A Beginner’s Guide to the Different Kinds of Interior and Exterior Paints

Different paints have their own different properties. These properties are what make them suited for different parts of a building.

While paints for building or home interiors are made to resist staining or are made to be scrubbed for easy cleaning, exterior paints are made specifically to resist harsher environmental factors, such as fading and mildew.

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What’s in the Paint?

In order to fully understand the difference between interior and exterior paints, you have to know beforehand that paint is essentially composed of the following things:

• Binder (typically resin, which holds the pigment to the surface),
• Solvent (which reduces the paint’s viscosity for better application),
• Pigment (which gives the paint its color and opacity),
• Extender (which improves adhesion in the paint), and
• Additives (which modify the paint’s properties).

Solvents and pigments in both interior and exterior paints are similar in a lot of ways. For instance, you can use either water- or oil-based paint for outdoor paint jobs, as the binders and additives in the paint make it so that they resist external factors such as prolonged exposure to heat and rain.

However, they also have their differences. For instance, oil-based paint is almost used exclusively as an exterior paint because of the difficulty in cleaning up, as well as the strong odors and potential fumes, and most interior paints are water-based because of this.

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Interior Paints

Interior paints are made to be cleaned easily and resist staining, which means that the binding resins are rigid to keep the paint from getting scuffed or smeared. This usually means that interior paints are water-based, which in turn makes them safer for indoor use.

Interior, water-based paints also have a few other advantages, such as having a faster drying time and are easy to clean up using water.

Exterior Paints

Exterior paints are made to resist mildew and fading, as prolonged exposure to heat and rain are more likely to fade interior paints. Aside from the attractive gloss of oil-based exterior paints, they also have a smooth, durable finish.

The secret lies in their binders (aka resin), which are softer to allow the paint to better resist not just the previously mentioned environmental factors, but also peeling and chipping.

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Which One to Use?

At the end of the day, the primary difference between the two is the solvent. There are certain paints that can be used for both indoors and outdoors, but they do have their own tradeoffs despite their versatility.

To know which paint is best suited for the job, be it oil- or water-based, always be sure to consult a professional painter or talk to a professional painting firm where a representative can walk you through everything that you need.