Paints are basically developed using the same basic ingredients such as resins, pigments, solvents, and additives. However, manufacturers tweak the paint properties based on the surfaces and environment that the paint will be used on. Interior and exterior home environments in San Diego are quite different, and so the paint formulations need to be adjusted to match the difference in the environment.
Interior and exterior paints have similar solvents and pigments, but the exterior paints might contain more pigment. However, the main difference lies in the resins and additives, and this needs some basic paint chemistry to understand.
Paint Chemistry Basics
A can of paint is made of a mix of ingredients that work together to form a hard protective coating for metal, wood, drywall, concrete, and other surfaces. The chemicals in the paint are often suspended in a solvent, which evaporates once the paint has been applied.
Latex paints have water as their solvent while oil-based paints use mineral spirits. Once the solvent dries, you are left with the resins, pigments, and additives, which are the lasting ingredients. The polymers usually form the surface, the binders prevent it from separating and the pigments provide the colors that you actually see.
Paints may also include additives that help to improve weather resistance, regulate drying, keep the pigments distributed uniformly in the solution and control mold and mildew. The resins bind the color pigments to the surface, and this can be either acrylic, silicon or epoxy.
Unlike two decades ago when professional painting contractors in San Diego considered interior and exterior paint interchangeably, the difference between interior and exterior paints have become very important today. As paint formulations improve, exterior paints are today generally formulated to withstand weather conditions without easily fading or peeling.
So, what is the difference?
Exterior paint is generally exposed to varying weather conditions and all sorts of environmental elements. The paint is required to provide protection against UV radiation, organic growth, and dampness during precipitation. They’re therefore typically UV resistant and come with additives to combat mold and mildew. If you’re in a mildew prevalent zone, you might want to use formulations that have fungicides.
The resins used in the exterior paint are generally softer and more flexible to avoid cracking during contraction and expansion. Exterior paint should also be able to resist peeling and cracking, and withstand extended exposure to moisture. If you have a termite infestation, you might want to use paints that have pesticide additives once you’ve eradicated the pesticides. Exterior paint is also able to absorb small amounts of water and release it without cracking or blubbing.
Interior paints are primarily developed for aesthetic and decoration purposes while protecting against dampness and being washable. Interior paint is generally designed to withstand abrasion, but it’s more delicate than exterior paint. Other than being resistant to physical damage, interior paint also needs to be stain resistant.
The resins used for interior paint can be firmer because the paint does not have to deal with frequent contraction and expansion. Interior paints don’t have to be UV or fade resistant since they are not directly exposed to sunlight. Similarly, they typically don’t have fungicide or pesticide additives. Lastly, interior paints need to have zero VOC (Volatile organic compounds) in order to preserve the air quality in your home.
The Bottom Line
As you can see, the interior and exterior paints look similar in many aspects but have fundamental differences that make them suitable for their respective environments. If you’re hiring a San Diego professional painting contractor like Peek Brothers Painting, the hassle of choosing the right paint for your painting projects will be fully taken care of. Simply give us a call and let us have a chat about your project.
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