Beading after adhesive remover and alcohol?

[ktlimq]

In short, I wiped my hood with



3M Adhesive & Wax Remover (http://solutions.3m.com/wps/portal/3M/en_US/3MAutomotive/Aftermarket/Products/Product-Catalog/?PC_7_RJH9U5230GE3E02LECFTDQCEK3_nid=GS9BRY68DHgsR MT00NZ63RglLWPPXK82WVbl)



a few days ago,



and with



70% isopropyl alcohol the next day.



When it rained yesterday, the water beading on my hood was as good as if the hood had been waxed.



Since the last waxing in December 2008, I noticed that the beading was becoming worse recently. After wiping with 3M Adhesive & Wax Remover and alcolol, however, the beading seems to be restored.



Strange!

[imported_etml12]

Did you polish first and then use the solvent or simply strip the surface? Smoothing the surface via polishing would alter surface tension characteristics leading to beads.

[GS4_Fiend]

Alcohol absorbs moisture that`s why it beeds.

[imported_etml12]

Alcohol absorbs moisture that`s why it beeds.



Really? How? Moreover, alcohol is very volatile and will evaporate from the surface readily.

[charlesaferg]

Could quite possibly be some silicone remaining on the surface. Use more adhesive remover/paint prep. A leveled surface, even though it is smoother, still shouldn`t bead. It should have an obvious sheeting action.



This is why I believe that there is silicone from some type of LSP remaining on the surface.

[GoudyL]

Really? How? Moreover, alcohol is very volatile and will evaporate from the surface readily.



Mineral oil(s) in the Adhesive/wax remover.

[GoudyL]

Did you polish first and then use the solvent or simply strip the surface? Smoothing the surface via polishing would alter surface tension characteristics leading to beads.



Not really, since its an electrostatic interaction between the water and the paint surface. A rough surface simply has more surface area for this interaction to take place.

[David Fermani]

Brand new cars with no protection(with a cleaned surface) bead pretty good. Surface tension will affect beading and there could have been protectants in the car wash soap that was used prior too that didn`t get removed with the solvents used.

[ktlimq]

Did you polish first and then use the solvent or simply strip the surface?



I did not polish. I just used the solvent.



The car is 92 MB 300D (actually manufactured in 1991) with 306000 miles on it, and the hood has original factory paint.

I have been applying wax by hand 4~5 times a year for several years.





I wanted to apply touch up paint stick to several rock chips. Instead of spot cleaning with solvent before touch up, I cleaned the whole hood with solvent.

[imported_etml12]

This brings up some interesting "science" questions that I am just trying to get my head around. Aside from the presence of some hydrophobic film (mineral oil, wax remnants, polymers from prior products, etc.)




Not really, since its an electrostatic interaction between the water and the paint surface. A rough surface simply has more surface area for this interaction to take place.



Is this always true? Wouldn`t it depend upon the topology of the surface in question? In one case, the liquid would interface completely with the roughened surface. At the other extreme, couldn`t there exist a topology(ies) that the liquid would have difficulty penetrating the texture of the surface due to forces within the liquid and have a wetting effect?




Brand new cars with no protection(with a cleaned surface) bead pretty good. Surface tension will affect beading and there could have been protectants in the car wash soap that was used prior too that didn`t get removed with the solvents used.



My line of thinking was that a well polished surface would approach that of a new car and have the effect described by David. Any polymers/thin films people here that might be able to shed some additional light on this?

[GoudyL]

This brings up some interesting "science" questions that I am just trying to get my head around. Aside from the presence of some hydrophobic film (mineral oil, wax remnants, polymers from prior products, etc.)



[Quote]Is this always true? Wouldn`t it depend upon the topology of the surface in question? In one case, the liquid would interface completely with the roughened surface. At the other extreme, couldn`t there exist a topology(ies) that the liquid would have difficulty penetrating the texture of the surface due to forces within the liquid and have a wetting effect?



There`s two sets of interactions, Water-surface, and water-water. The water surface interaction is a function of how hydrophilic/hydrophobic the surface is, what the waters surface tension is, and how much surface area there is to contact.



Depending on the ratio of the water surface vs water-water interactions, the water will either prefer to interact with itself (forming a bead) or interact with the surface (forming a sheet)



Waxes/polishes/oils tend to form a very smooth "level" surface which is also hydrophobic, and does not carry an electric charge. So that greatly reduces the amount of surface area for the water to interact with.




Any polymers/thin films people here that might be able to shed some additional light on this?



New cars are usually preped by the dealer and there are various agents in the paint which make it hydrophobic at first.

[David Fermani]

New cars are usually preped by the dealer and there are various agents in the paint which make it hydrophobic at first.



I`ve seen many new cars that aren`t yet touched by the dealer that bead water.



What agents *in* the paint are you referring to?

[GoudyL]

Leveling agents which help the paint spread better and form an even surface as it is applied. They tend to have very interesting surface chemistries.

[David Fermani]

So you`re saying that these "leveling agents" are present at 1st when an OEM finish is new, but then evaporate/fall off some how? I wasn`t aware that the chemistry of OEM finishes changed with time? Please explain more.....

[mborner]

I don`t know how it works, either, but I work in a new car dealership and brand new cars with absolutely nothing on the paint will bead like mad. I`ve also seen freshly painted cars (less than 6 hours dry) bead water like crazy.