Re: Subject: Scientific Investigation of Repeated Curling and Uncurling of Dry

Hello, mhamed...

Your question is a long one, and we'll go through it bit by bit.

Mhamed: Subject: Scientific Investigation of Repeated Curling and Uncurling of Dry Black 
Paint Exposed to Gasoline. A very thin, square-shaped piece of dry black paint, believed 
to be intended for painting iron, is placed on a solid surface. When a small amount of 
gasoline is present on the surface, the edges of the paint repeatedly curl inward and then 
unfold again. The piece remains in contact with the solid surface throughout the process.

        MadScientist. This does not meet the standards for a scientific investigation. Did you,
for example, actually measure the thickness of the paint? Moreover, the language employed
does not suggest you know the provenance of the paint involved. Is it an oil-based paint? A
marine paint? A water-based paint? Where/when was it manufactured?  In addition, gasoline
is not a precise term, since all gasolines are a mixture of many molecules. Most of it will
consist of medium-length alkanes, but it is not at all unusual for the manufacturers of the 
gasoline to vary the contents depending on the local weather conditions (e.g. adding more
lightweight volatiles in cold areas).  You need to get a better knowledge of both the substrate
(paint) and solvent (gasoline) before proceeding further.

Mhamed: I have also observed movement when the material is exposed to gasoline vapor, 
without direct contact with the liquid.

        Mad Scientist: 'observed movement' is vague. Did it curl? Did it swell? Bubble up?

Mhamed: 1. Could this phenomenon be caused by changes in surface tension, solvent 
absorption, or mechanical stresses within the paint?

        MadScientist: Most likely this is due to volume changes in your black paint substrate
as it absorbs some constituents of the gasoline, from either the vapor (which will have 
more of the lighter alkanes in it than the bulk gasoline) or the liquid. You did not mention 
any time-related observations, which would be of interest. How long did it take to observe 
the same amount of curling in both cases (exposed to vapor, exposed to  liquid)? How 
long to uncurl? Was it temperature dependent?

Mhamed: 2. Could electrostatic forces play a role, given that gasoline molecules are 
electrically neutral overall?

     MadScientist: unlikely

Mhamed: 3. Are there any previously published scientific studies documenting a similar 
phenomenon?

       MadScientist: There is a vast literature on adsorption of hydrocarbons into all sorts of
substrates. As to specifics for paints, you are best advised to consult paint manufacturers 
for data on their products that match the kind of paint you are investigating. You should also 
consult manufacturers of paint removers, many of which use aliphatic compounds (plus
 aromatic --i.e. containing ring molecules -- compounds) similar to those in gasoline.

Mhamed: 4. What scientific methods could be used to identify the mechanism safely and 
determine whether this observation has any research novelty?

       MadScientist: Standard methods to identify organic compounds (e.g. infrared spectroscopy, gas 
chromatography) should be considered first. Safely doing so will require fume hoods and appropriate
fire extinguishing gear; the gasoline and its components are all highly flammable.  In addition, the dried
paint may be investigated by such methods as secondary ion mass spectroscopy to see if there are 
constituents (e.g. titanium dioxide is often added to white paints) in it that are not organic in nature.

Mhamed: I do not yet know the exact chemical composition of the paint, and I do not want 
to assume a mechanism without scientific evidence.

      MadScientist: First order of business, then is to get the identity and composition of this particular
paint.