Anyone who has painted a room before is familiar with primer paint. When a room needs to be painted, you head to the paint store and leave with two cans: your shade of choice and a primer.
Walls in a house are just one surface that can be painted though. Just about anything can receive a fresh coat of paint; however, primer is not one size fits all. You have to choose the correct type for your project.
So what surfaces require either a self-etching primer or a regular primer? Surfaces like wood, stone, or brick only need a regular primer. Other materials, like bare metal, aluminum, and fiberglass, should be prepared with a self-etching primer.
What is Primer?
Let’s start at the beginning. What is the purpose of primer? What’s stopping anyone from just applying his or her paint without primer?
Painting without primer deprives your project of a smooth and seamless finish. Without using an undercoat, the quality of your paint job suffers.
Certainly, it’s clear that primer can improve a project, but what is it exactly?
At its core, primer is a type of paint. It’s a paint intended as an undercoat that prepares numerous surfaces for a topcoat.
Regular primer can be an adhesion-promoting or a porosity-sealing type. Both subtypes solve the problems posed by the particular surface being painted, according to scientist Steve Smith (source).
If a primer promotes adhesion, its main purpose is to help the future topcoat adhere to the surface. For example, most paints can’t work on wet wood. Specialized undercoats, like damp concrete primers, can bond with wet wood and concrete (source).
On the other hand, some surfaces are porous, and that makes a smooth coat of paint difficult to achieve. Throwing on a layer of paint without a specific primer could lead to undesirable paint bubbles or a lot of soaked-in paint.
According to paint company Kilz, “If not properly sealed, porous surfaces like concrete, new wood and drywall (even flat paint) can soak up a lot of paint, costing you valuable time, money — and paint” (source).
Now it’s clear that a good painting project needs a primer. Still, how the primer is applied is just as important as picking the correct type.
How to Apply Regular Primer
If you haven’t primed a surface before, it’s actually a simple process. The sequence below comes from the DIY-giant The Home Depot, which specifically refers to painting walls in a home (source).
Certain steps, such as spackling imperfections, may not apply to your project. Before putting a brush to paint, check out the surface and consider what end result you are looking for.
- Caulk or spackle any imperfections
- Let dry completely
- Smooth the caulking or spackling with sandpaper
- Paint on the primer, working top to bottom
- Let dry completely
- Smooth bumps and ridges with very fine sandpaper
What is Self-Etching Primer?
Self-etching primer is also used as a primary undercoat. It’s a specialized primer intended for use on metal, aluminum, and fiberglass (source).
Self-etching primers can do something that regular primers cannot. It contains an acidic chemical that bonds, or etches, onto a metallic surface. Etching readies metal for a topcoat (source).
The etching creates a rougher surface for the topcoat to cling to, much like sanding would accomplish.
It is often still recommended by experts to sand the metal before (and after!) the primer to ensure the best adhesion to the next coat of paint. If the self-etching primer creates a rough texture, why sand? Again, you want the best foundation possible.
A primer that is self-etching is normally considered a high-build coating (HBC). HBCs are formulated to only require one coat to complete the job (source). Self-etching primer is thick and typically only needs one coat before you can move on to the topcoat.
How to Apply Self-Etching Primer
For the most part, applying a self-etching primer is like applying a regular primer. Both involve clean and smooth surfaces. Rust-oleum is a trusted name in the painting game. According to the product’s manual, below is the best method for using a self-etching primer (source).
Before starting any project, check for any damage that can be easily repaired. Self-etching primer is handy, but it can’t repair cracks in fiberglass. Rust should also be sanded off beforehand.
- Ensure surface is clean from grease and oils
- Let dry completely
- Shake can well
- Keep can 12-16” from surface
- Spray in a back-and-forth motion
- Let dry completely
- Smooth any bumps or rides with sandpaper
When to Use Regular Primer
As a general rule, organic (or organic-like) materials, like wood, only require a regular primer. “Organic” refers, of course, to natural-occurring materials.
Wood is a natural material, along with the clay that bricks are made of. Materials like this don’t need a heavy-duty etching primer. Latex- or oil-based primers will work.
Some inorganic materials also fall in the regular primer category. Drywall that surrounds us in the rooms of our homes is a contender for normal primer. Remember, porous materials like drywall soak up paint, so a porosity-sealing primer is the way to go.
Wood is probably one of the most commonly painted surfaces. Pinterest is oversaturated with DIY-project suggestions involving wood. Furniture, pallets, and home décor are only a tiny portion of the projects people do.
You might be transforming a pallet into a wine bottle shelf, or creating a unique wooden photo frame. Regardless of your desired result, you will need to apply primer to the wood.
What about the bigger projects? Maybe you’re looking into giving your clapboard house a new coat of paint (source). What will you still need? Primer!
Before starting with the primer, the previous stain, if any, will need to be removed. Habitat for Humanity recommends washing the wood with dishwashing soap (no, really!) before attempting to remove the stain. The sandpaper should remove an old stain but use a chemical stripper for stubborn nooks and crannies (source).
For wood, an oil-based primer is the best option. Latex primer does work, but an oil-based one penetrates deeper. When applying primer, ensure that it is spread out thin and evenly. Consider an additional coat if you are feeling unsure (source).
Rocks, of course, are naturally occurring minerals. Bricks, meanwhile, are basically man made rocks. Brick is a long-lasting and attractive building material.
For painting masonry (i.e. a fireplace or similar), always go with a latex primer and paint. Latex works as a filler in the open texture of the material. With bricks, it’s best to go with several thin layers of paint instead of a couple of thick messy ones (source).
No one should ever paint brand-new masonry. It is highly recommended that bricks should not be painted until a month after being laid. New bricks and mortar can trap the moisture in paint and ruin the masonry (source).
You’d be hard-pressed to find a human on this planet without some experience with painting drywall. Even if someone has never touched a paintbrush, they have at least been around someone else as they painted a room.
Primer on the walls of a home is about more than just a smooth finish. Lowes notes that primer can “block tannin, water, grease and smoke stains that can bleed through your topcoat” (source). If you aren’t convinced smoke stains are that serious, perform a Google image search of “smoke stains” – not pretty.
The type of primer needed for painting drywall can be found at any hardware store or local paint shop. According to experts at Lowe’s Home Improvement, you should opt for a latex-based paint. Oil-based paint should be reserved for wallpaper or stains (source).
You may even choose to use acrylic paint for your drywall. Acrylic is durable; it is less likely to crack when compared to oil-based paint (source). Also, it’s not flammable, making it a safer option for a topcoat.
When to Use Self-Etching Primer
Mark Golden, CEO of Golden Artists Colors, defines metals as “any elements which have metallic properties, including the ability to conduct electricity, being able to create permanent shape and form as well as deformed at average temperatures and typically have a luster” (source).
To put it simply, metal is a versatile material. It’s found in homes, cars, and watercrafts. There is an endless list of metal projects people embark on, but here’s a list of the most common ones.
If one segment of the population debates self-etching primer use more than any other, it’s the automotive enthusiasts. The average everyday car owner probably isn’t privy to the ins and outs of car-painting. No, so-called “gear heads” are a few steps above a normal car owner.
Forum after forum, you’ll find discussions on how to best care for a project or vintage car. Self-etching primer is a favorite among those in the know. It gives the finish these car owners are seeking, plus it covers up any rust.
Cars rust. It’s not something we like to think about, but it’s a fact. A strong base coat primer can help prevent the spread of rust.
Before a self-etching primer ever touches a car, the rust should be gone. This involves elbow grease, specifically, removing the rust by hand with sandpaper. It’s tedious work but worth it.
When the area is rust-free, apply your base coat, otherwise known as the self-etching primer. If necessary, apply more than one layer (source).
Wrought-iron fences are a common paint project. Thanks to the iron, this fencing can last a long time, but the paint on it might not. Homeowners may find their fence in need of a touch-up.
Iron fence owners are encouraged to check their fencing for deterioration. It is not always obvious to spot. When checking, look for discrepancies, like rust stains, oils, or uneven surfaces (source).
Iron fences can be spot-painted instead of being entirely redone. No matter the size of the intended spot, it needs to be prepared for a topcoat. A layer of self-etching primer creates a smooth surface and finish for the top layer of paint to adhere to.
Aluminum isn’t just for foil in the kitchen. It’s actually the most commonly found metal in the earth’s crust (source).
It’s lucky that it’s so prevalent. We use it in so many applications; aluminum foil is only the beginning. It is used in everything from art to patio furniture to bicycle frames.
Aluminum is a popular material in outdoor furnishings. This is an ideal choice because it makes the chairs and tables lightweight and easy to move around or even store away for a season.
Since patio furniture is exposed to the elements at all times, the paint job on it can easily take a hit. If you find your furniture needing a touch-up, you’ll also need some self-etching primer (source).
Painting aluminum patio furniture follows the same steps as most painting projects. You first need to ensure the surface is clean and dry. The surface will need to be sanded before and after the primer is applied (source).
A bicycle that has traveled hundreds of miles might have a frame that looks worse for wear. On the other hand, for the more eccentric among us, the traditional bicycles on the market just may not have enough character. There are plenty of reasons to give a bicycle frame a paint job.
The majority of bicycle frames on the market are made of aluminum. The metal keeps bicycles affordable and lightweight. Steel bicycle frames once ruled the industry but they ended up being too heavy (source).
A thin layer or two of self-etching primer makes a bicycle paint job an easy task. It includes most of the same steps of other paint jobs. Like other surfaces, make sure to clean the aluminum bicycle frame, sand it down, and then apply your primer (source).
Fiberglass is an interesting material. It is made of fine fibers, hence the name. It’s coveted for its strength (source).
Boats and Kayaks
Besides an actual entire automobile, everything mentioned in this article is relatively small in size. At the very least, they are manageable sized painting projects. However, for the more ambitious, you can always earn your sea legs.
Boats and kayaks have fiberglass exteriors. Having a professional paint your sea vehicle is always an option, but a DIY job is infinitely cheaper.
Boats (and kayaks) are made of fiberglass and have a gel coat layer on top. Every trip to the water wears away that gel coat, eventually necessitating a new coat of paint.
Is a freshly painted boat or kayak purely a vanity issue? Is a nice paint job just a way to look nice?
Actually, no, it’s not just about looking nice. Boats experience many obstacles including hitting rocks and bringing along unwanted attached animal guests. A solid paint job helps protect the boat from this (source).
As always, safety comes first. Wherever you set up your project, make sure it’s well ventilated. Paint fumes can be hazardous when inhaled.
Boats.com, an industry leader, explains the best process. Before sanding, repair any cracks. After sanding, make sure the surface is clean. Once it’s ready, apply the self-etching primer evenly (source).
Once your boat is primed and painted, do not forget a waterproof sealant!
Painting a helmet can be a fun form of self-expression. Motorcycle helmets, in particular, are typically made of fiberglass. This means that a helmet is a candidate for self-etching primer.
If you need some inspiration, one study found that wearing white or light-colored helmets significantly reduce motorcycle crash-related injury and death. If you’re easy to be seen, you have a better chance of survival (source)!
The Bicycle Helmet Safety Institute recommends checking your primer and paint carefully. Certain paints can destroy the foam in helmets, even if you’re only painting the shell. If you are unsure if your paint is compatible with your helmet, contact the manufacturer (source).
Before embarking on a painting project, you’ll need to have the right primer for the job. Primer helps make any project look professional-grade. The correct primer depends on the type of surface being painted.
Potentially porous surfaces like wood or brick need a regular primer. Drywall found in homes only needs traditional latex primer paint. Primer is a must for protecting these surfaces.
Surfaces that are more metallic and manmade will need a bit of etching. To get that chemical bonding, the surface will need to be prepared with a self-etching primer. Such a primer will help maintain the look of your car, helmet, or even bicycle.
A great-looking result requires the right primer. Before you start any painting project remember the primary necessity – primer!