Since different paints are created for various purposes, they all have unique qualities. Mildew and fading are issues that exterior paint is designed to combat. On the other hand, interior paint is designed to be washable and stain-resistant.
To distinguish between two types of paint, one needs to learn about the chemistry of each type of paint to distinguish between the two. Let’s examine each sort more closely to determine how they specifically differ from one another. However, it’s crucial to understand how paint works and how it’s created before we get into the distinctions between exterior and interior paints. The same fundamental components are used to develop all paints. These consist of pigments, additives, solvents, and resins.
Oil or water serves as the paint’s primary base, which is referred to as a solvent. Oil-based paints are typically utilized for external paints rather than interior paints. Both interior and exterior paints can be made with water-based paints.
Color is transmitted to paint by pigments. Special additives can change the physical characteristics of your paint, such as its durability or resistance to UV rays and water. The solvent or base in the paint will start to evaporate when you apply it to a surface. When it does, all left is the pigments and additives; the resins have adhered to the surface.
Acrylic, silicone, and epoxy are all examples of resins. Exterior paint typically employs harsher resins with better adherence because it must adhere through more choppy circumstances.
Let us learn more about these two kinds of paints.
Features of Exterior Paint
- Exterior paint is exposed to a variety of weather conditions. It must therefore offer defense against moisture from rain and snow and UV radiation brought on by sunlight. It must also protect against microbial development.
- These coatings are designed to fend off mildew and fading. They must be able to withstand extremely high temperatures as well as the UV rays indicated above.
- The resins used in exterior paints are soft, as was already indicated. They are also incredibly adaptable. As a result, they resist cracking, whether under contraction or expansion, and can withstand the negative impacts of moisture and temperature variations.
- This form of paint may be applied to numerous substrates by altering the sheen. The exterior of a house absorbs a little water when it rains. Flat paint won’t bubble; instead, it’ll let the water drain off.
- Exterior paint shouldn’t be used indoors because it releases more volatile organic chemicals. Additionally, it needs sunlight to cure.
Features of Interior Paint
- Interior paint is applied for aesthetic purposes inside a building or house etc. Interior paint also has the benefits of being washable, easy to maintain, and moisture prevention.
- Abrasion resistance is an essential feature of interior paint formulations. It is made to be more sensitive than exterior paint because it is applied in the space people most live in or frequently use.
- This paint can be scrubbed and is stain-resistant. It has no fading resistance because it is not exposed to sunshine. Additionally, sunlight is not required for a cure.
- It can also be cleaned. Removing brush and roller markings and stains that children and pets have left behind is simple.
- The paint for interiors must contain few or no volatile organic chemicals. This lowers health hazards and is essential to maintaining indoor air quality.
Interior vs. Exterior Paint: What’s the Difference?
After reviewing the fundamentals, let’s examine how these two major paint types differ. The only similarity is that both will alter the color of any surface you put them on.
Binding Resins’ Type
The primary distinction between these two varieties is the resin choice. As we have explained, the resin holds the pigment to the surface you’re painting on.
The strength of the paint’s adhesion to a surface will depend on the binding resin. Acrylic is the binding resin in exterior paints because it has a strong bond and will provide the most extraordinary durability. On the other hand, interior paints stick to epoxy and silicone because acrylic might have unpleasant scents.
As discussed, the pigments in your paint give it color. Interior paints use organic dyes to prevent introducing additional chemicals to the mix. These are safe to breathe and have no unpleasant scents. The non-organic pigments used in exterior paints can help increase the pungent odors and fumes. Still, they fade slowly because exterior paints need durability more than they need to keep out harsh chemicals.
Interior paints don’t have as many additives because they don’t have to cope with as many potentially hazardous circumstances. However, exterior paints must withstand weather, debris, temperatures, and more. Additional additives that can assist the paint in tolerating temperature changes, resisting fading, and even avoiding breaking are utilized to help with this. To help stop the growth of mildew, mold, and algae, mildecides are also added to exterior paints.
Interior paints are not intended to withstand abrasive or unpredictable weather. This causes them to have low-temperature resistance, low water resistance, and fast photochemical fading. However, exterior paints have higher weather resistance because they are designed to survive all of them.
Exterior paint is designed to last years of weather abuse. It is also built to be resilient enough to withstand impacts like flying insects or twigs blown against your home by the wind. It is, therefore, significantly more durable than interior paint. However, interior paint is challenging and can endure the occasional scrubbing and cleaning.
Protection against physical damage
Your interior paint may probably chip off if it receives a direct blow, showing the old paint or bare wall underneath. It is significantly more challenging to chip exterior paint because of how strongly the resins bind the pigment to the surface.
Quantity of VOCs
Volatile organic compounds, or VOCs, give off vapors that can be dangerous to breathe. Fortunately, interior paints contain very little or no VOCs at all. Exterior paints, however, are not the same. Exterior paints are frequently packed with VOCs that will release into the open air outside because they aren’t meant to be used inside. But if this occurs indoors, there may be a health concern.
Paints for the inside and outside have good adherence. On the other hand, interior paints cannot match the claim that exterior paints adhere well enough to endure all types of bad weather. Exterior paints typically adhere better and remain longer.
Time To Dry
Water-based paints often dry faster than oil-based paints. Interior paints without consistent ventilation will take longer to dry than exterior paints in the open air. Finally, heat will hasten the drying process of the paint. When all these factors are considered, exterior paint typically dries more quickly, especially water-based.
Resistance to Fade
Sunlight is one of the external elements that your paint must constantly fight against. Most days during the year, the sun will beat on it for 12 hours or longer. Thankfully, exterior paint additives are designed to withstand this fading and provide UV protection. Interior paint, however, is not intended to tolerate direct sunshine. Since interior paint lacks additional ingredients to delay fading, the organic pigments will deteriorate quickly.
Paint for the outside is designed to endure various temperatures. It must endure every temperature between freezing in the winter and sweltering in the summer. However, interior paint is only meant to be used in the typical range of temperatures seen in most homes, between 60 and 90 degrees Fahrenheit.
Resistance to Moisture
Since rainstorms, thunderstorms, simple showers, and other weather events are somewhat regular in most places, exterior paint must be resistant to them all. Only sporadic washings are required for interior paint. Naturally, this dramatically increases the water resistance of external paint.
Resistance to Scuffing and Scratches
Both interior and exterior paint have a respectable level of scratch and scuff resistance. However, exterior paint’s durability ultimately prevails. Without suffering any damage, it can withstand significantly severe scuffing.
Interior paint is often free of hazardous chemicals, harsh additives, and hazardous VOCs because it is intended for indoor use. However, exterior paint is exempt from these rules. As a result, many exterior paints contain these compounds and chemicals. Exterior paints may become more robust and weather-resistant, but they may also emit gases as they dry. After a few days, most of the gas is released, although it will continue to outgas for several years.
There is a noticeable price difference between these two types of paint. Exterior paint typically costs more since it has more chemicals and additives and lasts longer. Although interior paint generally costs less, it doesn’t provide the same level of protection and durability.
Where is one preferable to the other?
- The different resins in exterior paints may induce outgassing. Typically, this procedure takes up to two days. However, outgassing can still occur for years on much smaller levels. For this reason, exterior paint should never be applied indoors.
- Use a flat sheen exterior paint on masonry and stucco. This enables these surfaces to breathe, allowing the moisture to evaporate through the paint. It’s crucial for brick walls in particular.
- Interior paints are significantly more delicate, as was already indicated. Additionally, they do not outgas the same way, making it safe to use them indoors. However, good ventilation is still necessary during painting.
Although it can appear negligible at first glance, where you apply each type of paint can have genuine repercussions. You risk having strong chemical odors flooding your house if exterior paint is applied to inside surfaces. If you paint the exterior of your home with interior paint, it will probably crack, chip, and fade away very quickly.
Whether painting an indoor or outdoor surface, it is essential to use paint designed for that surface. Of course, you could always choose an indoor/outdoor paint to eliminate all uncertainty. These “universal” paints have a lot of uses, but they also have drawbacks. Consult a professional painter if you need clarification on the kind of paint you ought to use.
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