You don’t need to sand between coats of spray paint if the coating is smooth and clean. But, if the coating was applied more than 24 hours ago and is riddled with dust (or dirt), you must sand it.
To sand between coats, use fine-grit sandpaper only. Medium or coarse-grit sandpaper will remove the finish instead of smoothing it.
You don’t need to sand the final coating of spray paint as it will remove the glossy layer and expose the surface to elements.
How Long Must Spray Paint Dry Before Sanding?
Spray paint must dry for 1-4 hours before sanding. This gives the coating enough time to harden and dry to withstand the sandpaper pressure.
The exact dry time depends on the spray paint type, thickness of the coat, room temperature, and humidity levels.
You can sand water-based spray paint faster as their solvent (water) evaporates fast so the coating gets harder faster.
You will ruin (damage) the finish if you sand it too soon. A wet spray paint coating that hasn’t properly bonded to the surface will get removed if you swipe a sandpaper over it. The sandpaper will also get clogged over a wet coating.
To know if the coating is dry enough for sanding, swipe fine-grit sandpaper over it without applying pressure. If the sandpaper gets clogged, the coating is still wet and not ready for sanding. On the other hand, if the sandpaper goes smoothly over the surface, the coating is dry and strong enough to withstand sanding.
Do You Need To Sand Between Spray Paint Coats?
You don’t need to sand between water-based spray paint coats as it is applied at a high speed and has impressive bonding qualities. It will penetrate the surface deeply and stick to form a smooth coating.
You must sand between coats only if the previous coating was applied more than 24 hours ago, if the coating is riddled with dust or filth that prevent a good adhesion, or if the surface is riddled with bumps or imperfections.
You must sand between oil-based spray paint coatings as they form a glossy layer that will prevent the new coating from sticking. So, you must lightly sand to remove the gloss from the finish.
Do You Need To Sand The Final Spray Paint Coat?
You don’t need to sand the final spray paint coating as you will remove the glossy and protective layer and expose the surface underneath to different elements.
You must sand a spray paint coating only if you are planning to apply another coating over it or if you want a distressed finish. For instance, if you want to apply a sealer over the finish, sanding is recommended as it will remove imperfections.
A distressed finish is achieved by sanding the final coat so the finish looks old and worn out. However, ensure to only sand the final coat with fine-grit sandpaper.
Do You Need To Sand Before Applying Spray Paint?
You need to sand before applying spray paint to remove imperfections and bumps from the surface that can prevent good adhesion. Sanding will also remove dust nibs and grain that cause a bumpy finish.
The abrasive side of the sandpaper will remove the imperfections and bumpy layers off the surface, leaving a smooth and even (flat) surface behind. Sanding will also create tiny ridges (holes) on the surface so the paint can penetrate into them and stick better.
However, you must sand before applying spray paint if the surface is already painted (or sealed) with another finish (especially oil-based). You must remove the existing finish or at least remove its glossy layer before applying spray paint, or it won’t stick.
To sand the surface, use medium-grit sandpaper to remove bumps and imperfections. Then, finish with fine-grit sandpaper to smooth the surface.
You don’t need to sand the surface before spray paint if the following things happen.
- If the surface has no bumps, cracks, or holes and is smooth.
- If you apply paint primer before painting.
- Don’t sand over a clean surface.
- If you need a quick fix.
Does Wet-Sanding Remove Spray Paint?
Wet-sanding doesn’t remove fully dried (cured) spray paint, but it can remove semi-wet coatings.
A fully dried (cured) coating is bonded to the surface, its solvent has evaporated, and is durable enough to withstand water and sandpaper without getting removed.
Wet-sanding refers to the process of sanding a surface by using water and waterproof sandpaper to prevent dust and create a smoother surface.
If the coating hasn’t fully dried yet, wet-sanding will remove it as it will add more solvent (water) to the coating and prevent it from drying.
It’s recommended to wait 12-72 hours for the spray paint to fully dry (cure) before wet-sanding it. This gives the coating enough time to harden to withstand water without getting removed.