You may be wondering, is there anything different between interior and exterior paints? Are they not all paints? And, can I use the same paint for interior and exterior painting?
Well, you're not the only one asking such questions. And this blog post serves to clarify things.
Notably, interior paints should not be used for exterior painting, and neither should exterior paints be used for interior painting. While interior paints are manufactured to enable cleaning and prevent staining, exterior paint is made to withstand the harsh weather conditions outside. Their purpose makes their chemical compositions different.
However, to better understand the differences between interior and exterior paints, let's get to know a thing or two about paints.
Paint chemistry
All paints, including interior and exterior, contain resins, pigments, solvents, and additives. The solvent is the solution in which everything else is immersed, and it's what gives paint its liquid or semi-liquid state. For latex paint, the solvent is water. In oil-based paints, the solvent is mineral spirits. When the paint dries up, the solvent goes into the atmosphere, and the resins, pigment, and additives remain. The pigment is the paint's color, and the resin binds it to the surface. Acrylic and epoxy are some typical examples of resins. On the other hand, additives give the paint additional properties, such as preventing mildew growth and making the dried paint washable.
Both interior and exterior paints can have the same solvents, although oil-based paint. We've seen the similarities. What then are the differences?
Differences between interior and exterior paint
The major difference between interior and exterior paint is their resins and additives. For interior paints, the resins are rigid to provide scrub resistance while also preventing it from smearing clothes.
On the other hand, exterior paints contain softer resins that help to combat mildew growth, fading, moisture, and cracking due to temperature fluctuations. While being soft, exterior paints also exhibit toughness to resist chipping, peeling, cracking, and fading due to sunlight. For these reasons, exterior paints usually contain 100% acrylic.
Additionally, additives play a major differentiating factor between interior and exterior paints. While exterior paints must contain certain environment-specific additives to boost harsh weather resistance and optimize drying time, interior paints do not have this requirement. This is why interior paint can never serve for exterior painting. On the other hand, using exterior paint for your interior would be a waste of money because the qualities are irrelevant here.
What paint should I use for my exterior?
To know the best paint to use for your exterior you have to consider several things, one of which is the surface you want to paint. Here are some of the best paints for different exterior surfaces.
Best overall: Sherwin-Williams Durable Exterior Acrylic Latex
Best for Value: Rust-Oleum Zinsser PermaWhite Exterior Semi-Gloss
Best for Porch & Patio: Kilz Interior/Exterior Enamel Porch & Patio Latex
Best for Brick: ROMABIO Bianco White Limewash
Best for Wood Siding: Sherwin-Williams Emerald Exterior Acrylic Latex.
Other things to consider when buying exterior paint include:
Durability
Volatile organic compounds (VOC) content - always go for exterior paints with low VOC or zero VOC.
Ingredients - do not go for low-quality ingredients such as talc, clay, and silica. Darker colours will also fade more quickly than bright ones.
Professional painter Newmarket, Ontario
Still don't know the right type of paint to buy or how to go about your exterior painting? We at Pro Painters Ontario are always happy to give you all the help you need. Let's make that home the haven it ought to be.