in water but not in salt water.
the polymer is able to dissolve because there are atractive forces betweeen the polymer molecules and the water molecules. Adding a lot of salt means that a lot of the wtaer is "trapped" as the water of hydration of the sodium and chloride ions. with less free water the polymeric gum won't dissolve any more.
It's similar to this
http://en.wikipedia.org/wiki/Salting_out
 

Offline Slash

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Why does salt added to hand-cleaner produce a gum?
« Reply #8 on: 22/03/2009 12:30:43 »
When I read about salting out I discovered why I got slightly different results. In the video I used more salt than I would usually had used. The solution never cleared like I had expected it.
 

Offline Raghavendra

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Why does salt added to hand-cleaner produce a gum?
« Reply #9 on: 23/03/2009 10:50:52 »
According to you? :)

Please quote your sources next time. 

    Hmm nice game haaa
 

Offline mad scientist

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Why does salt added to hand-cleaner produce a gum?
« Reply #10 on: 30/06/2009 15:46:09 »
Just found this forum. Looks interesting.

Your question is an easy one. You hand sanitizer most likely contains 70% isopropyl alcohol. Your other ingredients are:

My sanitizer contains  Carbomer, fragrance, glycerin, isopropyl
alcohol,myristate, propylene glycol, tocopheryl acetate,and water.

I think you missed one of the ingredients. There needs to be a base to neutralize the carbomer.
When using higher levels of alcohols, the polarity of the water/alcohol changes. It becomes more nonpolar that straight water alone.
That being said, you then need to make a salt of the carbomer, (polyacrylic acid)that is more hydrophobic so the carbomer will swell in that water/alcohol solution.
A NaPAA (sodium salt of polyacrylic acid) can only swell in a solution containing about 20% alcohol. TEAPAA (triethanolamine salt of polyacrylic acid) can swell in a solution containing up to 60% alcohol. AMPPAA (aminomethylpropanol salt of polyacrylic acid)can swell in a solution of up to 80% alcohol and so on.....
When you added the salt, NaCl, you formed a sodium salt of polyacrylic acid and and thus the NaPAA cannot swell in a solution of that high amount of IPA and ABC gum as I call it forms (already been chewed).
Some cheaper versions of hand sanitizers on the market will show "pilling" when rubbed on the skin. The salts on your skin, especially if sweating, will form these sodium, potassium and calcium salts and will pill.
 

Offline Chemistry4me

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Why does salt added to hand-cleaner produce a gum?
« Reply #11 on: 01/07/2009 04:55:08 »
Hi mad scientist,
Welcome! Thank you for making it here. :)
 

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Why does salt added to hand-cleaner produce a gum?
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