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Topic: Can I somehow dye or color a liquid that is insoluble in water?  (Read 4884 times)

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Offline GreedyBusinessMan

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I would like to make a mixture of two immiscible (insoluble) liquids -- like oil and water. The point, however, is to use two contrasting colors for a visual display.

Ideally, the less-dense liquid would be colored or dyed black, while the other, denser liquid would be of a lighter color.

My first thought is to use some form of petroleum. I know there are oil dyes used in engines, but I'm not sure if those would also spread to water if mixed.

In any case, it would just be nice to have a very dark surface liquid suspended above some water or other bright/clear liquid.

Thanks!

Offline GreedyBusinessMan

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Re: Can I somehow dye or color a liquid that is insoluble in water?
« Reply #1 on: June 18, 2018, 08:37:36 PM »
A friend suggested that I dye the water heavily and use Carbon Tetrachloride as the denser liquid. Seems reasonable to me.

Offline Babcock_Hall

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Re: Can I somehow dye or color a liquid that is insoluble in water?
« Reply #2 on: June 18, 2018, 08:48:03 PM »
Carbon tetrachloride is a bit toxic.  Other chlorinated compounds (chloroform or preferably dichloromethane) are also more dense than water is.  There is a substance that gives water a blue color that makes visualizing immiscible systems easier, but its identity has slipped my mind for the moment.

Offline GreedyBusinessMan

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Re: Can I somehow dye or color a liquid that is insoluble in water?
« Reply #3 on: June 18, 2018, 11:22:40 PM »
From what I've read, a lot of these chlorinated compounds are typically used as solvents.
Do you think this might become an issue when trying to seal off the system with traditional methods like caulk and other silicone sealants?

Offline Enthalpy

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Re: Can I somehow dye or color a liquid that is insoluble in water?
« Reply #4 on: June 19, 2018, 08:47:10 AM »
Do you need a liquid as the upper layer?

Balls of dark-dyed plastic may be easier. Some polymers float just on water (polypropylene, polyethylene, polymethylpentene...), other polymers can make hollow spheres or foam. No evaporation, toxicity, environmental concerns, and so on. More choice in the colours and for the density of the lower liquid.

How big is the planned display? Shall it withstand sunlight including UV?

Consider silicone oils as a dense liquid. Dyes exist for them. They are water repellent.

Offline wildfyr

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Re: Can I somehow dye or color a liquid that is insoluble in water?
« Reply #5 on: June 19, 2018, 08:55:30 AM »
Yes, it will absolutely be an issue. Silicone is soluble in halogenated solvents. Halogenated solvents are also not advisable to work with outside a fume hood. Carbon tetrachloride is one of the worst of the bunch.

There are many many dyes which are organic soluble.

I think for your purposes it is easier to use simple oil and water, and just find a dye that is more soluble in oil than in water. Googling "oil soluble dye" gave a rich panoply of commercial products. Mineral, silicone, or even vegetable oil should be suitable (though vegetable oil will start to expire eventually).

Offline P

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Re: Can I somehow dye or color a liquid that is insoluble in water?
« Reply #6 on: June 19, 2018, 11:04:50 AM »
I think for your purposes it is easier to use simple oil and water, and just find a dye that is more soluble in oil than in water. Googling "oil soluble dye" gave a rich panoply of commercial products. Mineral, silicone, or even vegetable oil should be suitable (though vegetable oil will start to expire eventually).

I was going to suggest the same - just oil and water - you can dye them whatever colours you like then. Or just use the clear water and the yellow oil.

I think knowing what the display was going to be for might help with further suggestions.
 
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Offline OrganicDan96

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Re: Can I somehow dye or color a liquid that is insoluble in water?
« Reply #7 on: June 19, 2018, 04:30:37 PM »
i belive indigo (not indigo carmine) is not soluble in water so may work for an organic phase. how about a metal salt for an aqueous phase? you could try something like baby oil (mineral oil) for a non-toxic organic top layer and water as the dense layer

Offline GreedyBusinessMan

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Re: Can I somehow dye or color a liquid that is insoluble in water?
« Reply #8 on: June 19, 2018, 05:46:45 PM »
Thanks for the input everybody. I am still exploring the possibility of oil and water.

My main concern with that, however, is that an oil-soluble dye would TYPICALLY be water-soluble as well. From what I've found, the only dyes which aren't water-soluble are for solvents, which I don't think will work in my system (due to non-buffered sealants)

 --- I have come across something called disperse dyes, which are less soluble in water. BUT they are still soluble which will NOT work.





Offline Corribus

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Re: Can I somehow dye or color a liquid that is insoluble in water?
« Reply #9 on: June 19, 2018, 09:15:48 PM »
The Sudan dyes are extremely lipophilic. They are used mostly to stain fats, oils, and as plastic colorants.

https://en.wikipedia.org/wiki/Sudan_stain

You may also look at the range of plastic colorants available - disperse red, anthraquinone, etc. These will not dissolve appreciably in water. Certainly if you have another dye in the water phase you won't see it.

https://en.wikipedia.org/wiki/Plastic_colorant

You may also try tetraphenyl porphyrin zinc, which is dark purple.

To some extent it will greatly depend on your budget, and some dyes are more expensive than others.

The options for water soluble dyes are virtually endless.
What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?  - Richard P. Feynman

Offline Enthalpy

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Re: Can I somehow dye or color a liquid that is insoluble in water?
« Reply #10 on: June 20, 2018, 02:19:23 PM »
I expect (but didn't find the composition quickly) that dyes for silicone rubbers are insoluble in water and soluble in silicone oil. Huge choice of colours. Browse for:
silicone dye

Vegetable oils can be sensitive to air, but this depends much on their composition. Some are "siccative" and inadequate, the more saturated ones tend to last longer.

Some mineral oils are very stable over time in air, and they are light. Transformer oil is selected and processed precisely to resist oxidation. It's mainly alkanes. Or take liquid paraffin. These compounds are not considered eco-friendly, because they don't degrade quickly.

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