Should You Always Prime Before Painting?

Painter priming a wall with a paint roller

Sanding, priming, painting – that’s how a typical paint job goes. But what about self-priming paint? And what if the surface is in relatively good condition? Should you still prime before painting, or can you skip this step? Let’s find out.

What Is a Primer?

Primer is applied as a preparatory coat on a surface before the final paint coat. It seals the surface and creates a clean and smooth area for the paint to adhere to.

Primers look a lot like paint but they have a higher concentration of solids and an adhesive binder in them. The thicker consistency creates a uniform undercoat, ensuring that the topcoat gets fewer brush streaks, sits better, and lasts longer with a non-grainy, non-bumpy finish. Plus, primers offer protection against moisture and environmental damage. 

Types of Primer

There are several different kinds of paint primers in the market. The surface you’re painting and the paint you’re applying will determine the best primer type for your project. Let’s talk about the three main types: 

Oil-Based Primer

Oil-based primers are very versatile and are good for preparing a variety of surfaces, including wood, steel, interior and exterior walls, metal, and previously painted surfaces. 

Oil-based primers have been an industry standard for decades for their ability to prevent paint peeling, blistering, and cracking. These primers are, however, a little more brittle than water-based primers.

Use for Paint Type: Works well with both latex and oil-based paints.

Best For: Surfaces that will likely be in frequent contact with hands and fingers such as wooden sash windows, doors, metal, stairway banisters, or cupboards. And, heavily marked or stained wood. 

No-Go Surfaces: Masonry.

Corrects Imperfection: Eliminates and prevents stains.

Take Note of: These primers release high amounts of Volatile Organic Compounds or VOCs that are toxic for humans, animals, and the environment. They’re also slow-drying and need harsh thinners and solvents to clean.  

Water-Based Primer

Water-based primers, also referred to as latex primers, use acrylic resins for the base. They are super easy to work with – smooth and easy application and clean up. Latex primers have flexible formulas that allow them to expand and contract with temperature changes. 

They’re available in zero- or low-VOC formulations which makes them a safer choice for people and the environment around your home. Plus, water-based primers are quick-drying and easy to handle.

Use for Paint Type: Water, oil- and solvent-based paints.

Best For: Wooden surfaces, unfinished drywall, brick, galvanized metals, concrete, and indoor areas less likely to contact water. 

No-Go Surfaces: Outdoor and extra-exposed surfaces.

Corrects Imperfection: Rough surfaces, the acrylic resin binds and smoothens the surface.

Take Note of: Not suitable for surfaces subject to stubborn stains such as kitchen walls etc. 

Shellac Primer

This is another durable choice. Shellac paint primers are quick-drying and contain denatured alcohol solvent that helps seal in stains and odors very quickly and easily. The alcohol evaporates quickly after application and leaves a thin, hard shellac coating. This coat makes a smooth surface for the paint to settle upon.

Shellac primers are the best stain-blocking primers and offer reliable coverage. They’re super easy to apply and clean up and have a low odor too. 

Use for Paint Type: Both oil-based and latex primers.

Best For: Spot priming any surface in small patches of tough stains such as from water or smoke damage.

No-Go Surfaces: Do not work well when you cover the entire room instead of spot-priming.

Corrects Imperfection: Seals odors and stubborn stains.

Take Note of: Shellac primers soften when exposed to high temperatures and release harmful fumes. 

Why Prime?

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

Some people skip priming because they feel like it’s unnecessary and only adds more cost and time to the project. However, there are major benefits to priming a surface before applying paint. 

  • Primers are formulated to maximize adhesion, which results in better paint bonding and a longer-lasting paint job.
  • They act as a sealer for porous surfaces that otherwise absorb paint.
  • In some cases, primer application reduces the number of paint coats required for proper coverage.
  • A primer base coat strengthens the bond between the topcoat and the surface.
  • A primer coat helps cover wood grain and knots, prevents previous colors from bleeding through, and hides joints.
  • It seals the surface and aids prevention of mold and resistance to moisture and other environmental factors.
  • It creates a neutral base coat for optimal color accuracy and ensures the color stays vibrant longer. 

When To Use a Primer

Here are some instances when using a primer is recommended:

Poor Wall Condition

If your walls are troubled by mold, stains, smoke or water damage, then you need a primer before a new paint coat. Treat the problem and apply a coat of primer to clean the walls and get them ready for a fresh coat of paint. 

The Previous Coat is Glossy

Glossy surfaces cannot hold paint well because they’re slippery and there is nothing for the new paint to bind or “hang” onto. If you’re painting over such a surface, scuff the surface lightly with sandpaper and apply a coat or two of a high-quality primer. 

Although plastics and glossy paints almost always need some kind of roughening, you may even skip the scuffing part and apply primer coats. The primer will stick to the underlayer and create a better, relatively rougher, surface to grab onto. 

To Cover Imperfections

If your wall is stained, chalky, dusty, smelly, or suffering from any other defect, you’re going to want a primer. Whether the stain is from your kid’s crayon, a beverage, oil, or another hard-to-clean substance, a primer will create a clean slate over it. 

Painting Over Dark Color

Primer paint on blue ceiling
Photo Credit: Memitina / Canva Pro / License

Priming is a must when you’re going from dark to a light color. Dark colors are more saturated and will show through lighter and less saturated colors. So it’s best to prime before making drastic color changes if you want to save yourself the hassle of five or more coats to get to the desired paint color. 

Red and yellow are generally the toughest colors to hide, and the most popular primer color to cover such dark hues is gray. A high-build acrylic latex primer will hide the dark color in two to three coats. 

Painting a Humid Bathroom or Greasy Kitchen

Steamy bathrooms often collect water spots and mold stains on walls. The same goes for kitchen walls and ceilings, they gather plenty of grease splatters and spots over time. 

Painting over them will inevitably cause the blotches to bleed through the newly applied paint. 

A stain-inhibiting, sealing primer will cover the spots and give you an even-color finish. Plus, priming well before painting will also cover up odors (if any). 

Note: Primers will not solve mold or mildew issues and will only accelerate their growth. Make sure you remove and treat mold before applying anything. 

Bare Surfaces

Applying primer on a floor with a roller
Photo Credit: Ruslan Sidorov / Canva Pro / License

Porous and fresh surfaces always need a primer. This includes unfinished, bare wood, concrete surfaces, and stucco. Porosity can cause such surfaces to absorb water, oil, odor, and stain. 

Some concrete surfaces have a higher pH which can cause problems with proper paint adhesion. Certain other concrete surfaces may have efflorescence – a crystalline residue – that causes weak bonding. 

Similarly, bare wood is one of the trickiest materials to paint. When you paint unstained or untreated wood, the wood grain creates an uneven finish and the wood’s natural fiber absorbs a lot of paint. Paint soaking into the surface also creates uneven coloring. 

A bonding primer seals the surface and ensures a smooth, professional finish.

Painting Certain Surfaces

  • Wallpapered Walls: Painting on wallpaper means applying paint on a rough, textured surface. The same goes for painting a wall you striped off wallpaper from. Popping a coat of primer creates a smooth base for your top coat and ensures a longer-lasting finish.
  • Brick and Masonry: Stone, brick, and concrete surfaces tend to be porous. Such surfaces also face efflorescence issues which is a white powdery substance. Priming them before your first coat of paint seals and prepares the surface.
  • New Drywall: Brand new drywall is very porous and will absorb all the paint you apply to it. A single coat of primer can help you avoid a myriad of moisture-related issues later.
  • Swapping Surfaces: If you are going from a semi-gloss to a stain, flat, or eggshell paint finish, a primer will give a better surface for the paint to grab onto. 
  • Metal or Plastic Surfaces: Such surfaces are harder to paint either because the area is too slippery or too rusty and rough for paint to stick to. Priming metal and PVC prevents patchy, peeling paint. Pro Tip: Sand the surface before priming to create a rougher, better adhesive base. 

When To Skip a Primer

If priming seems like an elaborate job, you’ll be pleased to know there are some cases when skipping a primer coat is okay. 

Your Walls Are in Excellent Condition

You may be able to skip priming if the surface is perfectly clean or needs just a little work to return it to good condition. 

An easy and quick way to clean walls is to wipe them down with a soft cloth dipped in a mixture of tri-sodium phosphate (informally known as sugar soap). Or, simply attach a clean brush to the end of your vacuum and clean the dust and debris. 

For a clean surface, you might just need two coats of quality paint to achieve a nice, neat finish. 

You’re Painting a Darker Color Over a Lighter Shade

Using a primer is a must when going light from dark. But priming might not be necessary if you’re applying a darker shade over a lighter color base. If your existing paint job is good and is properly prepped, then just two coats will provide even coverage.

If the new color is darker, it will hide underlying imperfections and lighter tones naturally. That said, you will still benefit from using a primer, especially on porous surfaces, to prevent the old paint color from seeping through. 

You’re Using a Self-Priming Paint

The paint-and-primer-in-one products come with built-in primers and do not need a separate primer. Such paints are thicker than regular paint, and the consistency builds a dense coat. You can use a self-priming paint if your walls are in good condition.

This is because these paints essentially save you time by combining two steps into one but don’t necessarily work better than a traditional paint job. 

Spot Prime vs. Full Prime

Now that you know when to and when not to prime, let’s get familiar with two more concepts that often confuse homeowners: 

When Should You Spot Prime?

Spot priming means you apply a primer only on specific sections of the surface. It’s a common practice when the rest of the surface is in good condition and the color change isn’t too drastic. 

Spot prime when:

  • Covering repairs such as a patched blemish
  • Hiding previously unpainted sections of a wall
  • You need to hide knots or blemishes in the wood

When Should You Full Prime?

Common scenarios when you need a full prime:

  • Making a drastic color change
  • Painting unpainted or very porous surfaces (new siding, drywall, etc.)
  • You’re going from a high-gloss or stained finish to a relatively matte finish
  • Painting latex paint over a previously oil-base-painted surface
  • Painting ultra-smooth surfaces that need a primer coat to hold or grip onto

Frequently Asked Questions

What happens if you don’t prime before you paint?

For most surfaces, applying paint directly will cause the product to absorb into the surface. You will not only waste more paint but will also end up with uneven coverage, peeling, bubbling, and chipping.

How many coats of primer do I need?

The number of coats you need depends on the material and condition of the surface. If the surface is in good condition, you’re not changing colors drastically, and you’re not changing finishes, one coat should do the trick. Go for a second coat of primer if painting over a glossy surface, darker old color, or porous surface. 

Is primer thicker than paint?

Yes. Primers are typically thicker than paint because they contain more solid content to fill into small imperfections on the surface and create a better, more even base for topcoat. 

Don’t Feel Like Priming?

To prime or not to prime can be a confusing choice with any painting project. But choosing to prime will always go a long way. If the condition of your walls calls for a priming job and you’re just not up for a DIY project, call in a pro to lend you a hand.

Main Photo Credit: Olga Stock / Canva Pro / License

Farah Nauman

Farah Nauman is a freelance writer and an accountant based in Pakistan. She spends most of her time combating the South Asian heat and being a mom to her three fluffy cats and a dozen little Aloe Veras in her house.