Creating a 'Heat Wave' Look Without Mixing

[SkepticJ]

Last night I experimented with glycerin, putting it in water to get the 'heat wave' look that results from a difference in refractive indexes. I forgot that glycerin is miscible in water, and after a little bit of agitation it all mixed into solution and the effect couldn't be seen anymore.

So I tried putting it in 95% ethyl alcohol. It worked for a time, possibly taking more agitation to mix into solution, but it too completely disappeared.

Is there anyway to prevent the mixing? What can I put the glycerin in that will still result in the look I'm looking for? I tried mineral oil, but the glycerin formed into globules.

I'm doing the video shoot tomorrow, so if there's an answer to my question, I really need it by then.

Thank you.

 

[chemisttree]

Use a hydrocarbon that is less viscous than mineral oil like hexanes.

 

[Borek]

Gradient of concentration resulting in gradient of refractive index is possible only when one of substances dissolves in the other - so either you will end with two saturated phases (no gradient, just the phase boundaries) or one phase (no gradient nor phase boundary). Doesn't look to me like what you want can be done, sooner or later effect you are looking for disappears no matter what substances you are using..

 

[SkepticJ]

I'm not looking for a gradient in the refractive index.

I ended up just using water for the project, but I'm going to try some other hydrocarbons to see if they'll work.

I know something like the effect I'm looking for is possible; I've seen two dissimilar fluids doing the churning heat wave look in a children's toy. One of those fluid-filled flexible balls for tossing around and squeezing.

Where can I find hexane? Paint store? Would kerosene maybe work?

 

[Borek]

I'm not looking for a gradient in the refractive index.

If so, we think about different things. I was under impression you are looking for something like the effect visible here:

What is visible is a result of a gradient of the refractive index, gradient that is an effect of density gradient of the air (not different from what we will see in the solution).

 

[chemisttree]

I'm not looking for a gradient in the refractive index.

I ended up just using water for the project, but I'm going to try some other hydrocarbons to see if they'll work.

I know something like the effect I'm looking for is possible; I've seen two dissimilar fluids doing the churning heat wave look in a children's toy. One of those fluid-filled flexible balls for tossing around and squeezing.

Where can I find hexane? Paint store? Would kerosene maybe work?

Find Hexanes in the paint department of Lowe's or Home Depot. You can also use kerosene. You could also use baby oil and water.

 

[SkepticJ]

If so, we think about different things. I was under impression you are looking for something like the effect visible here:

What is visible is a result of a gradient of the refractive index, gradient that is an effect of density gradient of the air (not different from what we will see in the solution).

Ah, yeah, that is the effect I'm looking for. That same effect was seen in the ball-toy, only it wasn't completely clear. Whatever mystery chemicals they use, they pulled it off.

 

[SkepticJ]

You could also use baby oil and water.

I've done that before, and it's not what I'm looking for. The water just forms into globs on the bottom.

 

[chemisttree]

So you need two that are sparingly soluble that eventually separate?

 

[SkepticJ]

Yes. What can do that, that are both clear liquids?

 

[nismaratwork]

I would consider using Butane... cheap, OTC, but for god's sake, ventilate that room and NO SPARKS.

Mix that with Alcohol for a nice effect.

 

[Borek]

And how are you going to keep butane liquid at room temperature?

 

[nismaratwork]

And how are you going to keep butane liquid at room temperature?

You don't, that's the beauty of it... very "self-cleaning". Besides, if he's going to agitate it, then boiling butane would seem to be a natural choice.

How to extract it?... buy a refill bottle and press down... mind the freezing cold.

 

[nismaratwork]

I'd add... you could just chill your station and draw a partial vacuum. You can then control concentrations fairly easily, and boil off excess to agitate the mixture.

 

[Borek]

Way too dangerous for my liking.

http://en.wikipedia.org/wiki/Flammability_limit#Examples

 

[nismaratwork]

Way too dangerous for my liking.

http://en.wikipedia.org/wiki/Flammability_limit#Examples

Can't say boo to that, it is definitely not safe.

 

[chemisttree]

Yes. What can do that, that are both clear liquids?

I've seen saturated NaCl (aq) and THF do that.

 

[SkepticJ]

I've seen saturated NaCl (aq) and THF do that.

I tried concentrated solutions of salt in water, poured into acetone.

With highly concentrated salt water, I got acentone that became milky with salt. It appears that it comes out of solution and forms flakes of salt that gather on the bottom of the container and stick to the sides. Thick salt rime.

After it had time to settle, liquids became clear. A thin layer of denser liquid formed on the bottom of the container. Fully saturated salt water? Much less than the amount of salt water I poured in.

I tried a number of other concentrations. With very weak salt water I got the heat wave effect, but it quicky mixed into solution and didn't settle out into its own layer again.

I'm out of acetone now, can't experiment anymore for a while.
THF is too expensive for my needs, can acetone work the same way? They have similar properties, so I thought it might work.

 

[nismaratwork]

I keep coming back to Kerosene here... but I realize that's already out.


How about Toluene?

 

[Yanick]

I actually noticed this effect some days ago (because of this thread actually) when using a hot water bath to boil some ethanol (or maybe it was methanol I don't remember). If you get some really clean glassware (one bigger than the other, obviously) you can just fill 1 with fluid A and the second with fluid B and put one into the other. When you look through both beakers, you get that heat wave look. I'm not sure but heating might be required, as that was what I was doing and didn't try to just set it up without the heat.

 

[SkepticJ]

I'll contact some chemical suppliers in my area and see if I can find THF for a reasonable price (i.e. not $70/liter).

Since it does what I'm looking for, it's my best option.

chemisttree, how long did it take for the salt water to settle out of the THF?

 

[SkepticJ]

chemisttree, was the THF you used the kind that is stabilized with BHT, or pure THF?

I won't use pure THF--having an artwork that is subject to unpredictable explosion isn't a selling point. $60/L* is a lot to pay for something that may not work.

Does NaCl react with butylated hydroxytoluene in any way? If the compound is altered, then I would imagine that'd remove its THF-stabilizing property.


*Cheapest I found for stabilized THF. Why's this stuff so expensive?

 

[nismaratwork]

chemisttree, was the THF you used the kind that is stabilized with BHT, or pure THF?

I won't use pure THF--having an artwork that is subject to unpredictable explosion isn't a selling point. $60/L* is a lot to pay for something that may not work.

Does NaCl react with butylated hydroxytoluene in any way? If the compound is altered, then I would imagine that'd remove its THF-stabilizing property.


*Cheapest I found for stabilized THF. Why's this stuff so expensive?

May I use this quote, attributed to you? "I won't use pure THF--having an artwork that is subject to unpredictable explosion isn't a selling point." (SkepticJ)

That's a good one.

 

[SkepticJ]

Sure.

 

[chemisttree]

I'll contact some chemical suppliers in my area and see if I can find THF for a reasonable price (i.e. not $70/liter).

Since it does what I'm looking for, it's my best option.

chemisttree, how long did it take for the salt water to settle out of the THF?

I used it to isolate novel sodium silicates for some POSS work I was doing. I shook it and within 5 minutes had two layers. I wasn't using glycerin. I was using ethanol.

 

[SkepticJ]

What is POSS?

Five min., that's plenty fast for me.

Do you know the answers to my safety-related questions? I don't want this thing blowing up months or years down the line and hurting someone.

Thank you.

 

[chemisttree]

Polyhedral oligomeric silsesquioxanes. BHT and BHA are antioxidants in there to prevent the THF from forming explosive peroxides... which it does do only rarely. If you are concerned, its probably not the best solution to your problem.

 

[nismaratwork]

Polyhedral oligomeric silsesquioxanes. BHT and BHA are antioxidants in there to prevent the THF from forming explosive peroxides... which it does do only rarely. If you are concerned, its probably not the best solution to your problem.

re bolding mine:

Solution...

 

[SkepticJ]

I wasn't using glycerin. I was using ethanol.

How do you get the salt to go into solution in the ethanol? I tried today, and none of the salt dissolved, even with heavy agitation. It wasn't even close to a gram of salt, in at least 50cc of ethanol.

 

[Nemus]

I have noticedthat somewhat surprisinlgly you can see these refractive index whorls in concentrated solutions of polyethyleneglycol solutions. Even old ones in sealed flasks that should be homogenous. My theory is that the selective accumulation of water vapor in the headspace is enough to cause some swirls. High Mw polyethyleneglycol can be bought as a laxative under various brand names. I think the generic name is macrogol.
Liquids that are imiscilble will not give the effect. However, you can get something like it if you match the density of two imiscible liquids. Water + dichloromethane (or even more toxic chloroform) + heptane (less toxic than hexane) would work. Silicone oil + a strong salt solution (sodium chloride may not be soluble enough so CaCl2 may have to be used)may also be an alternative but then I am only guessing.