You can paint over most finishes– but can you paint over spray paint?
You can paint over spray paint, but only after sanding the surface. Also, you need to apply at least a coat of primer on the surface to block out the cellulose in the spray paint as paint doesn’t stick well to it,
To paint over an oil-based or graffiti spray finish you must apply a coat of stain-blocking oil-based primer first.
Types of Paint To Use
Any type of paint will stick over a sprayed finish, if the finish is sanded and primed. The purpose of sanding is to abrade the existing finish and remove the glossy finish, so it can accept new coats. Paints won’t stick directly to it without sanding.
The purpose of priming is to block out the cellulose (and oils) in the sprayed finish so new paints can be applied.
While any type of paint sticks to it, it’s best to use water-based acrylic over spray paint. The water-based acrylic has polyacrylates (or synthetic acrylic resins) that stick well to a sprayed finish as long as it’s primed. Plus, water-based acrylic has vibrant colors that cover the color of the existing finish well.
However, if the finish is sealed, no paint will stick over it directly. Sealants have a moisture-resistant top layer that repels liquid. You’ll need to strip off or sand the top layer of the sealant and prime it before applying a new coat over it.
Don’t use a thin or light-colored coating if you want to cover a dark spray finish. If the finish is darker than the shade of coating you put over it, the spray paint can bleed through the new coating.
To get the best results, use coatings with the same base as the spray paint underneath. So, only use water-based over a water-based finish.
Is Sanding and Priming Necessary? (Comparison Chart)
Here’s a chart that tells you if you need to prime or sand:
|Water-based spray paint||Oil-based spray paint|
|Priming||Not necessary||Necessary (Use water-based primer over it).|
|De-glossing||Not needed since it doesn't have a glossy finish.||Necessary as they have a gloss that will repel paint.|
|Water-based paint||It will stick||It will not stick without a primer|
|Oil-based paint||It will stick||It will stick better with a primer|
How To Paint Over Spray Paint?
Painting over spray paint isn’t difficult. But there are a few basic steps to carry out before the paint is applied. This guide will reveal all you need to know about painting over spray paint. First, you’ll need some tools and supplies:
- Rags or tack cloth
- Medium-grit sandpaper
- Fine-grit sandpaper
- Drop sheet
- Acrylic paint
- A sealant (optional)
- Paint stripper (only if the spray paint was sealed)
1. Cover The Work Area
Covering the work area prevents spills from splattering on the floor or walls. You have to cover everything using a large drop sheet and tape to hold the sheet down.
You should also remove nearby objects and open all windows and doors for proper ventilation. If you are using oil-based paint, it’s recommended to work outdoors.
2. Find The Type of Finish
The type of finish that is applied determines the prep steps you will take.
To know the type:
- Add a few drops of water to the existing finish.
- If the water changes color, the spray paint used is oil-based. You need to prime it.
- If the water remains clear, the finish used is water-based. You don’t need to prime the surface — just sand it lightly.
You need to check if the finish is sealed. To do this, drag your nail across the finish. If you see a build-up of color on the tip of your nail, the finish isn’t sealed. If you notice gloss or film on the tip of the nail, the finish is sealed.
3. Remove The Gloss Layer
If the finish is sealed, it will have a glossy top layer. This layer is water-resistant and prevents new paints from sticking properly. So, you need to remove the glossy layer first. To de-gloss spray paint, use sandpaper or a paint stripper.
Sandpaper doesn’t remove the entire top layer or finish, it removes just enough to allow the paint to bite (stick) into the finish. But, sanding can be tedious, especially on large surfaces. So it’s advised to use a palm sander to remove the gloss.
A paint stripper will remove the entire glossy top layer, so you have to prep the surface from the scratch
4. Scuff The Finish
Use medium-grit sandpaper to scuff the finish. This abrades the coating and creates ridges for the new paint to stick (bite) into.
To remove imperfections or bumps from the finish, use medium-grit sandpaper (150-grit). If the surface has corners, use sanding sheets. You can fold the sheets to get into corners and tight spaces.
After scuffing the finish, use fine-grit (220-grit) sandpaper to smoothen the surface. This helps to achieve a smooth finish.
5. Apply Two Coats of Primer
Apply two coats of primer over the finish. The primer creates a textured layer and allows new paints to stick over it. It’s recommended to use water-based primer since all paints can stick over it.
To apply it, use a paintbrush. Wait until the first coating dries before applying the next one.
6. Apply The New Paint
It’s advised to use acrylic paint over the spray paint. To apply it, use a sprayer, roller, or brush (for small surfaces). To get the best results, apply thin coats since they dry faster and you can control them easier. It’s advised to apply three coats.
6. Seal The Finish (Optional)
Once the final coating dries, seal the finish with a sealant. A sealant, such as polyurethane, will cover the finish and create a glossy layer that protects it from moisture, water, and other damage. This step is optional, but it helps the finish last longer, especially on outdoor surfaces.
Can You Paint Over Spray Primer?
You can only paint over water-based spray primer. Oil-based spray primer will repel any coating that is not oil-based. Water-based spray primer allows any type of paint to stick.
Most spray paint and primers are oil-based, so you can’t paint over them with a water-based finish. This is because oil-based finishes have a glossy moisture-resistant and rigid layer that prevents penetration.
If you paint over a sprayed oil-based primer with water-based paint, the finish flexibility will be affected since it can’t move over the rigid oil-based primer. This causes the finish to crack or blister.
However, if the water-based spray primer has cured, you can apply all types of paint over it.
Types of Paint You Can Apply:
You can apply latex paint over a sprayed finish only if you sand and prime the finish first. Sanding removes imperfections and the gloss layer of the finish. While priming provides a smooth surface for the latex paint to sit on.
Latex is water-based and shouldn’t be used over oil-based or sealed spray finishes without priming first. That’s because it won’t stick over an oil-based glossy finish. So, you must sand and prime to remove (or cover) the glossy layer. However, you can only apply it directly to a water-based spray finish.
You shouldn’t apply latex paint over graffiti spray paint. This is because graffiti contains synthetic oils and chemicals that repel it. The only apply it is to remove the graffiti first. You can remove using a stripping compound or alcohol-based solvent.
Latex paint is an ideal choice to use over it as it’s flexible and can withstand temperature changes by expanding in hot weather and contracting when it’s cold. This prevents damage to the surface underneath. However, you must seal it to make the finish last longer.
You can apply emulsion over it, but first, you must sand and prime the spray paint with a water-based primer.
Emulsion paint is water-based, while the sprayed finish is usually oil-based. As such, it can’t stick well to it because water doesn’t adhere well to oil. But if you sand and use a water-based primer first, the emulsion paint will stick to the water-based primer coating.
However, emulsion sticks well to water-based finishes. That’s because both finishes have an identical make-up and solvent that makes them compatible.
You can apply a new spray paint coating over an old one, but both must have the same solvent (water or oil). You shouldn’t apply water-based spray paint over oil-based spray paint because it won’t stick.
Chalk paint is water-based and has impressive bonding qualities, so it will stick over a water-based spray paint finish. However, if the finish is oil-based, it won’t stick without sanding or applying a primer first.
You can apply wood stain over spray paint, but you need to sand the finish first. Wood stain penetrates the surface and doesn’t stop at the top of the layer. So, you need to sand existing to open holes that wood stain can penetrate.
However, it’s better to remove the existing finish completely and then apply the stain.
Overall, you can apply paint over spray paint, but you have to sand and prime the coating first. Especially, if you want to use water-based paint.
Tony is a professional painter and an author of DIY Geeks. Tony has completed over 1,000 painting projects for his clients. It's safe to say he knows what he Is talking about,