Home Improvement

Understanding The Difference: Exterior Vs Interior Paints

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By John Wick

Different paints have different properties because they are created for different purposes. The formulation depends on whether it is for exterior or interior painting.  Also, they need to withstand different circumstances. Therefore, they are usually different in their composition.

To understand the distinction between these, you need to understand the chemistry behind both of these types. The major difference in their purpose is the motive of exterior paint is to endure inclement climate. For instance, resisting mildew, mould, fading, chipping, cracking, and more. On the contrary, interior paint’s job is to resist tints and be wiped clean without causing any damage.

Now, let’s take a look at the chemistry of both types and understand how specifically they differ from one another:

The Basics

The formulation of all the paints is similar; they all contain the same fundamental ingredients. The ingredients include additives, resins, pigments and solvents. The ingredient that results in the wetness of paint is the solvent. The solvent evaporates when the paint starts to dry. The rest is the leftover components that are resins, pigments, and additives.

The pigment gives the paint colour. On the other hand, additives give it different properties, for example, mildew obstruction. Lastly, resins bind the paint to the surface. Resins are typically made of epoxy, acrylic or silicon. Let’s proceed to the difference between the exterior and interior paints.

Toxin Levels

A crucial difference between interior and exterior paint is that interior one is always made to lessen VOCs. VOCs that are often called Volatile Organic Compounds, are breathable toxins that are released after the application of paint. These are bad and toxic for humans. In interior painting, low VOC is extremely important because of its application in our living areas. Contrary, for exterior paint, we have less exposure to these toxic compounds as they’re outside. Therefore, in exterior paintings, the toughness of the paint is prioritised over being Low VOC.


Depending on the finish you have selected for your house, interior paints are normally simple to clean. But, exterior walls are usually difficult to clean as they are water-proof.

Dry Time

Oil-based paints, usually for interior painting, tend to dry slower than water-based paints, which are for outside paint. Also, paints outside in the open air will dry quicker than the paints inside with no continuous airflow.

Moreover, heat from the sun will also make the outside paint dry quicker. Therefore, when you assemble all of these aspects, exterior paint normally dries faster, especially if it’s water-based.


If we talk about adhesion, both exterior and interior paints give satisfactory adhesion. Still, exterior paints adhere good enough to go through all kinds of rugged climates. A claim that interior paints cannot copy. Generally, exterior paints last longer and stick better in comparison with interior paint. 

Weather Resistance 

Exterior paints need to be proficient to undergo a variety of climate conditions. It includes salty sea breezes, temperature variations, UV radiation, and more. External paint includes flexible polymers that keep the excellent look of the paint. Meanwhile, the surface base broadens and contracts. It is to adjust according to the changing conditions that paint on exterior walls withstands. 

Moreover, exterior paint includes chemicals that help in preventing mildew, fading, and tannin stains. Exterior paint comprises additives that make it endure exposure to the weather. 

On the other hand, in interior paint, these ingredients are not present. Interior paint contains binders that help it in resisting scraping. Interior paint is made with more protected resins because there is no exposure to toin. Also, it is less likely to be subjected to an intense freeze. These resins help in protecting interior paint from scraping and make it easier to wash or clean.

Also Check: How to become an Interior Designer


Solvents are liquid substances. It suspends the components so that you can put the paint on the ground. In water-based paints, primarily, the liquid is water. But, in oil-based paints, the liquid is paint thinner. It is formulated from a variety of solvents. It could include turpentine, acetone naphtha, mineral spirits etc.


Exterior paint is composed to endure years of trouble from the weather fluctuations. Firms make them tough enough to not scrape off from contact. For example, if twigs are thrown against your home by the bugs flying or wind into the wall. As such, it’s way more lasting as compared to interior paint. Though, interior paint is quite durable as well. It can also withstand occasional cleaning and scrubbing.

Bottom Line

As a final statement, some paints can be utilized both outdoors and indoors. These universal paints are exceptionally versatile. However, they do come with their drawbacks. Suppose you’re not sure about which sort of paint you should take. You can consult any professional painter. Initially, interior and exterior painting may seem the same. But just when you correlate them based on their ingredients. For example, additives, purpose, and environment; you can effortlessly figure it out.

These kinds of details are available real handy when you go to purchase them.  Therefore, whenever you intend to purchase paint, look at the tin properly to get a detailed picture of the components.