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Occasionally I paint a rock outside and would like it to be unaffected by weather as well as needing to be repainted for a while. I was looking into hydrophobic spray - and was wondering if anyone could confirm it would work for my needs or suggest anything else.

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    @DanielGriscom my goal is to not be able to paint over it – Jordan.J.D Mar 9 '16 at 17:39
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    You want it to resist paint? Are you trying to prevent vandalism or to prevent yourself from painting it again? – TFK Mar 9 '16 at 18:41
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    @TFK well, vandalism but i dont need to paint it again either once it is painted the first time. thank you for the reply. – Jordan.J.D Mar 9 '16 at 18:41
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    I'm not certain that there is a paint out there than can completely prevent being painted on. You can look up vandal-resident/graffiti-resistent paints and coatings. Typically, more or less I assume, graffiti has to be dealt with after the dead has been done. – TFK Mar 9 '16 at 18:46
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    Oil is the bane of paint application. Try Vaseline. – Mazura Mar 9 '16 at 23:34
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Strength of paint bonding depends on the surface. A surface with lots of microscopic roughness, like something worked over with 400 grit sandpaper, is going to bond well. Something microscopically smooth, like a sheet of glass, will bond poorly. But even on a poor bond, the paint will want to stay there just for lack of physical motiviation to go somewhere else.

Weather is not enough to provide that motivation. It needs help, with a stripper that is compatible with the protective layer, and/or scrub brushes and elbow grease. This is a hard problem, and transit agencies with rail operations are at the leading edge of the field. (Building managers less so, since they can repaint.) They use rather exotic paints you will not find at Lowes. This may be a lot of work.

Hydrophobic films can only work against water based paints. Common graffiti paint in spray-cans is oil based. In any case, hydrophobic coatings are not magic, they can't make the applied paint levitate and move downrange. The paint will still sit on the protected item, will just hopefully be easier to remove.

  • to elaborate on the hydrophobic coating, on a large spherical rock, would the paint not bead up and fall? - also do you have a suggestion for a high quality hydrophobic spray / coating – Jordan.J.D Mar 11 '16 at 19:11
  • Not really, it's a tough and specialized field and I don't do anything in it. I notice one of their weapons is 2-part polyurethane coatings, which I love, but they are hard to source and expensive. It still requires scrubbing the stuff off with solvent, so, still lots of manual labor. – Harper - Reinstate Monica Mar 11 '16 at 22:38
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Nothing will stop the need for refreshing. But, a UV resistant trash bag, tarp or poly sheeting would last the longest. Wrap the rock tight & tie-it or tape it & you're done. Replace or re-wrap in the future to refresh it. No paint, no brushes, no peeling, no problem.

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