I worked for a short while at a paper pulp mill as a metal construction painter when I was younger. They were expanding the factory, so a lot of metal construction was built, which needed to be partly painted.
The different parts of the metal construction were prepainted but they were welded together in place, leaving the joints bare metal.
We used abrasive tools to remove damaged paint and metal residue from the welding, we then applied mineral spirits with a brush and dried it off with a dry clean cloth before applying epoxy primer on the bare metal surface. It was then painted with two coatings of 2 component polyurethane paint.
Clean the metal surface with a degreaser or mineral spirits
Maybe you’re painting a metal door or a metal chair that’s been sitting in the garage for a while and you notice that there’s a lot of oil on it. Or maybe you’re about to start a project and you want to make sure that the metal surface is clean so the paint will stick properly.
In either case, it’s helpful to know how to remove the oil before painting and there are different steps and methods for doing this depending on the object.
One of the most important steps before painting metal is to clean the surface with a degreaser or mineral spirits. This will remove any oil or grease that may be on the metal and help ensure that the paint will adhere properly.
If there’s a lot of build-up on the surface, you may need to use an abrasive cleaner to get rid of it.
Degreasers
Degreasers are used to remove grease, oil, and other contaminants from a variety of surfaces. They’re often powerful solvents that are intended to be used in small amounts or diluted before being applied to a surface. Some degreasers are designed specifically for use on metal.
KBS Klean is a concentrated, water-based, biodegradable formula that is an excellent alternative to flammable solvents and hazardous chemicals for preparing your metal with a clean surface.
It’s a powerful cleaner that deeply penetrates and removes stubborn soil from most surfaces without leaving harmful residues or emitting noxious fumes.
KBS Klean is perfect for the home or garage to effectively remove dirt, grime, oils, lubricants, grease, waxes, and other contaminants.
Acetone
Acetone is a common and very effective degreaser used for cleaning objects before painting. It evaporates quickly which means that you can prime it almost immediately.
But it’s also fairly toxic, so be sure to use it in a well-ventilated area or wear protective gear when applying it. You should also take care not to let it come into contact with skin and wash your hands thoroughly after use.
Mineral spirits
Mineral spirits are a type of solvent often used in paint thinners, they may also be referred to as paint thinner or white spirit.
Like degreasers, they’re often used as a means of removing oil or grease from surfaces. But many people choose to use mineral spirits instead of a degreaser because they believe that mineral spirits won’t leave any residue.
Mineral spirits evaporate quickly and are not healthy to inhale so be sure to use them in a well-ventilated area or use a respirator if the product will be used indoors.
Make sure to wear protective gloves and glasses for safety. Also, keep in mind that mineral spirits and acetone are highly flammable, so keep them away from any source of heat or flame.
Used rags should be allowed to dry before they’re thrown in the trash since they can self-ignite. Be sure to have a fire extinguisher nearby as well!
While working at the paper pulp mill I was one day on a scaffolding applying mineral spirits which splattered on the wooden planks I was standing on. Beside me was a welder using a grinder which created sparks that were flying all over.
The sparks ignited the mineral spirits and it went up in flames. I managed to get everything under control by jumping up and down on the flames, as a real professional does!
I kept on working but kept an extra eye on the welder from then on!
Paint thinner or mineral spirits can be found at your local hardware store and are also widely available online. Click here to check out a wide selection of mineral spirits on Amazon if you need some.
Use an abrasive cleaner if needed
Abrasive cleaners are used to remove rust, limescale, and other built-up deposits from metal surfaces. They generally contain a fine grit that can be rubbed onto the metal surface to gently grind away layers of dirt and grime. All you need to do is rub the abrasive cleaner over the affected area and then brush/wipe it off before you clean with acetone or mineral spirits.
Different kinds of abrasive cleaners:
Steel wool
Steel wool is made up of strands of very fine steel metal. It has a variety of uses, including removing rust and other mineral deposits from items like glass or chrome surfaces.
Wire brush
A wire brush is designed to clean away loose particles of dirt or rust from surfaces. It can be attached to a drill, making it easy to use to remove stubborn debris without too much elbow grease.
Emery cloth
Emery cloth is very similar to sandpaper. It usually consists of several layers of cloth that have been coated in abrasive material like emery powder, which has a rough texture.
Sandpaper
Sandpaper can be used to remove rust or other built-up mineral deposits from metal. It comes in a variety of grits, ranging from coarse to fine. The more coarse the sandpaper, the larger and more jagged the particles on its surface.
Abrasive pads
Abrasive pads are similar to sandpaper, but instead of being in a sheet or roll, they’re attached to a soft or medium foam pad. They generally come in different grits as well.
Final thoughts
Removing oil from metal before painting is an important step in order to ensure that the paint or sealant will have good adhesion.
In this quick guide, I’ve outlined different methods for removing oil from metal. Remove built-up grease or dirt with abrasive tools, apply degreaser or mineral spirits and then wipe it off with a dry cloth. Simple as that!
KBS Coatings have a 3 step rust prevention system. They have paint and cleaning products as well as How-Tos to help you further.
I hope it helped!