What Are the Major Differences Between Interior and Exterior Paint?

It’s easy to get confused when choosing the proper paint because there are so many options. Before learning about the chemical components of paint, most individuals choose the color and finish first. More specialty brands and products are now possible because of developments in paint chemistry. Knowing the difference between interior and exterior paints will help you complete your painting project more successfully.

Paints differ in their qualities and are designed for different uses. Interior paint is designed to be cleaned, stain-resistant, and easy to clean. Exterior paint is designed to resist fading and mildew. When beginning a painting project, it’s critical to understand the differences between the two and select the appropriate paint.

You’ll need to study a little about paint chemistry to comprehend the differences between exterior and interior paints. Continue reading to learn about the primary components of all paints.

First, let’s see some basics about paint

What You Need to Know About Paint Composition

Pigments, solvents, additives, and resins are all components of paints. Water is used as a solvent in latex paint, while mineral spirits is used in oil-based paint. The solvent is responsible for making the paint ‘wet’. The solvent will evaporate as the paint dries. The resins, pigments, and additives, which are the long-term constituents, are left. The pigment is the color that the resin binds to the surface. Epoxy, acrylic, and even silicone can be used to make resins.

Paint additives provide many features, such as preventing mildew growth, making it easier to apply, and even making it easier to clean.

The solvents and pigments are the same in both types (exterior and interior). Outside, you can use either oil-based or water-based paints, although oil-based paints are rarely used inside. The reason for this is that they have an unpleasant odor and are difficult to clean up.

How Interior and Exterior Paint Differ from Each Other 

As interior and exterior paints employ the same solvents and pigments, some pigments fade faster than others and are therefore more typically employed in interior formulations. It’s also possible that exterior paint contains more pigment. However, it is the additives and resin that make the true difference.

Weather Resistance 

Exterior paints must be able to withstand a variety of weather conditions, including temperature fluctuations, UV radiation, salty sea breezes, and more. Outdoor paint contains flexible polymers that keep paint looking excellent while the surface underneath expands and contracts to accommodate for the changing temperature conditions that paint on exterior walls will undergo. Additionally, exterior paint contains chemicals that help to prevent fading, mildew, and tannin stains.

Exterior paint has additives that allow it to endure exposure to the weather. These ingredients are not present in interior paint. Interior paint, on the other hand, has binders that help it resist abrasion.

Interior paint is manufactured with more resistant resins since it is not exposed to rain and is unlikely to be subjected to a deep freeze. These resins help to protect interior paint from scuffing and make it easier to clean.

Volatile Organic Compounds 

Some people believe that because exterior paint has to withstand more harsh conditions, it will also function better indoors. However, this is not the case! Surprisingly, exterior paint is more prone to scuffing and scratches. It will also produce additional VOCs (volatile organic compounds) as it cures and even after it is finished curing, making it unfit for indoor usage. On humid days, mildewides and fungicides in exterior paint can emit an odor and possibly cause allergic reactions.

Concerns regarding the influence of volatile organic compounds (VOCs) on indoor air quality prompted the introduction of low VOC interior paint several years ago. There are several low VOC and even no VOC interior paint alternatives available these days. While some paint manufacturers are now offering low VOC exterior paint, the VOC levels in most exterior paints are another reason they aren’t suitable for inside use.

Alkyd Vs. Acrylic Resins 

The most frequent resins in paints were alkyds derived from plants until latex paint was discovered in the 1940s. Alkyds are huge, heavy molecules that are nearly inert yet have enough reactivity to react with oxygen and cross-link with one another to form a hard film. 

Latex paint, on the other hand, is made up of acrylic plastic and natural or synthetic latex rubber. Although acrylic is a rigid material, it is made more flexible by the addition of latex. Acrylic latex is soluble in water, whereas alkyds are soluble in turpentine and mineral spirits (both petroleum products).

Exterior Painting Vs. Interior Painting 

Interior painting differs from exterior painting in more than just choosing the proper product. Because separate tools and application methods are required for each procedure, each one is distinct.

Pressure washing the building, removing rust, and putting a rust-inhibitive primer may be part of the surface preparation process for exterior. Before proceeding to the painting stage, a skilled external painter ensures that the surface is dry and that the weather conditions are suitable.

Interior surfaces, of course, require softer cleaning procedures. The interior painter selects the appropriate primer for the wall’s condition as well as the paint he intends to use. It’s also crucial to pick the correct tools. Interior painting, for example, may necessitate a soft brush for trim yet a firm brush for cutting walls.

Can’t Make Up Your Mind About Which Paint to Use?

Consult with the experts at Express Paint for assistance in picking which paint to use for your next interior house painting or exterior house painting project. We have a lot of happy customers who use our services. Express Paint is a family-owned and operated company that specializes in painting projects. 

For a free quote on your next painting project, please contact us.