How many coats of primer?

Why do you need a primer?

Primer essentially acts as a base coat so that paint can better adhere to different surfaces and materials. It also doubles as a sealant, preventing primed surfaces from completely soaking up paint.

Primer can also be used to cover up small dents, cracks, and chips which helps produce a more even and smoother finish. If you are thinking how many coats of primer do I need? Keep reading.

What happens if a primer is too thick or too thin?

Primers are by no means replacements to actual colored paint. Their primary function is to seal and let paint better adhere. Using a primer makes it easier to paint and reduces the likelihood of blotching and from having to apply to many topcoats to have a smooth and even finish.

However, too thick of a primer coat can lead to uneven and slow drying, dripping, and a very rough surface finish. Likewise, too little primer results in poor adhesion that can lead to chipping and peeling.

What are the considerations before applying primer to wood?

There are things to consider before deciding on how many coats of primer on wood surfaces is required.

1. Unfinished wood/painted wood. Unfinished wood should always be primed as it’s quite porous and will quickly absorb paint which leads to uneven coats. You can paint wood without priming only if you are using paint of a similar shade or color. For instance, you’ll need to remove paint from wood, here’s how.
2. Wood quality. Old and weathered wood will likely have spots with mold and mildew. These must 1st be cleaned before priming. You also need to fill in holes and deep scratches with wood epoxy to ensure that you’ll have an even and smooth surface.
3.  Wood color. You need to prime wood if you plan to paint it. You’ll need the help of a primer so that paint better sticks to the wood’s naturally rough and uneven surface. And to minimize the amount of color needed for a consistent finish later. This is a good move if you either plan on coating wood with a paint of similar shade or one that is an extreme contrast.

What are the considerations before applying primer to metal?

1. Unfinished metal/painted metal. Clean the surface with mineral spirits to remove any grease that may affect paint adhesion. Metal painted with a glossy finish must first be sanded and wiped clean. If you need to remove paint, here’s how you can do so.
2. Metal quality. Primer on metal can prevent rust formation, but any existing rust must first be removed. Any dents, holes, and scratches must be mended using the appropriate bog/ fillers before priming.
3. Metal color. Some metals, like copper and brass, do not have a neutral color and can easily peer through unprimed paint, affecting the overall tint and shade. Priming metals like these reduce the chance of discoloration.

What are the different types of primers to use?

Latex

This type of water-based primer is commonly used on concrete and drywall. They also work well for softwood and galvanized metal.

Oil-based

Oil-based primers are commonly used on wood as it seals the porous surface and prevents wood tannins from showing through the paint. These are also great for metal as oil adheres better and will not cause rust, unlike water-based primers.

Shellac-based

Shellac primers work well with a lot of materials including wood, metal, and even plastic. They are better stain blockers than oil-based primers and can even mask the smell of old stains.

Should you use self-priming paints?

“Paint and primer in one” or self-priming paint is a tempting option especially if you want to cut down on costs. However, It’s rarely advisable to use self-priming paints as they are often thicker than normal paint.

Self-priming paints are known to have poor adhesion, which can cause more problems later on. Only use self-priming paints on pristine surfaces. Other than that, it’d be better to go with traditional paint and primer.

Do you need to remove an old coat before priming? And how?

The general answer is no. You only need to remove old paint coats if they are already heavily compromised. Spots such as cracks, peels, bubbles, and blisters should be removed before priming to prevent your new coat from suffering the same results.

Use tools like paint scrapers and razor knives to remove paint by hand. Use power tools such as a disk sander, corded heat gun or a specialized tool like the Wagner PaintEATER for more arduous tasks.

When to use only one coat?

Only use one coat if the surface is in good condition and is thoroughly cleaned. The color of the new coat should also be close to that of the old one. Painted surfaces with a glossy sheen always need at least one coat of primer to ensure good adhesion.

When to use more than one coat?

Are you wondering how many coats of primer to cover dark paint? Use more than one coat if you are transitioning from a dark to a lighter shade or if the surface is heavily damaged. Porous surfaces such as wood, drywall, and spackled spots may also need more than one coat.

How many coats of primer and what primer to use?

Different surfaces can require different amounts of primer and paint coats in order to really bring out their luster. Additional layers of coating also acts as protection, increasing the durability of whatever was painted. Deciding on how many coats of primer to put on painted wall or surfaces depends if it’s concrete or drywall.

On drywall/plaster

Drywall absorbs more paint than it should. Latex primers work best with drywalls as they even out surface imperfections, spackled spots, and seams from joint compounds. Here’s how many coats of primer on new drywall is needed. Apply one or two coats of primer depending on the quality of the surface. You may only need one if the drywall is skim-coated.

On interior trim

Oil-based primer is recommended for unpainted trim, while either latex or oil-based primers can be used for painted ones. How many coats of primer to use on wood trim? Use one coat if the trim is unpainted or if you’re using paint of a different color. No need to prime if you’ll be using the same color/shade.

On interior wood

Oil-based and shellac primers work best for unpainted wood, while all 3 types can be used on painted wood. Only one coat is needed unless the wood is heavily stained.

On timber cladding

The number of coats depends on the type of primer you’ll be using. Use one coat when using oil-based or shellac and two coats with latex-based wood primer.

On a medium density fibreboard

You almost always have to prime MDF since it’s very porous. It typically requires at least 2 or 3 coats as the paint will seep through on the first 2 coats. It’s recommended to sand the material in between primer applications to obtain the best finish.

On a car body

If you’re wondering how many coats of primer on metal car bodies, you should have least two to three coats of specific oil-based primers made with epoxy or urethane that form a hard and rust-resistant surface.

On fiberglass

Fiberglass doesn’t need to be primed. If you do want to prime it, apply only a thin coat of oil-based primers such as epoxy or urethane.

On wooden boat

Using an oil-based marine primer, apply 3 coats under the waterline and 2 coats for the other parts of the hull.

On outside Aluminum

Apply a single coat of self-etching primer. This is a special primer formulated to micro-etch the aluminum for the paint to adhere to.

On outside steel

Before priming, the metal must be thoroughly cleaned of any rust, dirt, and residue. Primer for metal surfaces can then be applied using a brush, spray gun, or roller.

On a concrete/masonry wall

Here, masonry primer is usually applied using rollers or brushes to ensure an even coat. After, it must be left to completely dry for at least 24 hours. If patches appear, you’ll need another coat of primer.

Tips for priming

• As with painting, apply the primer in suitable lighting conditions.
• Additional primer coats are usually only done when paint coats have blotches or when the old color peers through the new paint.
• You can get your primer tinted close to the new paint to ensure that the color stays true.
• Use latex primer when transitioning from oil-based to water-based paint.
• If more than two coats of a specific type of primer are not enough to provide a good painted surface, consider changing to a different one.
• Don’t mix different primer types.

Safety precautions

Some primers may include certain chemicals that can irritate your skin if you accidentally touch it. Be sure to wear gloves and safety glasses, as well as some added protection such as an apron and closed shoes. 

Avoid working in an enclosed area or one with poor ventilation as some primers can emit strong and toxic fumes. Keep the windows open and wear your mask while working.

Conclusion

With only minor setbacks, it’s easy to see why priming is such a crucial step when painting. Not only does it make painting on different materials and surfaces easier, but also provides an added layer of protection which helps preserve both the quality and longevity of your workpieces.

Investing in good quality primers and knowing how and when to use them definitely helps save you a ton of time and resources. In the end, what you should be after is to keep all your projects in prime condition for as long as possible.