Can the interior paint be applied to the exterior? here is the answer (2023)

Are you planning to use leftover paint from the living room or basement for some patio furniture or to repaint an exterior wall or door? Want to know if you can use interior paint on the outside? While the short answer is yes, it's not recommended.

Interior paint is not designed to withstand rain, snow, wind, UV rays, mildew or extreme temperatures. It has less binding pigments and resins than house paints and the surface is very porous. As a result, the paint will fade faster, become dusty or chalky, crack and peel.

In this article, we'll look at interior paint, what it's made of, and why it's best for indoor use. We'll also discuss what to do if you're using it outside. By the end of the article, you'll have a better understanding of what interior paint is and why it's best for interior use.

What is interior painting?

Interior paints are specially formulated for indoor use. They are designed to adhere to a variety of surfaces, reflect or absorb light, and resist abrasion and wear from daily contact and cleaning. They also don't have to withstand the expansion and contraction of the freeze-thaw cycle or nature's harshest elements.

The paint consists of four parts: the base or liquid, the additives, the pigments and the binders. Binders, pigments and additives distinguish the inner paint from the outer paint and are not interchangeable. Interior inks are designed to contain less volatile organic compounds (VOCs) to minimize health risks from off-gassing. VOCs are the solvent that helps keep the liquid from hardening; They evaporate when the paint dries.

Pool

Interior paints can be water-based, including latex and acrylic paints, or oil-based, such as B. alkyd paints. Water and oil bases offer different adhesive properties and uses. Both are available in different gloss levels, from high gloss, semi-gloss to matte. If you're not sure whether something was painted with oil paint or water-based paint, wipe it off with a cloth dipped in denatured alcohol. If it doesn't color, it's probably oil-based; If yes, is it water based?

You can paint over oil paints with water-based or latex paints after applying an oil-based primer or stain-resistant sealer. Oil-based paints can be used over water-based paints after drying; It may be necessary to gently sand shiny surfaces with sandpaper.

water based paints

Water-based or latex paints consist of pigments and binders mixed with water as a vehicle. They dry faster because the water evaporates and the color stays. Latex painted surfaces are easier to clean and retain color better than oil-based alternatives. The ink typically has fewer VOCs, making it more environmentally friendly than oil-based inks.

Once dry, interior latex paints provide flexible, durable color and are ideal for painting ceilings and walls. Many prefer water-based paints for easy cleaning of brushes, tools and spills with soap and water.

oil based paints

Oil-based paints contain natural oils, such as linseed, tung, or soy, or synthetic alkyds. They contain pigment, oleoresin binder and a thinner solvent. When applied to a surface, the thinner will evaporate, leaving behind resin and pigment to form a hard, durable coating.

Oil-based paints generally produce more VOCs, making them less environmentally friendly and making surfaces more difficult to clean. Oil-based paints work well on doors, trim, and baseboards, which need a longer-lasting paint than most walls due to exposure to vacuums, furniture, and dirty hands.

Inks take longer to dry, but form a strong, durable, hard film. Cleaning is more difficult and requires thinner, white spirit, or mineral spirits to remove brushes, tools, and spills.

Liquids or solvents and additives or fillers

Water in latex paints and mineral spirits in oil paints transport and spread the paint from pigments and binders onto surfaces and then evaporate. Colors have different additives depending on the application.

• Fillers such as clay, talc, lime or barite help to thicken the paint film.
• Adhesion additives improve the ability of paints to "stick" to various surfaces.
• Glaze is added to paint to make it harder, more durable, and less porous when dry.
• Antimicrobial conditioners or additives improve flow and reduce brush drag, resist mildew, and improve fade ability.
• Structural additives like fine sand to make stairs less slippery.
• Glitter to enhance reflective properties.
• Fragrances are also added to improve the smell of the paint.

pigments

Pigments provide the ink's color and can be organic or inorganic. Pigment type can also determine color durability, which affects how often walls need to be repainted or repainted. Organic pigments are of plant or animal origin and are naturally transparent.

Traditionally, they are not as durable as inorganic pigments, but modern chemistry is changing that. Inorganic pigments are solid mineral colors that occur naturally but are modified to make inks.

Inorganic pigments are long-lived and have been found in cave paintings dating back 30,000 years. All white pigments come from inorganic sources, titanium dioxide being the most common. Organic pigments mix, mix and disperse in the base and have better transparency than finely ground inorganic particles mixed and suspended in the base. A greater number of inorganic particles creates firmer content, resulting in deep, rich colors.

chainer

Binders hold pigments together to create a permanent film on a surface. Plastic-like polymers provide better adhesion to various surfaces and resistance to abrasion and household detergents. In latex paint, the binders must be 100% acrylic, not a mixture. Oil paints often contain drying oils such as tung oil, linseed oil or modified oils.

Can the interior paint be applied to the exterior?

There are many reasons for wanting to use interior paint on the exterior. It might be less expensive, you want to use an extra color, or you like the color are just a few reasons I've heard. While you can use interior paint on the outside, you shouldn't.

Interior paints have a different formulation than exterior paints. Not designed to withstand freeze and thaw, rain, snow, mold and mildew, they fade, fade and crack more easily. Interior paints are more porous, lack resin to adhere to exterior surfaces, and are more likely to crack and peel.

If you decide to use interior paint outside, then it must be sealed with one or two layers of exterior clear sealant. Depending on exposure to the elements, this may increase tack time but does not necessarily prevent discoloration and the sealant may yellow.

Using interior paint with a sealer increases the amount of work and makes a more expensive exterior paint a less expensive finish. Using indoor paint outdoors will also void the warranty.

Painting the inside surface of an entryway with interior paint is good because the surface is protected from the weather. The surface must be properly prepared, especially if it is a metal door. You can use the same color on the outside of the door if it is protected by a storm or glass door; Otherwise, it may fade, crack and chip.

Interior paint can be used on interior concrete walls or panels with a lot of prep work: crack filler, TSP to clean the surface, a sealer, a masonry primer, and several coats of paint. However, using interior paint on exterior concrete requires an extra coat or two of quality exterior finish over the interior paint. Exposure to the sun and other elements causes interior paints to fade and wear faster than exterior paints.

Some people wonder about using interior paint as an exterior primer. Whether it's to minimize costs or any other reason, you can use it as a base. It needs to be lightly roughened with sandpaper to improve adhesion and then coated with a quality exterior paint on the same base.

Unfortunately, the surface may need to be repainted every year or two, depending on the quality of the adhesive and extreme weather conditions. Modern interior paints are formulated for indoor use, not outdoor use.

What if you accidentally used interior paint on the outside?

Whether you picked the wrong can of paint or simply didn't realize there was a difference until it was too late, accidents happen. Using interior paint outside isn't the end of the world. It just means you'll probably be repainting the surface in two to five years instead of ten to fifteen years.

Interior paints are formulated for the protected surfaces within a building, so they don't withstand the rigors of nature. It fades faster and contains no additives to protect against extreme temperatures, UV rays or mildew. You can paint it exterior paint now or wait and do it in a year or two.

If you are almost done with the work, you better finish it. If you're just starting out, you can switch to exterior paint and paint over it. Some suggest painting the interior paint with an expensive sealant and treating it as a lesson learned. Alternatively, you could save money and buy a quality exterior paint in the same color and primer instead of a more expensive sealer and just apply another coat.

Can I paint over exterior paint with interior paint?

Inner color and outer color are not the same. Modern technology and chemistry have improved products for indoor or outdoor use. If you want to apply an inner color over an outer color, the quick answer is yes; The long answer is... why?

Applying interior paint to an exterior paint requires surface prep work and the use of a primer if it is a water-based paint over an oil-based paint. When paint is exposed to the elements, it's important to note that it will not withstand changes in temperature, humidity, UV rays, mildew, or elements like exterior paint.

Using interior paint over exterior paint can save you some money to get started. It won't last that long, so apply another coat first and eat up all the savings. The labor factor also increases. If an exterior wall has become an interior wall as a result of a conversion or extension, you can confidently paint exterior paint with interior paint. However, interior painting is not recommended for exterior use and will generally void any warranties.

Conclusion

Interior paint is formulated for indoor use and is best suited for that use. The paint can be used outdoors, but it doesn't weather well and you'll have to repaint sooner than planned.

I hope you have a better understanding of indoor paint, why it's called indoor paint, and what happens when it's used outdoors.

If you find this article helpful or interesting, please share it. As always, your comments and suggestions are welcome.