Can You Use Exterior Primer Inside?

Using primer is an essential part to a painting project in the home. Primer helps ensure that the new color will last longer and look better than just re-painting over the old color or an un-painted wall. If you want the new surface to look great and have your friends think a professional did it, then primer is a must use.

But what happens when the only primer you have around the home is exterior primer. Can you use exterior primer inside? Yes, there is no issue using exterior primer inside the home. However, exterior primer will be more expensive and add functionality that may not be needed inside the home like mildew, temperature, and weather resistance.

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Now that we know we can use exterior primer inside the home, let’s discuss what primer is, when you need them, what are the best types, and how to use them.

What is Primer?

Primer is a specifically formulated paint product that helps prepare surfaces for a new coat of paint. The primer preps the surface to give the paint an additional layer the paint can adhere and lock into. Primer can be used on a newly painted surface or a surface that needs to be re-painted . Using a primer will help seal the pores in the wood and prevent knots, stains, and wood tannins from bleeding through the paint. The biggest reason you want to use a primer is because it will help your paint jobs look great and have the paint job last longer than if one was not used.

When Do You Need to Prime

Many people think that using a primer is unnecessary and just adds time and money to any painting project. The truth is using a primer may end up saving you time and money in the long run. Primer will ensure your painted surface will look amazing and last longer, therefore not needing to correct mistakes or repainting after a few years because it looks faded.

I would recommend using primer in any new paint project but the main two times you need to make sure a primer is a key ingredient in your painting project are:

New paint on an unfinished surface can use a good primer. It will be tempting to skip this step and just paint but the results will always be worse than if a primer was used as the base coat. If primer is not used you are risking the surfaces peeling, cracking and fading significantly earlier.
Switching paint types between oil-based and latex-based is always a reason to use a primer. Just make sure to scrape and sand the wall before applying the primer. If you fail to use a primer in this case your paint job will not look as intended. The different paint types will interact in a way that will make the surface look like an amateur did the job and in turn cracking, peeling, and fading will be in your quick future.
Surface is porous is another reason to need a primer. Using a primer will ensure you won’t need to have 3-4 coats of paint on the wall because the highly porous wall is soaking in all the paint. This will save you money and time in the long run.
Changing from dark to light color will also need a primer. A primer will make it so the old dark color doesn’t seep through the new light color being applied to the surface.
Original surface was stained is another reason to need primer to start a paint job. To make sure the stain doesn’t bleed through the new coat you will want to add a primer first, you may also want to choose a thicker primer as well.

Types of Primer

There are 3 types of primers. They are available in oil, latex, and shellac. Each type has its own benefits and drawbacks. Choosing the right type depends on the surface that needs to be covered.

Oil Primers: This is typically the industry standard. Oil primers can be used with both latex and oil-based paints. This primer can be used on a bunch of different surfaces, including wood, steel, and other metals.

This primer is great for preventing stains from showing through the new paint. Oil primers can be used on interior or exterior, unfinished or bare wood because it helps seal the pores in the wood, which enables the coat to cover the surface efficiently. Another benefit is they stop the tannins released in the wood so it won’t bleed through the paint.

Drawbacks of this primer are that it takes a long time for it to dry and it releases large amounts of organic compounds, meaning it can be harmful with prolonged exposure in small spaces. Safety precautions should be used and taken seriously when applying oil primers.

Latex Based: This type of primer is water based and ideal for using on unfinished drywall and painting. Latex based primer is fast drying and less brittle than the oil based primer, which means it will crack less. Latex based primer is especially good when applying to soft woods, brick, concrete, and galvanized metals.

Since this primer is water based, they are easy to clean and have no issues with being harmful to long exposure in small spaces. A much more healthy option than the oil based primer.

Shellac: There are some that say shellac is the best stain blocking primer. Works great for severe water and smoke damage on walls and can even seal in the smoke smell in the walls. Works well on wood, metal, plaster, and plastic. A bonus is it is fast drying and highly adhesive.

The major drawback is they give off a strong aroma and fumes and this primer is not as versatile as latex and oil based primers.

Differences in Exterior vs. Interior Primer

Characteristic	Exterior	Interior
Seals	X	X
Increases Adhesion	X	X
Creates Uniform Surface	X	X
Minimizes Cracking	X	X
Mildew Resistant	X
Weather Resistant	X
Temperature Resistant	X
Creates Longer Paint Life	X	X
Blocks Stains	X	X

Tools Needed to Add Primer

Paint Brush: Choosing the right paint brush will make the job all the more easy. Make sure you have the right sizes and enough paint brushes to get the job done. After using them visit our other article on how to take care of your paint brushes.
Paint Roller and Pan: Depending on the area you need to prime you may also need a paint roller and a pan. These will help get the job done more quickly than just using a paint brush.
Painters Tape: This is key to make sure you do not paint over the surfaces that you do not want to paint.
Drop Cloth: To ensure you do not get paint on any flooring or furniture you will want to use a drop cloth.
Ladder: A ladder will help you reach those areas you can’t reach.

Final Thoughts

So now that we know that primer is essential to any painting project, especially in the instances listed above, we can start applying the primer to the surface in need. We also know that exterior primer can be used inside, there are only a few differences between interior and exterior primers and none of the differences are harmful or will effect the look of the project. When using exterior primer inside, it may cost you more and give you additional function that you may not necessarily need indoors. But in the end, the primer will get the job done!