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.
Water – How to get paint on rocks to last longer
paintingrepaintingwaterproofing
Related Solutions
Painting with a roller leaves an "orange peel" type texture that you can't match exactly with a brush. When you brushed your new paint on, the orange peel texture in the unsanded areas just telegraphed through your new brushed paint, but the smoothly sanded parts had no such base texture so they look visibly smoother.
To fix this I'd go over your patches again with a small roller and you should get the same sheen and texture as in the original paint.
As long as you can get it airtight, it will work just fine. I use the disposable tray liners and try to get as much of the paint off the liner as possible, pouring the remaining paint back into the can.
I leave the liner on the roller tray, cover it with plastic wrap and then put the whole thing in a tie-off garbage bag, trying to get as much of the air out as possible. Keeping it in a cool place helps to cut down evaporation too.
Another tip: 1 gallon Ziploc freezer bags are the perfect size to hold a 9" roller cover between uses:
I squeeze the roller cover out with a painter's multi-tool, drop it in the bag, and seal it up. It won't keep forever, but it will certainly last a week.
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Best Answer
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.