Many DIYers wonder if they have to sand spray paint. I made some research and here is what I discovered.
You don’t have to sand spray paint unless you want to put another coat or a sealant over the spray paint coating.
Spray paints usually have a natural glossy finish that doesn’t support proper paint adhesion. So if you would be applying another coat of spray paint or a sealant over the existing spray paint, you’ll have to sand the gloss off.
You should sand spray paint lightly with a fine-grit sandpaper. Coarse and medium-grit sandpaper can ruin the spray paint completely. You should also know that wet-sanding is preferred for sanding spray paint because it guarantees smoother results.
Let’s dive in to discover more about sanding spray paints.
How Long Should Spray Paint Dry Before Sanding?
You should let the spray paint dry for a minimum of 1 hour before sanding. On average, spray paint manufacturers advise leaving at least an hour of dry time before sanding the spray paint.
You should know that the type of spray paint, number of coats, and environmental conditions all affect how long to wait before you can sand the spray paint.
Water-based spray paints generally dry faster than oil-based spray paints due to the nature of the paint thinner. As such, you’ll be able to sand water-based spray paints sooner than oil-based spray paints.
On average, you can sand a water-based spray paint coating in about 30 minutes while oil-based spray paint coating will require at least an hour or two.
The number of coats and environmental conditions also affect the time to wait before sanding. The more coats you add, the thicker the spray paint will be and the longer you have to wait before sanding. Also, if the ambient weather is cool or moist, the spray paint will take longer to dry and longer before you can sand. In hot or warm weather, the spray paint will dry faster and can be sanded quicker.
You shouldn’t sand spray paint unless it has completely dried. This is because spray paints contain a high volume of compressed air, chemicals, and oils. If you sand while these chemicals are still wet, you’ll release VOCs and paint fumes into the air.
Should You Sand Between Coats Of Spray Paint?
You should sand between coats of spray paint. While applying spray paint, sanding between coats will ensure proper paint bonding and a smooth finish that wouldn’t crack or peel off.
It’s generally advised to sand between coats of spray paint. This is because spray paints have a natural sheen or gloss in the paint formula. The gloss gives the spray paint a beautiful finish but the gloss also makes it hard for other coats of paints to stick to the existing coat.
So before you can apply the second coat of spray paint, you need to lightly sand the gloss off the first coat to allow the second coat to bite and stick properly. You should also do this before applying the third coat of spray paint.
But do you have to sand the last coat of spray paint? Let’s find out.
Do You Have To Sand The Last Coat Of Spray Paint?
You don’t have to sand the last coat of spray paint unless you want to apply a sealant or top coat over the spray paint.
While sanding between coats of spray paint is necessary, you don’t need to sand the final coat. This is because the last coat of the spray paint is meant to reveal the finish of the spray paint. Spray paints have a natural sheen that produces a glossy finish. This finish reflects light and protects the spray paint.
If you sand the final coat, the natural sheen will be removed. This means the spray paint finish will be neither glossy nor reflective. Also, there wouldn’t be any protective layer on the spray paint meaning that the finish will be exposed to moisture, dust, and scratches that will quickly damage the finish.
The only time you are allowed to sand the final coat of spray paint is if you want to put another coat over the final coat. For instance, if you want to seal the spray paint with a top coat, you need to sand the final coat of spray paint to remove the sheen and allow the sealant to bite and stick well.
You can also sand the spray paint if you want a distressed finish. A distressed finish is achieved by sanding the final coat so the finish looks old and worn out. If you’ll like that, then you can sand the final coat but ensure to only sand the final coat with a fine-grit sandpaper.
Another thing to know is if you need to sand before applying spray paint.
Do You Need To Sand Before Applying Spray Paint?
You need to sand before applying spray paint. This is to allow the spray paint to bite and stick to the surface properly.
Also, sanding before applying the spray paint helps to remove dust nibs and grain on the surface that can cause a bumpy finish. Finally, sanding before applying the spray paint helps to even out grain to ensure that the finish comes out clean and smooth.
Sanding before applying paint is necessary not just for spray paints but for every type of paint. When you sand, the abrasive side of the sandpaper removes the objects on the surface that can cause pimples and bumps in the finish. This helps to make the finish smooth and flawless.
The sandpaper also creates tiny ridges on the surface that the spray paint can bite into when applied. This helps with proper paint bonding.
To sand, you should start with medium-grit sandpaper to remove bumps and imperfections. Then finish off with fine-grit sandpaper to even grain and smoothen the surface.
So now you know what happens when you sand before applying the spray paint. But can you apply spray paint without sanding? Let’s find out.
Can You Apply Spray Paint Without Sanding?
You can but you shouldn’t apply spray paint without sanding. As explained earlier, the purpose of sanding before applying the paint is to allow the finish to come out smooth and strong.
So if you spray paint without sanding first, there will be poor paint adhesion. Not just that, the finish will not come out clean or smooth. The result for spray painting without sanding first is a rough and weak finish.
However, you can apply spray paint without sanding and still get a good finish but this is only allowed in the following cases:
When The Surface Is Perfect
When you want to spray paint an item, the surface is usually defective. But if the surface is perfect, you can apply the spray paint without sanding first. For the surface to be perfect,
- It should be smooth
- It should have no bumps, cracks, or hole
- It should be clean and free of grease or stains
If all these conditions are met, then you can apply the spray paint without sanding first. All you’ll need in this case are two coats of paint primer before you apply the spray paint.
When There Is an Existing Paint On The Surface
If you have existing paint on the surface, you don’t need to sand. This is because the existing paint will serve as a good undercoat to cover the imperfections on the surface and provide a smooth base coat for the spray paint to bite into.
All you’ll need in this case is to properly clean and degrease the existing paint to prevent bleed-through later in the spray paint finish.
However, you should know that if the existing paint was sealed, you’ll have to sand it. In this case, sanding is necessary to remove the sealant so the spray paint can stick.
When You Need a Quick Fix
If you need a quick fix on an item, you can skip the sanding process. But you should know that the spot that you fixed will not have the same smoothness or finish as the remaining areas.
Will Wet-Sanding Remove Spray Paint?
Wet-sanding will not remove spray paint if you sand correctly and leave enough dry time before sanding.
Wet-sanding is a type of sanding where you use water and waterproof sandpaper to sand the spray paint. This type of sanding removes the most dust and gives smoother results than dry-sanding. But, if you use this method before the spray paint has dried enough, you’ll end up ruining the finish and removing the spray paint.
That said, you should wait at least 24 hours (a day) before you wet-sand spray paint. This gives the spray paint enough time to cure and harden. So when you wet sand, the spray paint will not come off.
Most DIYers that claimed wet-sanding removed the spray paint, probably did sand before the spray paint was dry enough or they used the wrong type of sandpaper. The right sandpaper for wet-sanding spray paint is fine-grit waterproof sandpaper. If you use regular sandpaper or medium-grit sandpaper, you’ll remove the spray paint.
As an expert tip, it’s best to leave wet-sanding to experienced professionals. Or, do a bit of practice on another surface before trying your luck on the spray paint.
Overall, sanding and paint application go hand in hand and this is the same for spray paints. Before you apply the spray paint, ensure to sand the surface so it’s smooth and ready to absorb the paint. Also, ensure to sand between coats with fine-grit sandpaper for proper paint adhesion.
Remember not to sand the final coat unless you want to seal it or you want a distressed finish. As long as you use the right sandpaper and leave enough dry time before sanding, you’ll get the best results.