What is the Difference between Exterior & Interior Paints?

To reach the best outcomes while painting your space, it is crucial to understand the difference between interior and exterior paints. Each type of paint is formulated with specific ingredients and properties to suit different environments, making it uniquely designed for either outside or inside applications. This guide will explore the key distinctions between exterior and interior paints, discussing their compositions and ideal uses so you can make informed choices for your painting projects.

The Purpose of Exterior & Interior Painting

Exterior painting protects and aesthetically enhances a building’s exterior using paint specifically formulated to withstand harsh outdoor conditions like weather, sunlight, and moisture. While Interior painting aims to beautify and protect a building’s interior with paint designed for a controlled indoor environment, prioritising ease of cleaning and maintaining a desired aesthetic appearance.

The Basic Components of Paint

Paint combines science and artistry, merging essential elements to produce lasting, attractive finishes. From the vivid colours of interior paints to the strong protection of exterior paints, the fundamental components stay consistent:

Pigments for Colour

• Give paint its colour and aesthetic properties.
• Can be organic or inorganic.
• Examples include titanium dioxide, Hansa yellow, and phthalo blue.

Resins for Adhesion

• Keep pigments combined and make the film of paint.
• Also known as resins or latex.
• Responsible for the paint’s proper adhesion to the surface.

Solvents to Carry the Mixture

• Mix of components that make the paint ready to be applied.
• Can be water or oil,
• Also known as thinners.
• Affect the paint’s drying time and spreadability.

Additives for Enhanced Properties

Offer definite properties to the paint, like:

• Mildew Resistance
• Glossiness
• Opacity

What Are Exterior Paints?

Exterior paint is a type of paint designed to withstand the elements and protect the building’s exterior components. It is formulated to resist the impact of rain, wind, UV rays, and extreme temperatures. Exterior paints are made of pigments, resins, solvents, and additives and are designed to be durable and weather-resistant.

Properties of Exterior Paints

Durability

Exterior paints are specially designed to compete with tough outdoor conditions. They must resist the damaging effects of rain, intense sunlight, temperature fluctuations, and humidity, which can lead to peeling, fading, and other forms of deterioration.

Weather Resistance

These paints are designed to effectively withstand UV degradation and moisture damage, ensuring that the colours remain vibrant and the surface remains intact over time.

Mildew and Mould Resistance

Certain types of exterior paints, particularly those made from latex and acrylic, incorporate properties that resist the growth of mould and mildew. This is especially crucial in areas with high humidity or damp conditions to preserve both the appearance and hygiene of the painted surfaces.

Finish

Exterior paints are available in various finishes, including flat and satin. Flat finishes excel at hiding surface flaws and delivering a sleek look; however, they might need extra attention when cleaning. On the other hand, Satin finishes are easier to clean and give a subtle sheen, enhancing the aesthetic appeal of exteriors.

What Are The Interior Paints?

Interior paints come in various types and finishes, including matt, satin, eggshell, gloss, and silk. The type of paint you choose depends on the look and feel you want to achieve and the area you’re painting. Interior paints are made up of pigments, binders, solvents, and additives. These ingredients combine to give the paint its colour, opacity, and other properties.

Properties of Interior Paints

Interior paint has properties that make it suitable for use in the interior of buildings, such as rooms, kitchens, offices, and bathrooms. These properties include:

Washability: Interior paint is designed to be easy to clean so you can remove marks and stains left by kids, pets, and you.

Stain Resistance: This paint is designed to resist stains and withstand scrubbing.

Abrasion Resistance: Interior paint is designed to withstand abrasion.

Low Volatile Organic Compounds (VOCs): Interior paint has low or zero VOCs, which reduces health risks and improves air quality.

Good Coverage: This paint has good hiding ability and coverage.

Easy TouchUp: Interior paint is easy to touch up.

Dampness Prevention: It can help prevent dampness.

Aesthetic: It is used to enhance aesthetics and for decorative purposes.

Safe for Human Health: It does not contain harmful substances that pose risks to human health.

Key Differences Between Exterior & Interior Paints

Composition

Exterior Paint

Uses softer resins and additives to make it flexible and resistant to UV light, allowing it to withstand tough outdoor conditions.

Interior Paint

Made with strong resins for durability against high traffic wear and tear and frequent indoor cleaning.

Additives

Exterior Paint

Has additives that improve resistance to cracking, fading, and mould growth, resulting in a longer-lasting finish outdoors.

Interior Paint

Contains low VOCs to improve indoor air quality, making it safer for homes.

Intended Use

Exterior Paint

Designed to protect outdoor surfaces from rain, sun, wind, and other weather elements.

Interior Paint

Made for indoor surfaces to handle regular use and allow easy cleaning while maintaining its look for longer.

Application

Exterior Paint

It should be applied in dry weather for an even finish.

Interior Paint

Roller and brush techniques should be used for a smooth and appealing finish.

Health

Exterior Paint

Has higher VOC levels but increases durability and drying speed, suitable for outdoors.

Interior Paint

Low VOC levels reduce health risks from harmful chemicals, promoting a healthier home environment.

Safety

Exterior Paints

Using exterior paint inside can create health risks because of the high VOC levels in enclosed spaces.

Interior Paints

Using interior paint outside can cause problems like cracks and peeling due to weather exposure.

Can Interior Paint be Used for Exterior Painting?

While technically possible, interior paint can be used for exterior painting. However, it is highly discouraged since it is not built to endure outdoor conditions like:

• Rain
• Sun
• Wind
• Harsh Climate Changes

This leads to rapid deterioration, peeling, cracking, and colour fading, making it a poor choice for long-term exterior use; always opt for dedicated exterior paint when painting outside surfaces.

Can Exterior Paint Be Used For Interior Surfaces?

No, using exterior paint for interior painting doesn’t make sense. Exterior paint is intended for outdoor environments and may be hazardous if used indoors. Here are some reasons why exterior paints are not suitable for interior painting:

• Health Risks
• Poor Performance
• Not Scrubbable
• Not Waterproof