The Similarities Between Interior Paint and Exterior Paint
Before learning the differences between interior and exterior paints, it’s helpful to understand the similarities. All paints are made of pigments, resins, solvents, and additives. Pigment is used to give paint its color; it can be made of finely ground organic or synthetic materials. Resins are used to bind the paint to the surfaces that are being painted. A solvent is a liquid that is added to paint to make it easier to apply. The solvent is typically either water (such as in a water-based paint like latex or acrylic paints) or mineral spirits (found in oil-based paints). Additives give paint specific properties, like being resistant to moisture and mildew or having a faster drying time.
While all paints have resins, they don’t all contain the exact same resins. The same can be said about pigments, solvents and additives. To ensure that interior paints achieve great results indoors and exterior paints achieve great results outdoors, each type of paint has a different formula.
The Difference Between Interior and Exterior Paints
While interior paint and exterior paint are both designed to bring color and style to your home or business, there’s a difference in how they accomplish this task. Interior paint is designed to make your home look its best through resistance to stains and scrubbing, ensuring it looks great even after spills or cleaning. Exterior paints are designed to make the exterior of your home look its best through resistance to fading, cracking, mildew and more troubles brought on by exposure to the elements. Here’s a look at how interior paint and exterior paint differ when it comes to pigments, resins, solvents and additives.
Pigments
Paint gets its color from pigments, which are finely ground materials. There is organic pigment, which tends to be brighter in color, and synthetic pigment, which tends to be duller in color. Organic pigment is typically used in interior paint, while synthetic pigment is most commonly used in exterior paint.
Organic paints are safer to breathe (although you should still make sure the room you’re painting is well ventilated) and don’t have harsh odors, making them a great choice for indoor painting projects. However, some organic pigments will fade in the sun, so they’re not ideal for projects on the outside of the home.
Pigment in exterior paint needs to be more durable and able to withstand the elements. For this reason, outdoor paint is often made with synthetic pigments, which aren’t as likely to fade in the sun or heat. However, synthetic pigment can create harsh odors that you wouldn’t want inside your home, so it’s best to keep these paints outside.
Resins
Resin is the ingredient in paint that binds the pigment to the surfaces that are being painted. Resins are commonly made of acrylic, epoxy or silicone. Since exterior paint is exposed to the elements, its resin must be softer and more flexible, allowing it to adjust as the material it covers expands and contracts with changing temperatures. Resin in exterior paint is also designed to resist cracking, chalking, moisture and more. Additionally, resin in outdoor paint cures with sunlight, while resin in interior paints does not.
Alternatively, paint for your home’s interior isn’t exposed to direct sunlight, rain and other weather conditions, so its resin is more rigid. This helps protect the paint from damage caused by scuffing and makes cleaning easier, since the resin can tolerate scrubbing.
Solvents
A solvent is added to paint to make it easier to use and spread around. Water-based paint is made with water as the solvent, as the name suggests. Examples of water-based paint include acrylic paint and latex paint. Water-based paints can be used both indoors and outdoors.
Oil-based paints are usually made with mineral spirits – a liquid made from petroleum – as the solvent. These paints are typically used outdoors. Oil-based paints have a strong odor and can be trickier to clean, making them better suited for exterior paint projects. Alternatively, water-based paints don’t have such a strong odor and are easier to clean, making them a smart choice for indoor painting.
Water-based paint also has a shorter drying time than oil-based paint, so it’s more convenient to use inside where you’d like to be able to use the room again as soon as possible.
Additives
Additives are substances added to paint to give it certain characteristics. For example, exterior paints have additives that protect the paint from the elements, such as water resistance, mildew resistance, or substances that make the paint less prone to fading due to sun exposure. Since interior paints don’t need to be able to withstand severe weather, they typically don’t contain these additives.
Additionally, since indoor paint doesn’t have the additives required to stand up to the elements, it would not stay in quality condition outside as long as exterior paint specifically designed with the weather in mind.
There’s a lot to know when it comes to choosing the right paint for your interior or exterior painting projects. When you’re not sure which to choose or simply don’t want to send your time and energy painting your home yourself, Prim Painting’s got you covered. We offer residential and commercial painting services as well as a free quote, a two-year warranty on most projects, custom designs and professional results. Click here to contact us or request your free estimate.