Difference Between Interior and Exterior Paint – Types of Coating

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Paint is a material that has been an essential part of the human toolkit for millennia, with its key purpose being to protect and decorate all sorts of surfaces. Not all paints, however, are created equally. We have a wide variety of paints to choose from, all of which are designed for specific purposes and environments. Among the great menagerie of paints that we have at our disposal, the two most common are interior and exterior paint. While they may look or even smell similar, there are several key differences in their formulaic composition, their properties, and their intended applications. In this article, we will be exploring the difference between interior and exterior paint.

What Is Interior and Exterior Paint?

Before we get into the discussion of the difference between interior and exterior paint, allow us to first construct a working definition for either medium. While there may be some crossovers in the information in this section and the one pertaining to the differences between the two mediums, we feel it is important our readers get a more holistic understanding of them. So, allow us to provide definitions for interior and exterior paint before moving on to their differences.

What Is Interior Paint?

As the name would suggest, interior paint is a type of paint medium designed for application on indoor surfaces such as walls, ceilings, floors, and trim. To make it suitable for indoor use, It is produced with specific properties that produce low VOC emissions and allow for painless maintenance. There are many different types of interior paint available on the market. The most common variety of interior paint is either water-based or solvent-based. They can also often be referred to as latex or oil paints. Water-based paints are largely easier to clean up and produce far less odor during application. Compared to solvent-based paints, they also dry a lot quicker.

However, solvent-based paints have the benefit of being much more durable and resistant to moisture, scratches, and scuffing. Thus, the latter is more suitable for areas that experience high volumes of traffic.

You can find different types of interior paint that produce different finishes. Flat, eggshell, satin, semi-gloss, and high gloss are all options available to you in this regard. The types of interior paint you work with should depend on the level of sheen and durability you require. Flat paint offers nothing in the way of sheen but is the ideal choice for hiding imperfections on the surface and can be used to create a matte aesthetic. Satin and eggshell finishes, on the other hand, have a bit more of a sheen and can be much more durable compared to flat paint. This is what makes them more suitable for high-traffic areas within the household. Semi-gloss and high gloss finishes have, as the name would suggest, a much higher sheen and are able to provide superior durability and resistance to moisture. This lattermost option is more suitable for application on trim, doors, and cabinets.

Materials such as drywall, metal, plaster, and wood pair really well with interior paint. This paint medium can be used to invigorate and improve the aesthetics of a room, hide any imperfections, or introduce a new atmosphere. In addition to this, interior paint is able to safeguard and extend the life of an object’s surface by sealing it. The sealing properties of interior paint will inhibit moisture and stains from penetrating through and into the object.

A key plus side of interior paint is its unbeatable cost-effectiveness. Better yet, using interior paint is an incredibly easy way to transform a room into something more beautiful, thus increasing its overall value. Interior paint administers a decorative layer with utilitarian protective values. It is thus useful for most aesthetic and utilitarian purposes. The air quality of an indoor space can also be improved through the use of interior paint. It not only reduces VOC emissions but also prevents mold and mildew from growing on surfaces. Maintenance and efforts in cleaning are also made simpler when surfaces are covered with interior paint, which acts as a durable and easily washable surface that is resistant to both wear and stains.

When it comes to decorating and protecting indoor surfaces, interior paint is absolutely essential. The wide variety of different finishes, colors, and formulas also makes it easy for one to find the paint that best suits their needs and preferences. Interior paint can be used as a means to upgrade the aesthetics and atmosphere of an indoor space. It can also increase the overall value of a space while also providing its functional value.

What Is Exterior Paint?

Exterior paint is essentially the opposite of interior paint in that it is designed for outdoor applications. It is typically used for the decoration and protection of external surfaces. Exterior household objects such as doors, shutters, sidings, and trim all require this sort of paint. The properties within exterior paint make it fit for use as something to protect outdoor surfaces. These properties include, but are not exclusive to, UV protection, durability, and water resistance.

There are several different types of exterior paint available on the market, with the most common being water-based or solvent-based in terms of the vehicle they use. Water-based paints are much easier to clean up since they are more soluble. They also produce less odor and have a quicker drying time than solvent-based paints. This being said, solvent-based paints do tend to be more durable and moisture-resistant, which is ideal for items and objects that remain exposed to external elements.

It would be ideal to use solvent-based exterior paint in areas with high humidity, fluctuating temperatures, or precipitation.

Just as is the case with interior paint, the many types of exterior paint are available in numerous finishes. These include flat, semi-gloss, satin, and high gloss and the option you pick should be based on the level of durability and sheen required by the job. If you are trying to hide imperfections or produce a matte look, flat paint would be ideal as it has no sheen. When coating exterior trim, doors, and shutters; satin and semi-gloss would be ideal as they offer better durability. They also produce a slight sheen. High gloss finishes produce the strongest sheen and offer superior durability and resistance to moisture. Metal surfaces such as railings and gutters are where high gloss exterior paint finished would be most ideally used.

Exterior paint is suitable for use on a variety of different materials such as metal, wood, masonry, and even stucco. All sorts of exterior paint can be used to revive and modernize the look of a building, offer it protection against the elements, and improve its curb appeal should you wish to put it on the market. Importantly, the properties within exterior paint help it protect the surface against moisture and UV damage, which can otherwise lead to rot, decay, and fading if not abated with a protective coating.

This is the key benefit of exterior paint; its provision of a protective barrier against the elements and shifting climatic conditions allows for better longevity of the surfaces to which it is applied. Another benefit of exterior paint would be its ability to improve energy efficiency. It does so by reflecting heat and light that hits the building, thus reducing the amount of solar radiation that enters. As we have said, exterior paint improves the curb appeal of buildings. Along with the protective qualities it provides, exterior paint can greatly improve the financial value of your property.

The Difference Between Interior and Exterior Paint

Now that we know what interior and paint are, as well as a bit about their functions and purposes, we may begin to detail the various key differences between the two products. In this section, we will be covering the main differences between their composition, properties, and application methods.

Composition

One of the foremost differences between interior and exterior paint lies in the composition of either material. Since they are designed for different purposes, the materials that make up each paint type vary according to this. You will find that interior paint is normally water-based with some exceptions being solvent-based. Exterior paint is primarily solvent-based on account of the durability requirements of outdoor use. Water-based paints can also be referred to as latex paints and contain water as the primary vehicle and solvent. They also contain various pigments for color, resins for bonding requirements, and additives that provide their properties.

Solvent-based paints, which may also be referred to as either oil-based or alkyd paints, typically contain organic solvents such as turpentine, mineral spirits, or toluene to dissolve the pigments and resins.

Traditionally, solvent-based paints are used for exterior surfaces on account of their superior durability and weather resistance compared to paints made with water-based vehicles. This being said, water-based paints have evolved in their functionality over the past few years to the point where many now provide good coverage, reliable durability, and superb color retention for interior walls and ceilings.

Properties

Another major difference between interior and exterior paint is in the properties of either material. The primary purpose of an interior paint finish is to produce a smooth and even coating that can be maintained and cleaned without difficulty. A good quality interior paint should be resistant to staining, easy to scrub without scuffing, and easy to clean any mess off.

The amount of volatile organic compounds (VOCs) present in interior paint is also kept to a minimum, which has the benefit of making it safer for indoor usage.

This not only makes it safer to work with during application but also allows for a healthier environment for pets and children. As mentioned, interior paint comes in a few different varieties to give you ample options to choose from. Just keep in mind that the flat paint option is not as resistant to stains and scrubbing compared to the glossier varieties.

Exterior paint, as the name most keenly suggests, is designed for outdoor use where durability is much more of a concern. Exterior paint contains properties that allow it to withstand the harsher conditions that surfaces would not be exposed to if indoors. For instance, exterior paint needs to be durable enough to withstand UV radiation, harsh weather, fluctuating temperatures (day/night and seasonal), and moisture.

The viscosity of exterior paint is typically much thicker as it contains a greater volume of binder and pigment compared to what one would find in your standard interior paint. One major drawback of exterior paint is that its properties cause it to have a substantially higher concentration of VOCs. This makes exterior paint a lot more flammable, dangerous to inhale without proper protection, and ultimately more hazardous, hence why it should not be used in indoor settings. Exterior paint also comes in a similar variety of different finishes. The glossier finishes of exterior paint tend to provide the highest degree of durability and resistance to moisture, but they do tend to highlight imperfections instead of covering them up. Additionally, it can prove difficult to evenly apply glossy exterior paint evenly.

Application

The compositional and property differences between exterior and interior paint lend to each having its own recommended application processes. The most ideal spaces for the use of interior paint would be on surfaces located indoors where it will not have any exposure to harsh weather conditions, temperature fluctuations, moisture, and UV radiation. There is no benefit or merit to applying interior paint to outdoor surfaces because the protection it provides would not prove adequate enough. When exposed to the elements, interior paint would peel, fade, and crack quickly and easily.

Provided that the surface you are painting is sheltered and out of the way of direct sunlight or rain, interior paint might be suitable for outdoor use.

Outdoor areas that one could coat in interior paint include eaves, overhangs, and well-covered porches. It is, however, more prudent and pragmatic to simply use exterior paint in outdoor spaces since temperature changes and moisture will still affect well-sheltered areas in outdoor spaces. Interior paint can typically be applied under any temperature conditions provided that there is ample airflow running through the workspace.

Exterior paint, however, should be applied exclusively in outdoor settings when temperatures rest between 50 – 90 degrees Fahrenheit. Humidity levels also need to be low so as to prevent the impediment to the proper curing and drying of the coat. The formulation of exterior paint ensures superior adhesive qualities, flexibility to withstand shifting temperatures and climates, and durability strong enough to withstand harsh outdoor conditions.

However, to ensure that proper adhesion is achieved, surfaces should be cleaned, sanded, and primed before exterior paint is applied. Since exterior paint is not designed to be cleaned and scrubbed as effortlessly as interior paint, it is crucial that this is done before painting to guarantee its longevity.

The Importance of Picking the Right Paint

Deciding upon the correct type of paint is a crucial step toward ensuring that your project is a success and will stand the test of time with little need for maintenance. Surface, location, and environmental factors are all things to consider when deciding upon the paint type, finish, and color you are going to work with. If you are unsure which type of paint works best for your current project, you can always consult a professional painter or paint store for expert guidance on what to do.

It is always worthwhile to invest in higher-quality paints and to properly prepare surfaces before application. By doing so, you will better ensure that you are left with a beautiful and durable finish that will remain beautiful and undamaged for years to come.

In conclusion, interior and exterior paint are similar yet very different in terms of their composition, properties, and even their application. In essence, they are designed for use in two very different environments. Interior paint should be used indoors, whereas exterior paint should be applied in outdoor settings. Interior paint contains fewer VOCs, making it safer for use inside the household. The high degree of durability required by exterior paints lends to them containing a high concentration of VOCs, which makes them too hazardous for indoor use, but tough enough to withstand the environmental factors of the outdoors.

Frequently Asked Questions

What Is Interior Paint?

Interior paint, as the name suggests, is designed for indoor use as a means to decorate and protect the interior spaces of a building. The most ideal spots for interior paint to be used include surfaces located in hallways, kitchens, bedrooms, and bathrooms. The benefit of using interior paint on indoor walls lies in its exceptional coverage, its lack of VOCs and other harmful chemicals, and the aesthetic qualities of its finishes.

What Is Exterior Paint?

Exterior paint is designed to provide durable protection against the harshness of outdoor weather conditions. Surfaces covered in exterior paint should be protected against UV radiation from the sun, moisture, and fluctuating temperatures and climates. Exterior paint also contains properties that provide protection against mildew and the growth of fungus. Additionally, it is resistant to fading. However, exterior paint contains high concentrations of VOCs, which makes its use indoors unsafe and why it should only ever be used outside.