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When it comes time to tackle a home improvement project like painting your house, you may not be aware that these days, exterior paint and interior paint are two very different things. That was not always the case: as recently as 20 years ago, they were considered virtually interchangeable by professional painters. However, thanks to technological advances, the chemistry of indoor paint varies greatly from that of outdoor paint. It is essential that you use the right type of paint in order to ensure the highest levels of durability for the job it is meant to do. Let’s take a look at some of the ways exterior and interior paint differs from one another.


Before any comparison can occur between interior and exterior paints, it is important to understand the general ingredients that go into any can of paint. A concoction of chemicals blend together in a solvent, which evaporates after the paint has been applied to a surface. These chemicals include polymers, which form the surface of the paint; binders, which prevent the paint from separating and also, as their name suggests, help bind the paint to the surface; and pigments, which give the paint its color. Additives are mixed in to help improve such things as drying time, weather resistance, and paint distribution within the paint solution.


The chief difference between the ingredients in interior and exterior paints is the additives. Exterior paints contain additives that help them to better withstand weather conditions and sun exposure, while interior paints contain additives designed to help them resist abrasion. Another major difference between the ingredients used in interior and exterior paints is the levels of VOCs, or volatile organic compounds. Paints which contain higher levels of VOCs are always used outdoors.


Interior paints sometimes contain organic pigments, which have been known to fade noticeably if used on exterior surfaces. Meanwhile, exterior formulas of paint do not use organic pigments, making them more able to withstand the elements and decreasing the need for frequent repainting.


The binders used in exterior formulas of paint are typically formulated to make it more resistant to cracking, as well as provide increased moisture control to ward off paint damage due to precipitation. Interior paint binders, on the other hand, are designed to make the paint more resistant to abrasion.


The liquid used to hold the paint together differ greatly from the exterior formulas to the interior ones. Interior paints are required by federal guidelines to contain the lowest possible levels of VOCs in their solvents, as these compounds can cause both short- and long-term health problems and may even be associated with certain types of cancer. The EPA allows exterior paint to have VOC levels as much as 2-5 times higher than interior formulas of paint, since the health risks are reduced by the circulating outdoor air.

When you choose paint for your next project, make sure you pay attention to whether the can says it is for interior or exterior surfaces. Care to have a pro tackle your paint job instead? Call Total Package Painting today and let us help you with all your residential interior or exterior painting needs. We are Shelbyville, KY’s number one choice for high-quality house painting. Contact us today for a consultation!