Can You Use Interior Paint Outside?

benefit of interior paint vs exterior paint

Many homeowners save leftover interior paint from old projects. There are plenty of reasons for this – you could have accidentally overestimated your needs, decided not to complete a second coat, or bought some backup paint. No matter the reason, the fact is that many of us wonder how to use all of this extra paint. 

Other interior painting projects are an excellent way to use old paint. However, you may be wondering, can I use this interior paint to repaint some outdoor patio furniture, an outdoor wall, or other outside fixture? Technically, the answer is yes; while you can paint over anything, it is not advisable. Read on to learn more about interior paint and its properties. We will discuss interior paint is best suited for use inside the home and what happens if it is utilized outside. 

The Basics: What Ingredients Make Paint?

interior paint vs exterior paint

To understand why you shouldn’t use interior paint outside, let’s first understand what paint is made of. It only consists of a few ingredients, so the proportions and quality of each are critical to producing good overall paint. The primary ingredient, the base, of any paint is called a solvent. A solvent is either oil or water. Oil-based solvents are often used in exterior paint designed for outdoor use and generally not in interior paints. However, water-based paints are commonly chosen for indoor or outdoor purposes. 

The next ingredient of paint is pigment, which gives your paint its color. Then there are additives. Mixing different additives provides the paint with particular properties or physical effects such as water resistance, sun resistance, increased durability, or scrub ability. 

When any paint is applied, it quickly starts drying. This is the solvent, or base, evaporating. It leaves behind the pigments and additives, which are bound to the newly painted surface by resins. Standard resins are acrylic, epoxy, and silicone; however, exterior paint needs harsher, stronger resins to bond paint more securely to surfaces subjected to the elements, weather, and other outdoor use. 

Interior Paint: What Is It?

Interior paint is paint formulated exclusively for indoor use. It uses a water-based solvent and organic pigments that are safe for humans and animals. Using organic pigments for color eliminates harsh odors and makes the paint low in volatile organic chemicals (VOCs) and other harmful substances. Additionally, indoor paint uses epoxy and silicone resin, which is less durable than the acrylic used in exterior paint, meaning it has less strength and adhesive power.

Interior paint does contain some additives, but only enough to help it withstand daily use. It is scrubbable and washable without being damaged, as well as stain-resistant. However, it has limits – it cannot be constantly wet or scrubbed as it has low water resistance and is not as durable as exterior paint. 

A paint intended for indoor use also fades in direct sunlight. This is due to the addition of organic pigments, which lose their color quickly if exposed to UV. Additionally, it is more susceptible to flaking, cracking, and chipping than exterior paints. It also has low-temperature resistance, which is why it is used in climate-controlled inside areas. To find the perfect interior paint for you, check out the wide selection at Sherwin Williams

Exterior Paint: What Makes It Different

Exterior paint is designed specifically for outdoor use, primarily painting the outsides of different buildings and surfaces. Exterior paint is either water or oil-based solvents and uses chemical pigments. Non-organic colorants don’t fade as quickly when exposed to sunlight or harsh elements. However, they do contain more powerful chemicals that are not safe for indoor use. 

In addition to chemical pigments, exterior paint has different additives than interior paint. It has harsher resins, usually acrylic binding resins, that help the paint dry so that it better adheres to surfaces than other, weaker resins. Exterior paint also has extra additives such as mildewcides, which help prevent mold and mildew on buildings. However, these chemicals come with a cost – they have intense odors and cause off-gassing as the paint is drying. The majority of the off-gassing happens in the first few days after the application but can continue slowly for years. These chemicals and VOC gases are unsafe and can cause respiratory issues when inhaled. 

Exterior paint is made with these resins and additives to increase its durability. It stands strong against years of rain, sleet, snow, and other inclement weather. It takes beatings from twigs, branches, debris, leaves, and other objects blowing up against the side of your home. Exterior paint faces years of direct sunlight without fading and resists the development of mildew and mold. This paint is fadeless, crack-free, and chip-free – basically life-resistant. Despite its durability, it is essential to note that it can make humans and pets sick if used indoors, it is more expensive than interior paint, and its finish isn’t desirable inside. 

interior paint and outdoor paint

Should I Use Switch Interior and Exterior Paint?

Interior paint should only be used inside the home. While the pigments can adhere to exterior walls and buildings, it is not an efficient use for this paint. It does not have the proper additives or resins to withstand sunlight, inclement weather, or potential damage by the elements. Additionally, exterior paint should not be used indoors because of its harmful chemicals and off-gassing. 

How Can Paintmasters Help You?

When considering taking on a big home project like interior painting or exterior painting, it is always recommended to talk to an expert. At Paint Master Services, our team has years of experience to draw on to answer any question or concern you have going into your project. We offer a wide variety of painting services and can help you with any painting need you may have. Visit our website to get a free estimate for interior and exterior home painting, or speak to one of our team members. We can’t wait to hear from you and help you with your latest painting project! 

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