Self Etching Primer vs Regular Primer (Differences Explained)

There are two main types of primer; self-etching and regular primer. What’s the difference between both types of primer?

Regular primer is a paint or undercoat with no special additives or chemicals. Regular primer is traditionally a white, grey, or dark paint designed to improve paint adhesion, bonding, and smoothness. Regular primer is primarily used on wood, plaster, and masonry.

Self Etching primer on the other hand has chemicals included in its formula. These chemicals have a high acidic presence that helps the primer coating etch or corrode the material. The etching helps to produce a textured surface for the paint or top coat to sit on.

Self-etching primers are designed for slick surfaces like metal, fiberglass, and aluminum. Ordinarily, the paint will not stick to these surfaces properly. So, the self-etching primer will abrade the material slightly to allow paint to adhere properly

What is Regular Primer and What Is It Used For?

What is Regular Primer and What Is It Used For

Regular primer is a type of paint that is desired with adhesive compounds and binders. The primer is used as an undercoat before laying the paint or topcoat. Regular primer when dry produces an even and slightly textured finish. This textured finish allows the paint or topcoat to bite into the primer coating. The even nature of the finish makes the topcoat appear smooth and even when dry.

Regular primer is usually white or grey. However, there are now other colors available. The broad range of colors is made possible because the regular primer is common on surfaces that require decor and detail work. Surfaces like wood, plaster, and masonry all require a regular primer and sometimes, a brighter or deeper shade of color that can be produced by a tinted regular primer.

Most regular primers are gotten from synthetic resins, solvent (usually water), and additives. The simple chemical make-up of regular primer makes it ideal for most surfaces. The simple make-up also makes regular primer a suitable undercoat for any type of paint without repelling the paint coating.

Regular primer comes in both water-based and oil-based versions. The water-based version is used for water-based paints including latex, acrylic, and chalk. Oil-based regular primer is ideal for oil-based paints. However, regular primers have one flaw. The primer coating doesn’t work well on slick and metal surfaces. 

What is Self-Etching Primer And What Is It Used For?

What Is Self-Etching Primer And What Is It Used For

Self-etching primer is a primer coating that etches or corrodes the surface to allow the topcoat to stick properly. Self-etching primer is designed for slick materials including metal, aluminum, fiberglass, and steel.

Regular primers and paints usually have a hard time sticking to these materials since the surface is non-porous and smooth. This was why self-etching primers were designed. The primer when applied corrodes the material to produce a textured surface that the paint can bite into.

Self-etching primers usually come in a spray can which is an irony since the primer coating is usually thick. The best part of self-etching primers is that you only need one coat of layer of the primer.

Self-etching primer is also used for automotive paints and metal paints like rust-oleum paint. However, the self-etching primer has a flaw. The application of the primer and the topcoat over it is a bit complex.

So how good is self-etching primer when compared to regular primer? Let’s find out.

Regular Primer vs Self-Etching Primer: Head To Head

To compare both types of primers, we’ll use the formula of the primer and the features of the finish. Let’s get started.

The Primer’s Formula

Regular primer is gotten from a combination of solvent, binders, and synthetic resins. The paint make-up of regular primer is very simple. The primer doesn’t have any special chemicals or acids in its formula. The key ingredient is the binder in the paint coating. This is what gives it adhesion and good binding.

Self-etching primer on the other hand has a more complex formula. For starters, the primer coating is designed with chemicals and acids. The key ingredient in self-etching primer is a phosphoric acid ester. The acid is responsible for etching materials to allow the topcoat to stick.

The Dry Time

Regular primer dries faster than the self-etching primer. Regular primer takes between 30 minutes and 2 hours to dry. On average, regular water-based primers designed for water-based paints will dry enough for top coat in less than an hour. Oil-based primers will take 90 minute to dry.

Self-etching primer takes longer. Self-etching primer takes between 3 and 5 hours to dry. On average, a self-etching primer will be dry enough for a top coat in 4 hours. The reason for this long dry time is the complexity of the primer’s formula. This means you’ll spend more time on paint application if you work with a self-etching primer.

The Cost

Regular primer costs more than self-etching primer per unit. On average, a gallon of regular primer will cost you about $20 while a 16-ounce spray can of self-etching primer costs about $7. However, regular primers come in paint cans which means you get more than the quantity inside the spray can of a self-etching primer.

So for instance, if you were to cover a 225-square foot surface, a gallon of regular primer at $22 will be enough while for the self-etching primer, you’ll need about 8 16-ounce spray cans at $7 each.

That totals $56 which is more than twice the cost of the regular primer. So while regular primers cost more per unit, you’ll most likely spend more on getting enough self-etching primer.

The Type Of Surface To Be Used On

Regular primers are ideal for organic-like materials like wood and brick. You can also use regular primer on masonry, concrete, plaster, drywall, and the likes.

Self-etching primer is ideal for metal surfaces. You can’t use self-etching primer on organic material like wood because the self-etching primer is designed to etch or corrode material and wood doesn’t need corrosion.

Regular primer can also be used on metal. Though regular primers won’t work great on metal and aluminum, the primer coating will still produce a result that will be smooth and durable for a while. Self-etching primer on the other hand can only be used on metal.

The Ideal Type of Paint

Regular primers are universal and can work with virtually any type of paint. Water-based, oil-based, and metal paints can all be used on regular primers though the level of smoothness may vary.

Self-etching primers can only be used for automotive paints and metal paints. Only paints designed for use on metal, cars, steel, and aluminum can be used on self-etching primers. This gives you a limited range of choices with a self-etching primer.

Primer Application

Self-etching primers are easier to apply than regular primers. This is because self-etching primers come in a spray can so it’s easier to spray on the metal surface. You need just one coat of self-etching primer to prepare the surface.

Regular primers come in a paint can so you’ll need a paintbrush to apply the primer coating which will take more time and can reveal brush marks. You can also use a spray gun but this will require a few minutes of prep work.

Regular primers also require at least 2 coats for proper surface preparation. So paint application is easier with self-etching primer. However, that’s where the easy part ends with a self-etching primer.

After spraying the primer, the hard work begins. You’ll need to dry or wet-sand self-etching primer before painting over it. In some cases, you’ll still need an addiction coat of epoxy primer on the self-etching primer too.

So while primer application is easier with self-etching primer, painting over the primer coating is usually another round of work. For regular primer however, you don’t need another coat of primer or sandpaper before painting over it.

Rust Prevention

Regular primers can’t prevent rust unless sealed with a rust-resistant sealant or top coat. Self-etching primer can prevent rust on metal surfaces. This is because self-etching primer binds with the Metal to produce a moisture-resistant coating.

Sealing

Regular primer is a better sealant than a self-etching primer. Regular primers, especially shellac primers, are designed to seal and block stains, moisture, and oils from bleeding through the primer coating and paint when applied.

Self-etching primer is not a great sealant. Self-etching primer is more tuned to stop moisture from penetrating the primer coating to the metal underneath. It’s not ideal for sealing stains and moisture but it’s great for protecting the material underneath from spills.

In simple words, regular primer prevents moisture and oils from coming up from the surface. Self-etching primer prevents moisture and oils from penetrating or going down to the material underneath.

When Should You Use Regular Primer?

You should use regular primer when you want to paint over an organic material like wood or clay (brick). You should also use regular primer when you want to paint over drywall, concrete, masonry, plastic, and the likes. Usually, any surface material except metal and fiberglass should be coated with regular primer before painting.

If you are working on a defective surface or if the surface is riddled with dirt, grease, or oils, you should use a stain-blocking regular primer like shellac to seal the surface.

Also, when you are working with any type of paint apart from automotive or metal paints, you should use a regular primer. However, always ensure to pick the right type of primer for the task. Use regular latex primer for water-based paints and oil-based primer for oil-based paints and sealants.

Related Read: Water Based Primer vs Oil Based Primer?

When Should You Use Self-Etching Primer?

You should use self-etching primer when you want to paint over a metal surface. Metal surfaces including aluminum, steel, and even fiberglass should all be coated with self-etching primer before being painted over.

You should also use self-etching primer when working with automotive paint. Paints designed for metal, cars, and steel all require a coat of self-etching primer. To prevent rust, you should also use self-etching primer.

FAQ’s

Do You Need To Sand Before Applying Self-Etching Primer?

You don’t need to sand before applying self-etching primer. You only need to clean the metal before applying the primer. However, you may need to sand the self-etching primer before you apply paint over it. Some self-etching primers require sanding before you paint over, and some don’t. Always check the manufacturer’s instructions for this. 

Can You Paint Over Self-Etching Primer?

You can paint over self-etching primer but you need to sand it first. You also may need to apply another coat of regular primer over self-etching primer for the paint to stick better. Before applying paint over self-etching primer, the primer should dry completely. 

Final Words

Overall, regular primer and self-etching primer are both great choices. But you should only use self-etching primer for metal while regular primer can be used for any other surface.

Adequate preparation is key before using any of these primers for your painting task. Also, ensure to always go for the right type of primer to prevent painting mistakes.

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