Different kinds of paints are manufactured for different purposes and come with different properties. Interior paint is made to allow cleaning and to resist staining. Exterior paint is mildew and fade-resistant. The following is a closer look at the differences between interior and exterior paint.
Paint basics: All paints contain the same basic ingredients; pigments, solvents, additives and resins.
- Solvents make paint wet and provide a vehicle for the pigment and resins to get from the can onto the surface. As the paint dries the solvent evaporates. Solvents in paint may be water, turpentine, xylene, toluene, alcohols or ketones.
- Pigments are finely ground particles that are dispensed into paint and provide colour and hiding properties (the ability to obscure a background colour).
- Resins are made of epoxy, acrylic or silicone and bind the paint to the surface. They form a continuous film on the substrate.
- Additives give paint different properties; mildew resistance, easy application, ease of cleaning, water resistance, durability, and UV resistance. Thickening agents provide viscosity, surfactants provide stability so paint won’t separate, biocides keep bacteria from growing, mildewcides discourage mildew growth and defoamers break bubbles that occur during manufacturing, shaking and application.
What’s the Difference Between Interior and Exterior Paint?
Exterior Paint is made to cover the outside of your home. Exterior paint:
- Contains extra resins (acrylic) and additional additives
- Provides protection from weather conditions (moisture, UV radiation, fungal growth, temperature fluctuations)
- Is made to combat fading
- Contains mildewcides to combat algae, mould and mildew
- Is durable to avoid chipping and flaking
- Contains flexible resins that provide protection from cracking during contraction and/or expansion
- Generally contains more volatile organic compounds than interior paint
- Can have harsh odours
- Requires sunlight to cure
- Offers few options for finishes; typically available only in flat, semi-gloss or gloss
- Is generally more expensive.
Interior Paint is made to cover the inside of your home. Interior paint:
- Contains rigid resins
- Uses organic pigments for colour, to avoid harsh chemicals
- Is meant for decoration and aesthetics
- Has additives to prevent dampness, increase washability and ease maintenance
- Can withstand abrasion
- Resists staining and scuffing and can be scrubbed
- Has low or no volatile organic compounds
- Has no harsh odours
- Comes in many finishes; matte, eggshell, satin, semi-gloss, gloss, and many types of faux-finish effects
- Is more susceptible to cracking and flaking
- Has low temperature resistance, low water resistance and fades quickly in sunlight.
- Is more affordable.
Where can I use interior paint and where can I use exterior paint?
Given their particular formulations for application on different surfaces and in different conditions, there’s no good reason to use interior paint outside or exterior paint indoors. Exterior paint should never be used indoors due to the VOCs which can outgas in small amounts for years and are hazardous to your health. Interior paint should not be applied on exterior surfaces as it will have a short lifespan due to cracking, chipping and fading.
There are marked differences between interior and exterior paint. It’s best to use the type of paint that’s intended for the surface you’re painting, interior or exterior. When in doubt as to which paint you should use, talk to a professional painter. They have the knowledge and experience to help you choose the right paint for your project.
Want help choosing the right paint for your project? Need a professional painting company? Call the Calgary residential painting experts, Cal Res Coatings at (403) 917-0579. We have experience with exterior and interior painting. We’re a residential painting contractor that strives for quality, has an eye for detail and colour, and will not rest until your job is done to your satisfaction. Request a free quote today.