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Author Topic: Can you help me find the perfect chemical?  (Read 1744 times)

Offline ioftd

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Can you help me find the perfect chemical?
« on: 13/06/2014 00:49:25 »
I am looking for a liquid that needs to have some pretty specific characteristics.  It needs to be clear, have a specific gravity of at least 1.15 to 1.2, have a low surface tension and be relatively safe and non-toxic to be working around.  Right now I am using pure glycerin, but the relatively high surface tension has been a problem. Perhaps a certain sulfactant would reduce the surface tension without changing the other properties of the glycerin?

I am basically using the glycerin to support another liquid and then pulling an object vertically through both liquids. My problem is that the surface tension at the interface between the liquids causes the glycerin to be pulled up into the other liquid, then suddenly that tension will break and the upper liquid will flow back in an uncontrolled way.  I want to eliminate or at least reduce the tension that is causing the glycerin to be pulled upwards along with the object.  Like I said I'm open to some kind of additive to the glycerin or a completely different chemical, but I am introducing this stuff to a studio full of people and lacking most lab safety equipment so it has to be safe and non-volatile.  I've found a few other chemicals that seem to fit the bill but they always seem to be highly corrosive or toxic or flammable.

I have little-to-no background in chemistry or physical science but have been trying to do some research for this project so I may be misusing or misunderstanding some of these concepts and terms, so please correct me if I'm off base.
Thanks!

[MOD EDIT - Please phrase subjects as questions in line with AUP]
« Last Edit: 13/06/2014 09:22:22 by Georgia »


 

Offline chiralSPO

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Re: Help me find the perfect chemical!
« Reply #1 on: 13/06/2014 09:01:31 »
What is the other liquid? Presumably you do not want them to mix ("interface")? Is the density requirement just so that it is denser than the upper liquid, or is there an absolute requirement? What other materials are involved in the system? (wouldn't want to dissolve or react with you container or the objects being pulled through the liquids...)

Given your stated requirements, (and the fact the glycerine works, I am assuming that your top liquid would not mix with water), my first thought is to make a solution of salt water (you can adjust the salt content to get the desired density without getting anything nearly as sticky as glycerine)
« Last Edit: 13/06/2014 09:04:40 by chiralSPO »
 

Offline chiralSPO

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Re: Can you help me find the perfect chemical?
« Reply #2 on: 14/06/2014 00:31:03 »
Oh, and if salt water would satisfy your requirements, and absolute clarity (transparency) of the solution is a must, don't use table salt (which contains silica and starch and possibly other anti-caking agents that would make for a cloudy solution) go for sea salt or kosher salt or rock salt, all of which should be completely soluble.
 

Offline ioftd

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Re: Can you help me find the perfect chemical?
« Reply #3 on: 14/06/2014 01:00:42 »
The other material is an acrylic monomer.  It does not mix with water but has a specific gravity around 1.1 an it needs to float on top of whatever liquid is below.  I have tried using a salt water solution, but the problem is actually made much worse, probably because of the higher surface tension of water. I have tried using vibrator from a torn apart xbox controller, hoping to break that tension but that didn't really help.  Now I'm looking at ultrasonic vibration, but since that is commonly used for emulsifying things and I definitely don't want an emulsion of these liquids, I probably wont spend the money on that equipment unless I'm sure it will help.
Currently I'm trying to use hand soap as a sulfactant in both the salt water and the glycerin, but it takes quite a while for the mixture to settle and become clear before I use it, so I haven't actually gotten to test it.
Thanks for the reply!
 

Offline chiralSPO

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Re: Can you help me find the perfect chemical?
« Reply #4 on: 22/06/2014 17:15:07 »
You might also have luck with a fluorinated hydrocarbon liquid. Some of these are commercially available from companies like 3M. You can expect a high density (something like 1.8), and good clarity. They are non-toxic (as far as we know), but are known to be ozone depleting and persistent environmental pollutants, so you can't just throw it out. I don't think they would mix with the acrylic monomer, and even though their density and surface tension is fairly high, the liquids are unlikely to stick to whatever you're passing through (think of it as liquid Teflon), so I don't think you would have the trailing problem.

I will keep thinking about this problem, but tell me: What are your objects made of?
 

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Re: Can you help me find the perfect chemical?
« Reply #4 on: 22/06/2014 17:15:07 »

 

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