While the topcoat of a paint job is what we see, there was a lot of proper preparation under the surface to achieve this look. The most crucial part of this preparation is, arguably, the primer. It is a preparatory coating applied to a surface before painting, whose primary purpose is to enhance the paint’s adhesion to the surface. Its proximity to paint makes it easy to believe that paint and primer are interchangeable. But is primer a paint?
Primer is a paint product that improves the finishing characteristics of the finishing paint. Apart from improving adherence, it gives a smoother final look and reduces the number of paint coats that you need.
Pigment, one of the main components of paint, is absent in primer.
Painters often use primer in conjunction with paint, and this article takes a close look at the differences between these two, the pros and cons of using each one, and how to use primer on different surfaces correctly.
What Is a Primer?
Primer is a preparatory coating applied to surfaces before painting, mainly to allow the paint to adhere to the surface better than if you used the paint alone.
A primer creates the base needed to achieve a perfect paint job. Compared to paint, primer is not intended to be the outermost finish. However, manufacturers can engineer it to have better binding and filling materials with the material underneath.
So, what exactly does primer do?
- It helps to cover surface imperfections and provides a uniform, even surface for the paint to adhere to.
- Conceals and blocks stains to prevent bleeding through to the final coat of paint
- It neutralizes the color of the surface to allow the most authentic, purest color of the paint can shine through.
Some situations in which you should use primer include:
- When applying a lighter color to a darker colored surface. This application gives a neutral base that allows the full saturation of the paint to shine through.
- If the area you are painting is humid and more susceptible to mildew and leaching.
- If there are stains on your surface, you want to prevent bleeding through to the final coat of paint.
- On very porous surfaces.
- If the previous coat is glossy, a light scuffing with sandpaper and a coat of primer will help to improve adherence since glossy bases do not hold paint well.
You can also choose to tint the primer so that it more closely matches the color of the paint. If the final coat of paint is a deep color, tinting is a great way to reduce the number of coats of primer that you will need to achieve uniformity.
What Is a Paint?
Paint is a pigmented composition that converts to a solid film on application to a surface. Water-based paints have water as a solvent and are commonly referred to as latex paints (though they contain no latex).
On the other hand, oil-based paints have a solvent of mineral spirits or alkyd resin.
Water-based paints are fast-drying, more environmentally friendly, and clean up easily with water and soap. Oil-based paints are best suited for areas prone to heavier use, such as floors and cabinets.
They are more expensive than water-based paints, need to be cleaned with chemical solvents, and have a strong odor.
There are five main components of paint as expounded on below
Pigments are finely ground solids incorporated into the paint to contribute color. You can mix different pigments to form other colors. There are two types of pigments: natural and synthetic.
The pigment is arguably the most vital part of paint. Some of the functions that pigments serve in paint include offering color opacity, film cohesion, an appealing aesthetic to the paint, eliminating the previous substrate’s color, and protecting the film by reflecting destructive UV light.
As pigments are typically solids, you cannot use them by themselves. They would be difficult to apply, not stick, and wash off the surface after getting wet. Binders stick the pigment particles to the surface and each other.
Binders are the film-forming component of the paint and are preset in all paint variations. The properties that binder impart to paint include its flexibility, gloss, toughness, and durability. While some binders come from natural oils, today’s binders are mainly from synthetic plastics.
Another critical use of filler is to lower the cost of paint as it costs less than prime pigments.
The filler, sometimes known as the extender, is a cheaper compound added to the paint. Fillers work to thicken the paint fil, increase the paint volume, and support the paint’s structure.
The amount of filler present in paints is not constant and varies. Some paints do not contain filler, while others have vast proportions of filler.
While the binder does bind the pigment particles together, the resulting mix is thick and difficult to spread. The solvent works to make the pigment and binder into a less viscous fluid that you can apply easily.
The solvent evaporates after laying out the paint, leaving a dry, evenly-applied paint behind.
Solvents are typically resting at the top of paint as a thin fluid with the pigment and binder underneath. This settlement pattern is what makes stirring paint before using them so important.
Additives are chemical substances added to the paint to modify some of its properties. Some examples of paint additives include:
- Ceramic substances to improve the strength and durability of the paint
- Fluorescent pigments for glow-in-the-dark properties.
- Defoamers to prevent the formation of entrapped air bubbles
- Plasticizers increase the paint’s flexibility and minimize the film’s cracking.
Primer Vs. Paint?
At a glance, paint appears identical to primer since they are both substances applied to a surface. However, there are several distinct differences between paint and primer, in terms of composition and purpose, among others.
Below are some ways in which paint differs from a primer.
As mentioned before, paint contains pigment, binder, and solvent; the pigment provides color, the binder sticks the pigment particles together, and the solvent increases the mixture’s viscosity.
On the other hand, primer consists of a solvent, a synthetic resin, and an additive agent. A significant difference between these two substances is that primer does not contain any pigments, although some do have polyethylene to increase durability.
The primer’s primary function is to act as a bonding agent that improves the adherence of paint to the surface and helps create an even, smooth look for the final layer of paint.
It is a preparatory coating applied before painting and is not meant to be the outermost layer. Paint, however, is designed to be the outer layer that provides protection and adds aesthetic appeal to the surface.
Paint and primer each have their advantages and disadvantages essential in understanding these two substances and how and when to use them.
Pros of Using Paint
- Rust and corrosion prevention for metal surfaces
- Thermal protection from paints that offer heat resistant coatings
- Painted surfaces are much easier to maintain than non-painted surfaces
- You can use special paint coatings to protect exterior surfaces from extreme weather conditions such as salt air corrosion and acid rain.
- Aesthetic appeal. You can use paints of different colors to improve the appearance of a surface.
Cons of Using Paint
- Some paints may need repainting often as they get dirty easily
- Applying paint can be a messy process that can stain furniture, floors, and surrounding spaces.
- Depending on the paints you use, some paints take a much longer time to dry.
- Some paints release VOCs (Volatile Organic Compounds) harmful to your health and the environment.
Pros of Using Primer
- It helps improve paint adherence to the surface
- Seals pores and imperfections on the surface
- Prevents bleed-through of stains to the paint surface
- Neutralizes the surface color to help the actual color of the paint shine through
- It helps to reduce the number of paint coats you need to achieve full coverage
Cons of Using Primer
- Oil-based primers may take longer to dry and increase the time spent working on your paint project.
Can You Use Primer as Paint?
Primer is mainly designed to help paint adhere to the surface and not act as the outer cover. So, we do not recommend using a primer as paint. However, an excellent substitute for this is self-priming paint.
Self-priming paint is paint that has primer mixed into it. You can eliminate the priming step from the painting process with it. Paint-and-primer-in-one is much thicker and has a higher build, giving a sturdier paint coat.
So, when should you use self-priming paints?
1. On Interior Surfaces
Self-priming paints work best on interior surfaces not exposed to the stress of outdoor conditions such as UV rays, snow, temperature, and humidity.
2. When Repainting
Repaints are ideal for using self-priming paints if you previously painted the surface in the same color as the self-priming paint.
If you do not want to paint new, unfinished drywall without the hassle of painting separately, self-priming paint is a good alternative since you must prime new drywall.
While self-priming paints are indeed a convenient and efficient option, there are circumstances where you would be better off just using a regular primer. These situations include:
- If you are working on a more complex and challenging paint job such as auto detailing or industrial metal.
- Suppose you are painting over a glossy surface with less glossy paint. A regular primer will help cover the glares from the surface to get a more consistent result.
- If you would like to paint over oil-based paint using acrylic or latex
- A traditional primer is almost always the best option for new surfaces you have not painted before.
Can I Just Use Primer and No Paint?
I do not recommend using a primer as the final coat of paint. Primer bonds well with paint, but you should not permanently expose it to the environment. Left uncoated, primer is susceptible to water damage and rapid wear and tear.
Also, primer comes with a flat sheen to improve the bonding between the topcoat and substrate; this does not hold up to rain, dirt, sun, and other environmental factors as much as glossy paints.
If left uncoated for extended periods, the primer will deteriorate and break down into a chalk-like substance. Since primer is also stickier than paint, dust particles and debris may stick to the wall and make it look shabby.
How Long Can Primer Go Unpainted?
Paint is usually applied after the primer has dried completely. The drying times for primers vary depending on the type of primer and the surrounding climatic conditions such as humidity and temperature.
Most latex primers will be dry to the touch after 30 minutes to an hour, though it can take longer to dry completely.
However, can you leave the primer unpainted after it dries? And for how long can you leave primer unpainted? You can leave latex primers unpainted for thirty days and oil-based primers for about 14 days.
After that, you will need to reapply primer to the surface before you paint. The primer manufacturer will usually indicate how long the primer can be left unpainted, and different brands will have varying time frames.
If you do not want to reapply primer, you can opt to sand down the primed surface until it is smooth, though this will likely be more work than re-priming.
How to Prime Wood
A wood primer is a preparatory coating applied to wood and other wood-related surfaces such as plywood before applying the paint. The primer is formulated to bond to the surface and ensure that the finished paint looks consistent and smoother.
While primer is necessary for any painting project, it is especially so when working with fresh wood that you have never painted before or with weathered and old wooden surfaces.
Some of the arguments for using a primer include:
- Primer has a high solids content that fills the wood grains and makes the final look smoother.
- It helps with the paint adhesion. Primer adheres to wood better than paint, while paint sticks to the primer better than bare wood, which gives a better bonded final product that is durable.
- Primer also works to prevent bleed-through of stains, an ability that is vital when working with certain types of woods, such as knotty pine.
- Priming provides an opaque base for painting that makes brighter colors appear more vibrant.
So, if a primer is vital to painting wood, what happens when you skip it and go straight to painting? Since most woods absorb primer and other finishes quite unevenly, your first coat of paint will appear blotchy.
The water in the paint will also raise the wood grain, depriving you of a smooth finish. While the second paint layer may correct or hide these problems, your paint will start peeling around year one.
If you are painting wood that tends to stain and bleed through, you will begin seeing stain marks on your paint after a while, which will ruin your paint job’s aesthetic appeal.
The steps below provide a guide to applying primer on wood.
Step 1: Prepare the Wood for Priming
Preparation is a critical step before you apply anything to the wood. Your final look will only be as good as the surface you applied it on. If the wood already had paint, start by scraping that away with a putty knife.
After removing the existing paint, use some good quality wood putty to fill in areas with deep gouges and cracks, then sand down the area after the putty dries and hardens.
After sanding off the area to which you applied putty, you can then sand the entire surface to open up the grain and get an even feel.
Start with fine grade sandpaper such as 80 or 100 grit before finishing with 150 grit sandpaper to get the wood ready for priming. As you sand, remember to work with the grain of the wood and not against it.
You can then use a vacuum to thoroughly remove all the sanding dust and wipe down the surface using a tack cloth.
Step 2: Apply the Primer
Before applying the primer, be sure to tape and cordon off any areas you do not intend to paint. If using the primer raises the grain of the wood, you might want to consider sanding with fine-grit sandpaper before applying the final primer coat for an even look and feel.
Follow the manufacturer’s instructions on how many coats of primer to use and the time t wait between coats. When applying the primer, the application method is primarily a matter of personal preference.
While spraying it on is faster and easier, you will need more coats to get a more even coverage. On the other hand, Brushing creates a thinner and more even base for your paint.
How to Prime Wood
How to Prime Concrete
The dull, gray color of concrete can make a space seem drab, cold, and uninviting. Fortunately, concrete’s versatility offers several options to lift its color and improve its appearance, such as painting. However, using a primer is your best bet to get the best results when painting.
A primer on concrete will
- act as a bonding agent between the concrete and the paint, increasing adhesion.
- Prolong the paint job’s life.
- Fill any pores on the surface to create a more even and uniform surface for painting.
Another crucial reason you need a primer on concrete is due to efflorescence, crystalline salt deposits that can form when there is water on concrete. Efflorescence makes it much harder for the paint to adhere to the concrete surface and can cause paint to decay and chip if you do not use a primer.
Although you can use a universal primer on concrete, primers specifically made for concrete will offer better performance. Some of the concrete primers you can use include:
Because of concrete’s porosity, acrylic or water-based primer is more likely to soak into the concrete and create a bond that allows the paint better grip.
This is a type of latex primer designed for harsh work environments and to resist chemicals. They are not typical for residential applications.
This masonry primer protects against efflorescence, lime burn, and discoloration. You can use the primer on properly cured, new concrete.
Acrylic Block Fill
This primer is also used on smooth, unpainted, or new split face concrete blocks. However, this primer is for bare blocks and not for blocks with a cement parge coat.
The following steps offer a comprehensive guide on how to prime your concrete surface.
Step 1: Clean the Concrete Surface
You cannot skip this step for most other surfaces, and concrete is no different. The porous surface of the concrete is porous and tends to trap oil, dirt, and grease.
Start by sweeping away any surface debris such as leaves and debris. Scrub away any gunk that is stuck to the concrete. Pull out any vines, moss, and other plants covering the surface.
If there are any areas with dense grease areas, mix some TSP (Tri-sodium phosphate) with water in the recommended ratios, wash away any oil stains and rinse it off when you finish. A pressure washer works great to clean large concrete areas, especially when working outdoors.
Step 2: Fill In Any Defects
You want your concrete to be as smooth as possible to get the best final look. If you have defects in your concrete, such as gouges and cracks, fill them up using concrete filler.
Smooth away any excess and sand the gap after the filler dries. If there is any structural damage, you can also fix it using quick-setting or hydraulic cement.
Step 3: Seal the Concrete
As mentioned above, concrete is a very porous material, and trapped moisture in the paint can rise and destroy your paint job. You can counteract this by using a concrete sealant.
The sealant is crucial for indoor concrete. It may not be as necessary if you are painting outdoor concrete. Follow the instructions of the manufacturer for preparation and application.
Step 4: Prime the Concrete Surface
Ensure that the primer is compatible with both the concrete and the paint you plan to use and the concrete surface location (indoors or outdoors). Before applying primer, you should also ensure that the surface is completely dry to provide the best possible adherence.
To check if the concrete is sufficiently dry, place a small piece of plastic wrap on the concrete surface and use tape to seal the edges. Leave it overnight and check if the plastic has condensed moisture the following day.
If there is condensation on the underside of the plastic wrap, allow the concrete another day and test again. Apply the primer when you get no condensation.
While you can apply one coat of primer, if the concrete surface has a bright or concentrated color or working on outdoor concrete, you can use more than one coat of primer.
How to Prime Metal
While priming metal is not more or less any difficult than when working with other materials, you must make some unique considerations for the best result.
Chief of these concerns is the tendency of a metal to rust and oxidize. Any primer that you use should be specially formulated to address this. The following steps will give the best prime job when working with metal.
Step 1: Set Up a Working Space
Working around rust particles can pose a health hazard to you, so work in a well-ventilated room and go outdoors if possible. Wear the appropriate personal protective equipment as you work, such as gloves and a dust mask, which becomes essential if stripping paints containing lead.
Also, ensure that you have a damp cloth nearby to regularly wipe away rust and dust particles as you work instead of waiting until you finish.
Step 2: Remove Any Rust and Old Paint
Start with a wire brush or a nylon brush to remove any flaking paint and as much rust as possible. If a manual brush is not working as well as you expected, especially on highly degraded surfaces, you can attach a wire brush attachment to a brush and use that.
Step 3: Clean the Metal Surface
You can easily clean metal surfaces indoors using a clean cloth, some clean water, and a mild detergent. Removing the grime and grease build-up is vital to the paint adhering to the surface.
If the metal was predominantly outdoors, you might need to use a pressure washer to clean the surface, particularly in areas with mildew, mold, or an excessive build-up of grease. Even if the exterior looks clean to the naked eye, you must go through this step.
Apart from detergent, you can also use mineral spirits to clean up grease.
Step 3: Sanding
Use 600-grit sandpaper to smooth the surface and scuff it up to promote primer adherence to the surface. Wipe down the surface and remove any lingering debris.
Step 4: Apply Primer
If the metal has rust, start by applying a zinc-chromate primer to the metal surface before applying the regular primer. Zinc chromate is resistant to corrosion, and using it closest to the metal surface will protect the metal from rusting.
After applying this, you should apply the regular primer immediately. The type of primer you use will depend on the paint you plan to use. Ensure that the two are compatible. Below is a guide to determine which primer to use in which circumstances.
- If the metal surface is non-ferrous (the metal does not contain iron), you can test this with a magnet; if the magnet does not stick to the surface, it is a non-ferrous metal), use a galvanized metal primer. Do this also for surfaces that you leave exposed to the elements.
- If the surface is ferrous, we recommend using a rust-inhibitive primer even if you have not yet had any issues with rust.
- Avoid using water-based or latex primers if you often expose the surface to moisture. Moisture quickly soaks through primers requiring another paint job every couple of months.
Since metal is highly susceptible to oxidation effects, we recommend that you apply at least a double coat of primer. Two coats of primer will significantly reduce the impact of exposure and time to the metal surface.
Video On Priming a Metal:
How Long After Priming Should You Paint?
After application, primers need to be allowed time to sit, and you cannot apply paint over primer immediately. The time you need to wait before painting is a sweet spot of not too little time that does not allow the primer the required time to dry and not too long that the primer deteriorates.
Primers’ ideal drying times can vary wildly between brands, room conditions, and other factors discussed below.
1. The Thickness of the Primer Coat
Sometimes, thin coats of primer are not sufficient to fully cover the imperfections on the surface you are painting, and you may need to go in with a thicker coat or even a second coat of primer. Both of these will increase the time you need to wait before applying paint.
2. The Type of Primer
Depending on the solvent it contains, you can use different types of primers. While oil-based primers are excellent in sealing porous surfaces, they take longer to dry than other types of primers, so you will need to wait longer before painting. Latex primers dry much quicker, and you can even paint over them in an hour.
3. The Surface You Are Priming
Some surfaces, such as new drywall and stained wood, may require more coats of primer that will then translate into a longer waiting time before painting.
4. Environmental conditions
Room conditions such as temperature and humidity will also affect the drying time of the primer. High humidity and cool temperatures will slow down the drying process.
I recommend an optimum temperature of 25 degrees Celsius and relative humidity of approximately 50 percent.
We cannot overstate the importance of applying primer before you paint. Its advantages are innumerable and the reasons not to use it few and far between. You can also get primers tailored to different surfaces to get the best results. Still, the question remains,
Is Primer a Paint?
As mentioned above, primer lacks one of the critical components of paint-pigment- but it is a preparatory paint product applied to prepare a surface for painting.
Thank you for reading this article, and we hope that it has been informative and answered any questions you had. You can interact with us in the comment section below, and we would love to hear your questions, thoughts, and suggestions.