If you have some unused wall paint lying around, the last thing you’ll want to do is add to the collection unnecessarily by purchasing more paint. So is wall paint suitable for use on metal?
You can’t use wall paint on metal as it doesn’t adhere properly. Metal is prone to oxidation (rust) and weathering, so it’s essential to use a specially formulated paint that’s specifically labeled for use on metal surfaces. For best results, use oil-based or water-based metal paint in conjunction with metal primer.
In this article, I’ll cover:
- The pros and cons of oil- vs water-based paint
- Why you must use primer
- How to ensure a long-lasting finish when painting metal
What Kind of Paint Sticks to Metal?
There are many benefits of using water-based paint over oil-based paint on metal. But you may want to balance the cost of certain paints against the object you are painting, how it is used, and the exposure to the elements.
Here are the main things to consider:
Key Points of Oil-Based Paint
- Hides Imperfections
- Thick Coverage
- Vivid Colors
- Quick Fading
- Drying Time
Key Points of Water-Based Paint
- Easy to Clean Spills
- Drying Time
- Low Fumes
- Preparation Time
- Rusts Mild-Steel and Cast-Iron
- Easy to Damage
- Will Not Fill Dents
Primers will prepare the metal surface, increase the longevity of the paint, and leave more choices open for the types of paint you can use. An oil-based primer is better for metalwork and the paint that you want to use.
What Is the Most Durable Paint for Metal?
Oil-based paints are preferable to water-based metal paints as they are more common and longer-lasting. Oil-based paint will flex, bend, and cope better with rough treatment than water-based metal paint.
Best Metal Paint to Prevent Rust
Water-based paints will struggle to cling to most metals and will even rust untreated mild steel. This is more of a problem with welds and joints, and this rust will float to the surface and mix in with the paint as it dries.
If you do use water-based paint on steel, start by protecting the metal with a metal primer. A metal primer is also necessary for painting aluminum since its surface oxidizes within minutes of cutting it. You will not have this problem if you use oil-based paint.
Best Paint for Metal Gates
A metal gate is open to the elements, which includes storms, UV and heat from the sun, and abuse. There are many sprays available, but for the best coverage and longevity, you should use a primer then a roll-on enamel paint.
If you are trying to reduce the workload and want something fast, try the spray version of the same product.
Best Paint for Metal Crafts
Diecast toys and other crafts need a more delicate form of paint. Models and artistic projects need stronger pigments and thicker paints to prevent the colors from blending. For artistic touches to a garden gate and fine work on metal crafts, you can use a quick-drying paint pen.
Oil-based pens are easy to use, they come in a range of colors, and they work on all metal surfaces.
Do I Need to Use a Primer When Painting Metal?
You will find that spray cans for metals include the primer, or they may state that they do not need a primer. Mild steel tends to be galvanized with a zinc coating or sprayed with brown primer or oil to prevent rust.
But if you are dealing with bare mild steel without a coating, you will need to get a primer on it before it rusts. The color of the primer does not matter since you will be using paint later. The primer will help fill in imperfections in the metal and provide a tacky surface for the paint of your choice to bond to.
How to Paint Metal
There are several stages to follow when painting metal so that it looks good, makes the least mess, and lasts the longest.
Preparing the Metal Surface
- Scrape – For the best finish, you want to start with a bare surface that is free from old paint and residues. Use a scraper and sandpaper to remove loose paint and to level out the surface.
- Rust – You want to remove all loose rust and dig out any chunks that have eaten through the metal. Use a wire brush for corners and crevices. After brushing, it is worth painting on a rust reformer, which will stop rust propagation and give you a better surface for paint.
- Repair – Fill any large holes with metal filler, as this will smooth out the surface and remove entry points for rainwater. Sand flat after the filler dries.
- Short Cuts – Do not worry about small holes, as these should fill in with primer and paint. An electric sander will make the most dust, but it will make a huge difference to the speed of sanding.
- Clean – Wipe the surface down with a dry cloth to remove dust from sanding and leftover paint flakes.
- Prime – Some paints may include primer, but the best result comes with using a metal primer before using oil-based paints.
- Mineral Spirits
- Rust Reformer
- Wire Brush
- 220-Grit Sandpaper
- Metal Filler
- Metal Primer
- X” and 2″ Paintbrush (for oil-based paints)
- Oil-Based Paint (of your choosing)
- Clean Rag
- Protective Sheeting
- Painter’s Tape
Step by Step Guide
Follow the above steps for preparing and cleaning a metal surface before continuing.
Using a Spray Can
- Shake – Inside a spray can are two loose marbles for stirring up the paint. Shake the can and swirl it around for 30 seconds before trying to use it. The marbles will mix the pigment back into the thinner and give you better consistency when you begin spraying.
- Spray – Hold the nozzle of the can 6 to 12-inches from the surface that you want to spray and try to keep it this distance while you are spraying.
- Motion – Keep moving as you spray. Avoid too much paint overlap as this will lead to drips and puddles.
- Layer – Outdoor objects such as cast-iron furniture will need at least two coats. Wait an hour for each coat to dry before trying to apply another layer.
Using a Paintbrush
- Mix – Your chosen paint will have instructions on the amount and type of thinner to use. Oil-based paint will need between 5% and 10% mineral spirits – the thinner, the smoother the coat. Pour the paint into a clean container, then measure in the thinner, and mix with a clean mixing stick.
- Protection – This can be messy, so do the mixing outside and on a protective plastic sheet. You may need to pour the paint from the can back to the mixing pot and back several times for thorough mixing.
- Brush – Oil-based paints will dissolve some types of bristles, so use natural animal hair or nylon brushes to apply the paint. You can use a roller for large flat surfaces, but you may find that the roller sucks the thinner out of the paint unless you prime it with paint first.
- Dry – Brush paints take longer to dry and even out, and oil-based metal paints can take between 30 to 50 hours to dry. Once the paint dries to tacky, you can add a second coat. A single coat should be sufficient if you used a primer and a low concentration of thinner.