What Is The Difference Between Interior and Exterior Paint?

It’s possible that you don’t see much of a difference between interior and exterior paints. They seem to be very close, don’t they? However, because of how they are used and how they must work, there are major variations. 

Since they are made for various purposes, different paints have different properties. Mildew and fading resistance is built into exterior paints. 

On the other side, interior paint is designed to be easy to clean and stain-resistant. To distinguish between these two forms of paint, one must first understand the chemistry of each.

Interior and Exterior Paint Chemistry

Both paints are made with the same basic ingredients which is as follows:

  • Resins: The paint is kept to the surface by resins. Silicone, acrylic, and epoxy are the most common materials used.
  • Additives: Paint additives improve the physical properties of your paint, such as water resistance, UV resistance, and durability.
  • Solvents: The solvent is the part that makes paint “wet.” When the paint dries, this ingredient evaporates.
  • Pigments: The pigment is responsible for the color of the paint.

Key Features of Interior Paint

The following are the key features of interior paint:-

👉 The aim of interior paint is for decoration and aesthetics. At the same time, interior paint adds dampness resistance, easy to wash, and ease of upkeep.

👉 Interior paint is designed to withstand abrasion. It is built to be more fragile than exterior paint because it shares space with people.

👉 The interior style of paint is stain-resistant and scrubbable. It doesn’t have any fade-resistant properties because it isn’t exposed to sunlight. It also does not need sunlight to heal. 

👉 It’s also machine washable. It’s easy to clean roller and brush marks, as well as marks and spots left by children and pets.

👉 Low or no volatile organic compounds are needed in interior paint. This lowers health risks and is important for maintaining indoor air quality.

Key Features of Exterior Paint

👉 The exterior paint is subjected to a variety of environmental conditions. As a result, it must protect against precipitation from rain and snow, as well as ultraviolet radiation from sunlight. It must also guard against fungal growth.

👉 Fading and mildew resistance is built into the exterior paints. They must be fade-resistant since they are exposed to UV radiation as well as extremely high temperatures.

👉 Soft resins are used in exterior paints. They are also very adaptable as a result of this. As a result, they are resistant to cracking during contraction or expansion. This enables them to withstand the negative effects of moisture and temperature fluctuations.

👉 The exterior style of paint can be applied to a variety of substrates by simply adjusting the sheen. A house’s exterior absorbs small quantities of water during rain. Flat paint will not bubble, allowing water to escape.

👉 Exterior paint is dangerous for indoor use because it releases more volatile organic compounds. It also needs sunshine to heal.

Is it possible for you to use Interior paint outside?

Resins and additives are the key distinctions between interior and exterior paints. Interior paints’ binding resins are stiff. They avoid stains and make interior paint cleaning a breeze. 

Vinyl acrylic resins are used in interior paints to increase scrub resistance and washability. When used on external surfaces, however, interior paint suffers from a lack of such environment-specific additives. Exterior paints are designed to survive in harsh weather conditions. When used to paint the exterior of your house, interior paint does not last as long as exterior paint because it lacks heavy-duty additives.

Is it possible for you to use Exterior paint inside?

For many people, using exterior paint indoors seems to be the natural solution to these common problems, and although it is possible, there are some serious considerations to be made.

Given that bathrooms are subjected to regular humidity and moisture stresses, the issue of whether or not exterior paint should be used in a bathroom seems reasonable. 

Moisture buildup in the bathroom can cause wall damage, and even worse. In the walls, there is mould and mildew. This can happen if there isn’t enough ventilation (for example, if there isn’t a window in the bathroom or if there isn’t a bathroom fan), but using exterior paint inside will prevent these problems. However, there are certain precautions to take into account, as it can be extremely dangerous if not used correctly.

👉 Paint fumes, also known as Volatile Organic Compounds (VOCs), are the most active chemical in outdoor coatings and can be very dangerous if inhaled. 

👉 When using an automatic paint sprayer, this is much more likely because the paint is misted into the area rather than applied directly to the wall. 

VOC’s job is to keep the pigment in the paint in place and to tie it to the surface to which it’s applied. As a result, the quality and function of an outdoor coating are dependent on this potentially hazardous aspect. 

These VOC fumes are not only harmful for the atmosphere, but they can also be toxic to humans and animals if inhaled. Lightheadedness, headaches, and nausea are all common symptoms of VOC inhalation.

👉 People with weakened immune systems are more vulnerable to VOCs’ adverse effects and may experience respiratory problems as a result. So, if you’re curious if you should use exterior paint inside, take the necessary precautions before doing so. Illnesses can worsen, leading to cancer and other life-threatening illnesses.

To prevent the effects of exterior paint on the inside, take the following precautions.

  1.  Check to see if your room is adequately ventilated.

Lack of ventilation is the number one risk factor when using exterior paints. Do not continue with the project if the area you are working in is sealed or does not have adequate ventilation. 

Painting interior walls with normal emulsions is the same, and it should be done as part of the planning process rather than after the job is finished. 

Just use exterior paints indoors if you can adequately ventilate the area with several fans, open windows and doors, and breathing apparatuses. 

It’s also worth noting that you should always keep the lid closed because fumes can easily escape and cause more damage. As the paint dries, more fumes are released into the air, so give yourself plenty of time to ventilate the area after the job is completed.

  1. Choose the appropriate paint type:

Latex that is manufactured with a water-based solution has a lower VOC content. Oil-based coatings, on the other hand, have far higher VOC levels. 

Ask an expert at your local store about the best kind for your home and check the specifics online about what you’re thinking of using to find out how high the VOC level is.

Is mixing exterior and interior paint a good idea?

Yes, but it is not advised. One is made of oil, and the other is made of water. Blisters can cause a lot of problems because they don’t dry properly. 

Exterior water-based paints are now available; you can blend water-based interior paint with water-based exterior paint, but do not mix paint with emulsion.

You can learn here > how to paint glass windows.

What is the difference between interior and exterior paint?

Now we’ll look at the distinctions between these two major paint styles. Both can change the colour of whatever surface you use them on, but that’s about it for the similarities.

PropertyInterior Paint Exterior Paint 
Type of resinPaints for the interior adhere to epoxy and silicone binding resins.Acrylic is used as the binding resin in exterior paints because it has an exceptionally tight bond and has the most toughness, but it has a strong odour.
PigmentsInterior paints use organic pigments to avoid adding additional chemicals to the mix. There are no unpleasant odours and they are perfectly safe to inhale.Exterior paints are more concerned with longevity than with keeping out harsh chemicals, so you’ll find non-organic pigments in exterior paints that can help intensify strong odours and fumes, but they don’t disappear as easily.
Additives UsedInterior paints don’t need as many additive chemicals so they don’t have to contend with as many potentially hazardous conditions.Exterior paints must be able to withstand a wide range of conditions, debris, temperatures, and other factors. Additional additives are used to aid in this, such as those that help the paint avoid fading, adapt to changing temperatures, and even prevent cracking. Mildewcides are also used in exterior paints to help avoid the growth of mildew, mould, and algae.
WeatherabilityInterior paints aren’t designed to withstand harsh or shifting weather. They have poor temperature resistance, low water resistance, and fade easily in sunlight as a result of this.Exterior paints are designed to withstand all of these factors, making them weather-resistant.
LongevityInterior paint isn’t very long-lasting, but it does survive scrubbing and washing on occasion.Exterior paint is designed to withstand years of exposure to the elements. It’s also made durable enough to withstand impacts from the elements, such as twigs blown against your house or bugs flying into the wall. As a result, it lasts much longer than interior paint.
PhysicalDamage ResistanceThe interior paint would most certainly chip off if it takes a direct blow, revealing the old paint or bare wall underneath.Exterior paint can be chipped as well, but it’s much more difficult due to the stronger resins that bind the pigment to the surface.
VOC LevelInterior paints contain very few VOCs, and some are completely free of them.Exterior paints are often high in volatile organic compounds (VOCs), which can release into the open air outside.
Adhesion PropertyInterior Paints have lower adhesion than exterior paint.Exterior paints have a greater adhesion to the surface and last longer.
Time to paint dryIt requires more time than the exterior one.Paints that are oil-based dry more slowly than paints that are water-based. Paints that are left outside in the open air, on the other hand, can dry faster than paints that are left inside with no continuous airflow. Finally, heat will hasten the drying of the paint. When all of these factors are considered, exterior paint typically dries faster, particularly if it is water-based.
Resistance to FadingInterior paint isn’t intended to be exposed to direct sunlight. Since there are no additional additives to avoid fading, the organic pigments in interior paint can fade easily.Exterior paint additives are designed to avoid fading and also protect against UV rays.
Effect of temperature Interior paint is only meant to be used in a limited temperature range of 60 degrees to 90 degrees Fahrenheit.Paint for the exterior is designed to withstand a wide range of temperatures. It must withstand the cold of winter and the heat of summer, as well as all temperatures in between.
Price Interior paint is less expensive, but it does not have the same level of durability and security.Exterior paint is usually more costly because it contains more additives, chemicals, and holds up longer.

Conclusion

Paints with different properties can be used for different purposes. Their distinct formulations are based on their primary protective capabilities. 

Homeowners may be confused by the variety of paint choices available for both the interior and exterior of their home. 

It’s safer to use paint that’s specifically designed for the surface you’re painting, whether it’s inside or out. Of course, you can still use an interior or exterior paint to eliminate all the ambiguity.

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