What Is Paint Primer? (Everything You Need To Know)

There are several types of paints out there such as regular paints, sealants, stain-blockers, and the likes. Today, we are going to look at a type of paint called “primer.” So what is paint primer?

Paint primer is a type of paint commonly used as an undercoat. Primers are preparatory coats that go on the material to be painted first before the paint, stain, or topcoat is put on it.

Paint primers help to seal cracks, holes, and imperfections in the surface to be painted. The primer coating also helps to provide a smooth layer for the top coat to sit on.

Some paint primers even have additives that improve the qualities of the primer coating. For instance, shellac-based paint primer contains shellac which helps to block stains and moisture from bleeding through the paint from the material.

But that’s not all. Let’s go deeper into what paint primer does.

What Does Paint Primer Do?

Generally, paint primers help to seal, block stains, prevent moisture, improve adhesion, and guarantee a smooth result. However, you should know that the function of paint primer depends on the type of paint primer that you purchased.

Some paint primers like shellac-based paint primers are designed specially to seal and block stains and moisture. Concrete primers are designed to absorb into the concrete material to cover holes and cracks. Self-etching primer is used on metal to corrode the metal. So the functions of the primer all depend on the type of primer.

However, some functions cut across all types of primer. This means there are some things that all paint primers do. Let’s check them out.

1. Improving Adhesion

All paint primers help to improve paint adhesion and bonding especially on slick surfaces like plastic, glass, and metal.

Ordinarily, painting on such a surface is very difficult because the surface is smooth and the paint will not stick. But with a coat or two of primer, the paint will have a smooth undercoat to bite into. This helps to improve adhesion.

2. Sealing

Paint primers are effective sealers used to cover holes, cracks, and dents in the material.

3. Increasing Durability

Paint primers help paints to last longer on the material. Since the paint will stick better with a primer undercoat, it becomes more difficult for the paint to peel off prematurely.

4. Improving Results

Paint primers help to produce smooth and fine results after painting.

5. Protection

Paint primers protect the top coat and resulting finish from moisture, stains, and tannins in the material.

6. Primers To Cover Bright or Dark Colors

When switching from a bright or dark color shade to a lighter color, paint primer will help to cover the dark or bright existing coat so it doesn’t shine or reflect through the lighter shade when it dries.

Is Paint Primer Necessary?

Paint primer is necessary. But, you can still apply paint without priming first if the surface to be painted is smooth, even, and dry. You can also do without applying paint primer if the color you want to apply has the same shade as the existing color on the surface.

As explained earlier, paint primer helps to seal, improve adhesion, and produce a smooth result. All of these will still be achieved without coats of primer if the surface to be painted is not defective, wet, rough, or stained.

However, if the surface or material to be painted has even the slightest crack, stain, damage, or is wet, you will need a paint primer before applying the paint over such a surface. This is because the paint will not perform well on a defective surface. Also, the finish will not come out smoothly when the paint dries. So in such cases, paint primer is very necessary.

You should also know that many professional painters advise applying at least a coat of primer on a surface before painting even if the surface is already perfect. This is because the coat of primer will help to improve the smoothness of the finish when the paint dries.

So if you think about it, you can’t go wrong with a few coats of paint primer before laying the top coat. Regardless of the texture or nature of the material to be painted, a few coats of paint primer will help to produce better results. So what happens if you paint on a surface without priming first? Let’s find out.

What Happens If You Paint Without Primer?

In most cases, when you paint without primer, the finish will not come out fine and smooth. This is because without priming first,

Paint Adhesion Will Be Weak

As explained earlier, paint primers help to improve paint adhesion. When you apply a coat or two of primer before painting, the paint when applied will bite into the primer coating.

But if you don’t apply primer first, it becomes difficult for the paint to adhere properly to the surface. This will be worse if you apply paint on a slick surface like glass or plastic without priming first. The whole paint coating can peel and fall off quickly.

The Finish Will Be Rough

If you don’t prime before painting, you risk having a rough finish, especially on furniture. This is because furniture is usually riddled with nail holes, pencil marks, wood shavings, and the likes. All of which come from the carpenter’s shop while the furniture was being made.

A coat or two of paint primer will help to seal and cover all these imperfections in the furniture. If you don’t prime before painting, all these imperfections will ruin the paint. The finish will be filled with bumps and holes.

Stains And Moisture Can Bleed Through The Paint

Paint primer acts as a very good stain-blocker and moisture-resistant film on the material. If you don’t prime a stained or wet surface before painting, the moisture and stains can easily bleed through the paint causing the finish to appear stained and blotted.

Paint Cleaning Will Be Difficult

Without priming first, cleaning stains and grease off the finish will be difficult. This is because the paint will not be properly bonded to the surface since you didn’t prime first. So you risk wiping off the paint while cleaning it due to weak adhesion.

Existing Colors Can Reflect Through The Top Coat

Paint primers help to cover bright and dark shades or colors on the surface. If you paint over a bright color like red or a dark color like black without priming first, the existing bright or dark paint can reflect through the finish.

This is called bleed-through and it’s the last thing you want to happen to your freshly painted surface. So when should you use paint primer? Let’s find out.

When To Use Paint Primer?

Here are scenarios when you need to use paint primer before applying the paint:

When Switching Color Shades

When you are going from a dark shade or color to a lighter shade, you need to use paint primer to cover and prevent the darker shade from affecting the finish.

Also, when you are going from a bright color like yellow or orange to a light color, you need to use paint primer to prevent the brighter color from reflecting through the finish.

Tip: When you want to switch color shades, go for a grey primer.

When Switching Paint Sheens

Also, when you are switching paint sheens like when going from a higher sheen like semi-gloss to a lower sheen like matte or eggshell finish, you need to use a primer first.

When Working On A Fresh Material

When you are working on fresh material like fresh wood, concrete, plaster, or drywall, you should always prime before painting.

This is because fresh materials are usually riddled with patches, imperfections, and sometimes, moisture. A coat or two of the right primer will prevent moisture and patches from affecting the finish.

When The Material Is Stained

If you are working on a material that is stained, filthy, or greasy, you should prime it first. For this, always use a stain-blocking or moisture-resistant primer.

When Panting Wood Trim

Wood trims usually need at least a coat of primer for the paint to last long on the wood.

When Painting A Slick Or Polished Surface

When painting slick or polished surfaces, always use a primer with good bonding qualities as the paint will not stick well to polished surfaces.

When Painting Porous Materials

Materials like wood, plaster, and drywall are porous meaning that paint can be easily sucked in. So to prevent wastage, seal the porous material with a few coats of paint primer.

When Painting Uneven Surfaces

When painting a rough or uneven surface, always use a paint primer first. If not, the finish will also come out rough.

Now you know when to use paint primer. But when shouldn’t you use paint primer? Let’s find out.

When Not To Use Paint Primer?

Before we go into this, you should know that priming before painting is a good way to ensure a smooth and fine result regardless of the surface or texture of the material to be painted.

Here are a few scenarios when you can do without priming first.

When The Material Is Perfect

If the material is smooth, dry, and not affected by filth or stains, you can paint over it without priming first. This is because the material is already perfect enough to be painted over.

When Using The Same Color Shade

If the paint you want to use has the same color and shade as the existing paint on the surface, you don’t need to prime. In such cases, a light sanding with fine-grit sandpaper is all you need before applying the paint.

When Painting A Material That Doesn’t Require A Smooth Paint

If you are painting material and you don’t mind the type of result that you get, you don’t have to prime. You can just lay the paint but you should know that in such cases, the finish wouldn’t last long.

Do I Need To Prime Before Painting Wood?

You need to prime before painting wood because wood is a porous material and porous materials tend to suck paint.

So if you don’t prime before painting wood, chances are the paint will be sucked in and you’ll need more paint to cover the wood. This means you’ll be applying thicker coats and thicker primer coats take forever to dry.

Asides from that, wood is usually riddled with nail holes, tiny slits or openings, pencil marks, and sometimes, pests. All of these imperfections will affect the finish so before you paint wood, ensure to prime first to seal and cover these imperfections.

However, you can do without priming wood before painting if the wood was previously stained or painted with the same color shade as the paint that you want to apply. For instance, if the wood was coated with a brown wood stain and you want to apply brown paint on the wood, you don’t have to prime first.

Final Words

Overall, a few coats of paint primer go a long way in ensuring the paint applied sticks and performs well on the surface.

However, you may do without priming if the surface to be painted is already in perfect condition. Also, remember to go for a paint primer that fits the type of paint that you want to use or apply.

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