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If I combine a viscous oil into solution in a carrier in a ratio of between say 1:10 or 1:100 to make it low viscosity but not separate into layers.

I then place a few drops onto a larger quantity of water (think indoor water feature) to spread out as a thin film. Boiled water with a gas barrier may be less likely to start going green.

My thoughts are 100% isopropyl alcohol, 100% acetone or 95% denatured ethyl alcohol but not sure if they will cause my oil to go in to emulsion rather than float on top.

  1. Is there a carrier that will dissolve into the water but leave the very thin oil on the surface?
  2. Do I need to use a non-polar hydrocarbon that can evaporate instead of a polar solvent that would move into the water?

The carrier should be safe enough to handle and any residue non toxic to your lawn or kitchen drain when disposing of the water later and any vapours not highly flammable or toxic to inhale. It is not intended for consumption.

EDIT:
Addition to clarify for comments.

I apologize that am not able to give the specific application at this point.
The water not going green was an attempt at illustrating a possible application (I did not realise it might not even work), another similar application would be the layer of paraffin oil (iirc) that was sprayed on stagnant ponds to control mosquito larva (though mechanical sealing of their breathing tubes iirc), the sprayers were used as an aid to dispersal but I don't want a sprayer, the right carrier for me might even work for this application though no my goal.

The aim is to have some way to dispense a thin layer of oil on to the surface of still water. The final layer will be very thin and the amount of remaining oil would be less than the dispensing amount.

The oils will be of organic origin, possibly semi viscous.
The carrier is intended to get out of the way in a few minutes.
The carrier is to ease dosing and assist with spreading otherwise I could just mix it with lots of oil have thick film and large doses, not ideal.
I am indifferent of whether the carrier goes into the water or evaporates as long as it is not horrible stuff.
I will avoid noxious, toxic, explosive and greenhouse type chemicals, we are talking about drops and no likely ignition sources so flammability is not a big concern.
Part of this problem is to avoid having to require shaking, mixing or other special handling or storage of the dispensing mixture. I am worried that if I use water as a carrier with an emulsifier to prevent separation, on application the oil will not float on the surface but will disperse into the water pool.

Additional problem is that the vapour pressure cannot be so high that it needs to be held under pressure, this is the other extreme where I could just use an aerosol can with propane but that is really far from ideal.

Pentane may be in the right direction, I will look further, are there consumer applications that use pentanes?

I wonder what perfumes would do if dropped onto water, will the carrier drag oily scents into the water or let them float (note to self must run a few tests)? What are the carriers, alcohol (and read some labels)?

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    $\begingroup$ Oil is still soluble in water, so I'd guess that acetone or isopropyl alcohol could drag the oil into water and leave it there. So I'd prefer pentane or other alkane. Almost all organic solvents are flammable. The only non-toxic and non-flammable are CFC's, which should be avoided. $\endgroup$ – ssavec Sep 10 '16 at 20:42
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    $\begingroup$ What type of oil are you referring to? Mineral oil? Or vegetable oil? Also, what do you mean by "boiled water with a gas barrier may be less likely to start going green"? Air is more soluble in most any oil than it is in water.It's also unclear what your final goal is. Do you want a thin film of oil on top of water? If so, why do you need a diluent at all? Or do you want to dissolve the oil evenly and homogeneously in a water phase? $\endgroup$ – Curt F. Sep 11 '16 at 1:55
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    $\begingroup$ I have the same question as @CurtF., if the goal is to create a thin film of the oil on top of the water, why must you dilute it first in a carrier? Can't you just add it to the top of the water? $\endgroup$ – J M Sep 13 '16 at 20:31
  • $\begingroup$ @JM For ease of dispensing, I wish to have only a little of the oil remain on the water, it is slightly viscous and will not be easy to dose in small amount from a practical point or be sure to cover if one were to spray it on neat. $\endgroup$ – KalleMP Sep 15 '16 at 22:27
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    $\begingroup$ The blowing agents for polystyrene foam are frequently mixtures of pentanes and are readily available in the US, I don't know about Finland. $\endgroup$ – airhuff Feb 5 '17 at 7:07

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