What is Primer Paint?

painting primer white on a cement wall

When you get started with your painting project, there’s one word you’ll definitely come across: primer. What is it, and why is it necessary? Is it really worth the extra step? Let’s uncover the role that primer plays in the longevity and beauty of your paint job. 

What is Primer Paint?

Primer is a base coat that helps create a smooth, even surface for paint to adhere to. Its thick consistency improves the durability of the paint and enhances its overall appearance. 

Having a smooth surface to paint on prevents brush marks and imperfections. It also helps to seal porous surfaces, prevent stains from bleeding through, and provide a consistent base color for your paint. 

Why You Should Prime

primer painting on a wooden wall
Photo Credit: Joe_Potato / Canva Pro / License

Priming is an essential step in the painting process, as it helps to create a beautiful paint job and extend its lifespan. The main reasons you need to prime are to hide stains, create a smooth base surface, and help your paint job last.

To Hide Stains

Paint primer acts as a barrier between the surface and the paint, effectively hiding any stains or discolorations that may be present. It’s usually cheaper than paint, so if you want to save money covering up those stubborn stains, primer is a great option.

To Create a Smooth, Non-Porous Surface

A surface that is porous or too glossy will not allow the paint to adhere properly, resulting in a less durable finish. Primer helps to create a smooth and non-porous surface, allowing the paint to bond effectively. Additionally, primer can also help to fill in any small imperfections or cracks on the surface, providing an even and flawless base for the paint. 

To Help Your Paint Last

Primer not only helps the paint adhere better, but it also helps to prevent peeling and chipping over time. By using primer, you’re helping your paint last and stay looking fresh for a long time to come. Oil-based primer is especially effective at this.

Which Primer is the Best?

So you can just buy any primer and get started, right? Not quite. There are different types of primers available, each designed for specific surfaces and purposes. Below, we will discuss some common types of primers and their uses:

Type of PrimerBest ForDon’t Use For
Oil-based primerDurable, long-lasting finish; especially on wood, metal, and windows.Masonry.
Water-based primerEase of use and clean up, especially on walls and ceilings; quick to dry.Outdoor and extra-exposed surfaces.
Shellac primerSpot-priming interior imperfections.Big exterior paint jobs or surfaces in hot temperatures (fume hazard).
All-in-one paintSaving time and money, this product can be used on a variety of projects.Surfaces in severe weather conditions.

Oil-Based Primer

Best for: A durable finish on commonly used surfaces, especially heavily marked or stained wood, metal, and windows.
Don’t use for: Masonry
Estimated cost: $36 per gallon

Coffee tables, cabinets, and doors are a few examples of surfaces that we use every day. And over time, your everyday life becomes engrained in them. However, using the right primer can slow down this process. 

Oil-based primers are ideal for surfaces that will come into frequent contact with people. It’s great at preventing stains. Moreover, they’re also suitable for heavily marked or stained wood, metal, and windows.

On the other hand, oil-based primers aren’t suitable for masonry. Masonry surfaces require a different type of primer that will adhere to their unique texture and composition. Additionally, oil-based primers dry slower, are more expensive, and are higher in VOCs (volatile organic compounds) than alternatives. They’re also more brittle and need solvents for cleaning.

However, it’s necessary to note that their effectiveness and durability outweigh their cons. They’re still the best choice for the right projects.


  • Works with both latex and oil paints.
  • Prevent peeling, blistering, and cracking.
  • Versatile; works on a variety of surfaces.
  • Durable and long-lasting.
  • Provides an unmatched, strong foundation.
  • Reliable.


  • More brittle than water-based primers.
  • High in VOCs.
  • Slow-drying.
  • Needs solvents to clean.
  • More expensive than water-based primers.

Water-Based Primer

painting primer on a ceiling
Photo Credit: Memitina / Canva Pro / License

Best for: Easy to use and clean up, especially on walls and ceilings, but also on unfinished drywall, brick, galvanized metals, concrete, and indoor areas less likely to contact water. Plus, it’s affordable.
Don’t use for: Outdoor and extra-exposed surfaces.
Estimated cost: Starts at $17 per gallon

Water-based primers are great for interior applications such as painting walls, ceilings, and furniture. They’re also a good choice for sealing porous surfaces like drywall and wood, providing a smooth and even base for paint.

Perfect for beginners, water-based primers are easy to apply, clean up, and dry quickly. Plus, their lower cost can allow you to save some bucks. Moreover, if you want to avoid that unpleasant smell of VOCs, there are low-VOC options available. 

However, it’s not all rainbows and sunshine, even when it comes to water-based primers. Even though they have so many advantages, their strength and durability simply don’t match those of oil-based primers. Additionally, this primer isn’t the best for surfaces likely to stain often, like kitchen walls.


  • Works for water-, oil-, and solvent-based paints.
  • Variants that are low in VOCs are available.
  • Smooth application.
  • Easy to apply.
  • Easy cleanup.
  • Flexible formulas that work well with varying temperatures.
  • Quick-drying.
  • Less expensive than oil-based primers.


  • Not as strong and durable as oil-based primers.
  • Not ideal for surfaces that stain often.

Shellac Primer

Best for: Spot-priming interior imperfections.
Don’t use for: Big exterior paint jobs or surfaces in hot temperatures (fume hazard).
Estimated cost: $79 per gallon

Shellac primer is another champ at durability, albeit only for interior jobs. It’s best used for spot priming. And because it’s not flexible, it’s only a suitable option for covering up small spots outside.

Nevertheless, Shellac is quick-drying, easily covers up imperfections, and creates a smooth surface. It’s also easy to apply and clean up. Furthermore, though it has a bit of an odor, it dries quickly. 

One thing to certainly be wary of is that shellac primer may release harmful fumes when exposed to high temperatures. The temperature causes the paint to soften, creating a hazard.

However, this paint has another con: its cost. Although it brings great benefits to the table, it’s typically more expensive than other primers on the market.


  • Works for both water- and oil-based paints.
  • Durable and long-lasting.
  • Creates a smooth surface.
  • Reliable.
  • Odor quickly goes away.


  • Not as versatile as water-based paint.
  • Give off a stronger odor than water-based paint.
  • Not suitable for exterior use.
  • Expensive compared to other options.
  • Not ideal for covering entire surfaces (but can be used to do so, as long as they’re interior).

All-in-One Paint

Best for: Saving time and money, this product can be used on a variety of projects.
Don’t use for: Surfaces in severe weather conditions.
Estimated cost: $40 to $100 per gallon

All-in-one paint is a type of paint that combines sealer, paint, and primer in one. It’s designed to save time and effort by eliminating the need for separate priming and painting steps. Additionally, it offers a convenient solution for small projects or touch-ups. 

However, all that convenience comes at a price. Although affordable, all-in-one paint may not last as long as regular primed paint. Also, remember that it needs multiple coats.


  • Saves time and money.
  • Available in multiple finishes. 
  • Smooth application.
  • Easy to apply.
  • Easy to clean.
  • Quick to dry.


  • Not the most durable.
  • May crack in severe weather.
  • Needs multiple coats.

How Much Primer Do You Need?

Now you know how much approximately primer costs per gallon. But how much do you need to buy? You want to avoid inconvenient trips to the store in the middle of your project. However, open primers and paints don’t last forever, so you don’t want to get more than you need either. 

As a rule of thumb, 1 gallon of primer covers approximately 400 square feet (that’s one coat). However, account for any rough surfaces and multiple coats.

You can use our formula to estimate how much paint and primer you need for your walls.

When Should You Prime?

worker hand painting primer on wall
Photo Credit: inga / Canva Pro / License

Most of the time, you can’t go wrong with using a primer. But here’s when you should definitely prime:

  • If the surface is porous: Paint doesn’t like porosity. Porous surfaces, such as bare wood, drywall, or masonry, tend to absorb paint unevenly, resulting in an inconsistent finish. Using a primer helps seal the surface and create a smooth base for the paint to adhere to. 
  • If the surface is glossy: Another thing that affects adhesion is your paint sheen (learn more about paint sheens). Glossy walls can be difficult for paint to adhere to properly. The best solution is to lightly sandpaper the surface and use two coats of a high-quality primer. But even without sandpapering, using a primer will make a world of difference.
  • If the surface has imperfections: Using a primer is a necessity to fix cracks, uneven texture, or damage. Walls in poor conditions need a primer for that extra boost of paint adhesion. 
  • If you’re painting over a dark color: When it comes to priming, your paint color plays a part. Primer can help block out the dark color underneath your new coat and create a vibrant finish.
  • If you’re using latex paint over previously oil-based painted walls: The primer will provide a necessary barrier between the two types of paint, ensuring proper adhesion.

Here’s when you should avoid priming:

  • If your wall is perfectly smooth: If you have a wall in perfect, smooth condition, you may able to skip using a primer.
  • If you’re painting a dark color offer a light color: If you’re painting a dark color over a light color, you may not need to use a primer as the light color may provide enough coverage. Nonetheless, if you want to ensure a flawless and long-lasting finish, using a primer is still your best choice.
  • If you use self-priming paint: If you want to save time and use self-priming paint, there’s no need for an actual primer.
  • If you only need to spot-prime: If you only need to hide blemishes, you don’t need to apply a full coat of primer.

To read more about when to prime, check out our article Should You Always Prime Before Painting?


Can primer prevent mold and mildew?

No, ordinary primer doesn’t prevent mold and mildew. You need to take proper measures to deal with humidity and prevent mold and mildew growth. If you simply paint over them with primer, you might make them worse. However, there are special primers available that have mold and mildew-resistant properties.

What is the best type of metal primer?

Oil-based primers are best for metals, windows, and wood.

What is the best primer for DIY painting projects?

Water-based primers work great for DIY projects because they’re easy to apply and clean. Plus, they’re affordable. They’re especially great for painting walls and ceilings, but also other surfaces, like unfinished drywall, brick, galvanized metals, concrete, and indoor areas less likely to contact water.

However, they don’t do as well as oil-based primers on metals, window frames, and wood, and they’re not suitable for the outdoors.

Additionally, if you’re looking for a durable primer for small spots indoors, a shellac primer is an even better choice.

A Paint Job With a Smooth Finish? Look No Further.

DIY projects are fun and satisfying. However, doing all your home improvement work yourself can be a hassle, so why not get help with your painting project? Contact a painting pro near you.

Main Image Credit: Prapat Aowsakorn / Canva Pro / License

Judith Gallova

Judith Gallova is a freelance writer living in Slovakia. She found her passion for writing when she created her first blog at the age of 10. Later on, she started working in marketing, and eventually combined her writing and marketing skills to become a freelance writer. In her free time, she often studies the Bible, goes to the gym, spends time with loved ones, and enjoys all things art and design.