Spray painting is known to give smooth and fine results when used on wood and ornaments. So, can you spray paint metal?
You can spray paint metal but the metal surface has to be properly cleaned and sanded to get rid of dust, debris, and rust on it. You will also need to apply at least a coat of paint primer on the metal before painting it to allow the paint to adhere well to the metal.
Finally, you’ll need to use spray paint designed for metal. Such spray paints are designed to last long on metal. It’s also advised to use spray paint that is moisture resistant and rust-proof on metal to prevent the finish from turning brown.
Does Metal Accept Spray Paint?
Spray paints don’t stick properly to metal — bare metal especially doesn’t accept spray paints. Though the spray paint will stay on the metal initially, the finish will quickly peel off after a few weeks.
Spray paints don’t stick well to metal for 2 main reasons:
First, bare metal surfaces are usually slick and non-porous. This means the spray paint can’t bite or penetrate the metal surface. Since the paint can’t penetrate, it doesn’t stick well to the metal.
Secondly, metal surfaces are usually riddled with grime, dirt, and rust especially if the metal is outdoors. All of these will not allow the paint to stick properly. So before the metal is spray painted, you’ll need to clean, sand, and prime the metal.
Cleaning and sanding help to remove dirt and rust. While priming helps to seal the slick metal surface so the spray paint can bite into the primer coating.
It’s advised to use a self-etching primer before spray painting metal for proper paint adhesion. The self-etching primer will corrode the metal surface making it easier for the spray paint to stick better.
Types of Spray Paint To Use on Metal
To spray paint metal, it’s generally advised to pick an oil-based enamel spray paint. Oil-based enamel spray paints are durable and water-resistant meaning that the metal surface will be protected from moisture and rust. However, oil-based enamel spray paint will take longer to dry since the paint is oil-based.
Water-based acrylic paint is a great choice too, but this paint is more ideal for indoor metal surfaces. The bright color of the acrylic paint will go well on an indoor metal surface. Spray paints specially designed for metal use such as rust-oleum spray paint and Krylon paint can be used too.
These paints are formulated to stick to metal surfaces. Krylon metal spray paint is designed with a built-in primer coating, so you don’t need a separate primer.
Rust-oleum spray paints for metal have silicone compounds in the paint coating to shield the metal from heat and UV rays. All of these are great spray paints to use on metal surfaces.
However, some spray paints shouldn’t be used on metal. For instance, it’s not advised to use wood stains on metal. This is because stain penetrates the material it is used on and since metal is non-porous, the stain can’t penetrate and can’t stick well.
Also, don’t use spray paints that have poor water and heat resistance. The best spray paints for metal usually have rust protection.
How To Spray Paint Metal?
To spray paint metal, you’ll need a few tools and supplies:
- Clean rags
- Medium and fine-grit sandpaper
- Paint scraper
- Safety gear (a pair of goggles, gloves, and face mask)
- Drop sheet
- Painter’s tape
- Paint shield
- Paint primer for metal
- Spray paint for metal
Here is a quick rundown on how to do it:
- Scrape existing paint off the metal
- Sand and clean the metal
- Prime the metal surface
- Spray the paint on the metal
Now, let’s go into detail.
1. Scrape Existing Paint Off The Metal
The first step is to prep the area– wear safety gear and cover everything near the metal. While spray painting you should avoid working in a cold temperature, high temperature, or high humidity area.
Next, remove existing paint from the metal surface. This step is optional. If there isn’t any paint on the metal, you don’t have to scrape.
It’s important to scrape the existing paint to remove any rust, paint residue, or stains on the metal. All of these can prevent proper paint adhesion.
If there is existing paint on the metal, it can cause bleed-through and discoloration because metal paints have chemicals to prevent rust. These chemicals can discolor or bleed through the spray paint.
To scrape existing paint, you can use a paint scraper, a trowel, or a metallic putty knife. Ensure to scrape the paint from the base. This also helps to remove grime and rust beneath the paint. For tough paints that refuse to come off, you can use baking soda or vinegar to dissolve and remove them.
2. Sand The Metal
After scraping the existing paint, you need to sand the metal, even if you have bare metal.
Start sanding the metal with medium-grit sandpaper, 150-grit is good enough. Ensure to sand all corners and nooks of the metal. For hard-to-reach spots, you can fold a sanding sheet to get to the tight spots.
Sanding with medium-grit sandpaper first helps to remove imperfections and rust while creating a textured surface for the paint to stick. After sanding with medium-grit sandpaper, use fine-grit sandpaper. This helps to even the metal surface so you can get a smooth result.
After sanding, ensure to clean and wipe the metal surface thoroughly. You can use baking soda to clean the metal but be careful as too much baking soda can cause discoloration on the metal.
3. Prime The Metal
Before you spray paint metal, you need at least a coat of paint primer. To prime the metal, use a paintbrush to apply a coat or two of the paint primer. Wait for each coat of primer to dry before applying another. The primer coating helps the paint to stick better to the metal.
The best type of paint primer for metal is self-etching primer. The primer will etch or corrode the metal surface lightly so the paint can stick better.
You only need one coat of self-etching primer. If you don’t want to use this primer, you can go with a water-based primer that requires 2 coats. Just ensure the primer that you pick can be used on metal and will suit the spray paint.
4. Spray Paint The Metal
Next, spray paint the metal. If you will be using spray paint in a spray can, you need to shake the can for a while before spraying it so the content can be properly mixed. If you don’t do this, then the paint that comes out will not have even consistency or color.
If you would be using any other type of paint, you might need to thin it first before you can spray. This is because the paint needs to be as thin as possible so it can be properly discharged from the spray gun.
While spraying, keep at least 8 inches between the nozzle of the sprayer and the metal surface. Also, you should spray the paint in a sweeping motion to prevent spraying thick coats.
After spraying the first coat of paint, let it dry properly on the metal. This can take between 30 minutes and 4 hours depending on the type of spray paint.
When the first coat is dry, you can apply the second coat. You need 2-4 coats of spray paint on metal. When both coats have dried, you have successfully spray-painted metal.
How To Avoid Blisters When Spray Painting Metal?
Blisters will show while and after spray painting metal if you don’t prep the paint and the metal correctly. Let’s check out a few tips on how to prevent them:
1. Don’t Over-shake The Spray Paint
It’s advised to shake the spray can before spraying the paint to mix the content. But you shouldn’t over-shake the spray can. If you do, you’ll create bubbles inside the spray paint.
When you spray the paint, the bubbles will create blisters in the paint coating — so it’s best to avoid it. To prevent this, ensure to shake the paint lightly and for not more than 60 seconds.
2. Clean The Metal
If there are debris and dust on the metal, you will notice blisters forming as the paint starts to dry. To prevent blisters, ensure to properly clean and wipe the metal.
3. Remove Rust
If there is rust on the metal, blisters are guaranteed to form as the paint starts to dry. You should remove the rust by scraping and sanding the metal before the paint is sprayed on. You can also use a rust-removal chemical if the rust is heavy and much on the metal.
4. Allow Enough Dry Time Between Coats
On metal, you’ll need 2-4 coats of spray paint. Ensure that each coat dries fully before re-coating. If you re-coat too soon, the finish can develop blisters as moisture will be trapped in the coat underneath. Check the container of the spray paint for how long to wait before re-coat.
How to Keep Spray Paint from Chipping off Metal?
Spray paint will not chip off metal unless the spray paint was applied incorrectly. Spray paint will only chip off metal if:
1. Prep The Metal
If you don’t clean the metal it will be filthy, and the filth will prevent good paint adhesion. Since the spray paint adhesion is weak, the paint will not stick well and moisture, heat, and dust can easily affect the paint causing it to chip off.
2. Use The Right Type of Spray Paint
Not every type of spray paint can be used on metal. If you use spray paint that has no moisture or rust resistance, the paint will be quickly affected by moisture and it can peel and chip off.
3. Allow Enough Time Between Coats
If you re-coat too soon, the paint will not be hard when dry. This will make it easier for the paint to chip off.
4. Avoid Applying Thick Coats
If the spray paint is too thick, it can develop hairline cracks that will cause it to peel and chip off gradually.
5. Avoid Drying The Paint Too Quickly
If the spray paint dries too quickly, then the paint will not be hard. Instead, it will be flaky and can easily peel and chip off the metal.
The bottom line is as long as you use the correct spray paint and prep the metal properly, the spray paint will not chip off.
Spraying Over Painted Metal?
You shouldn’t spray paint over painted metal. This is because paints used on metal are usually oil-based and spray paint will not stick to oil-based paints. So if you spray over metal that was painted with oil-based paint, the paint will not stick properly.
Also, paints used over metal usually have additives that can repel paint. Your best bet to spray paint over a painted metal is to remove the existing paint first or at least, sand it. If you sand the existing paint, the bulk of the paint will be removed and the spray paint when applied will stick well.
Spray Paint Lasts A Lot
Spray paints last between 3 and 10 years on metal. On average, spray paint will last 5 years before you notice any imperfections or changes in the paint. The reason spray paints last a while on metal surfaces is that spray paints designed for metal are usually oil-based. As such, the spray paint will be more durable.
Spray paints designed for the metal have additives that prevent moisture from damaging the metal. These additives also make the spray paint last longer.
For instance, rust-oleum spray paints usually have silicone compounds to make the spray paint more resistant to heat. This means the paint will not be easily damaged by heat or UV rays. The additives and oil-based nature of most metal spray paints make them last longer.
How Many Coats of Spray Paint on Metal?
You need 2-4 coats of spray paint on metal. Allow each coat to dry properly before you add the next one. You shouldn’t apply more than 4 coats as the spray paint can turn sticky. You shouldn’t add less than coats on metal as the paint will start to chip off.
Overall, you can spray paint metal. You just need to prep the metal properly by cleaning, sanding, and priming it before the paint is applied.
This will make the paint stick well and come out fine. You should only use spray paints designed for metal — other types of spray paints will not stick well and will chip off quickly.