The Difference Between 2k And 1k Clear Coat

There are quite a few posts and videos on how to fix peeling clear coat. Many of this information is wrong as they suggest any old spray can clear. Whenever you want to clear something that is exposed to the outdoors, you need to know the difference between 2K and 1K clear coats.

Difference Between 2k And 1k Clear

When it comes to applying a clear coat, it is important to know what it will be exposed to. If painting interior parts or anything that isn’t exposed to harsh conditions, a 1K clear can be a solution. However, if you are painting something that is exposed to sunlight or weather, then you may need a 2K.

There are three basic types of automotive paints. Lacquer, Enamel and Urethane. Only one of these paints cannot be 2K, which is lacquer. Enamel can be both 1K and 2K and urethane is only 2K.

What Are 1K Coatings

Any paint that is a single component, that only requires air to dry is a 1K. The majority of aerosol paints are 1K. You can also include house paints, or any type of coating that are brushed on or rolled on. Some automotive chassis paints are also 1K. These types of chassis paints are ready to spray right out of the can. They are air dry coatings.

Up until almost 10 years ago, all aerosol paints were 1K, air dry only. You mostly had lacquer and enamel paints in aerosol. Both come with solvents in the paints that is what cause them to dry by air. Lacquer paints were most common with aerosols in the beginning. It dried fast and was pretty durable. Although, the lacquer solvent would eat plastics and react with other paints. Enamels were introduced and was less aggressive, although would take longer to dry.

In the automotive auto body industry, they make 1K coating for a variety of applications. There is an Acrylic Trim and Jam clear. Many automotive painters will use it to spray the door jam and under the trunk areas. Waterborne coatings were introduced back in the 90’s. It too is a 1K application. It only requires air for it to dry.

What Are 2K Coatings

Any paint that has two components that require a chemical reaction for the paint to dry is 2K. When a paint requires an additive to catalyze or some know as harden the paint. This is a 2K type of coating. 2K coatings are far more durable than and resistant to weather and other chemicals. 1K coatings can easily be damaged with gasoline, oil, or anything with lacquer in it. 2K finishes can resist lacquers or other solvents. They are also very resilient to sunlight and weather.  

2K coatings are more than just clear coats. You can get paints that are called single stage that require a catalyst. You will find that epoxy paints used for industrial or marine use are also known as 2K. Today, you can purchase a 2K clear coat in aerosol. The can has a protected chamber inside that contains the activator. There is a button on the bottom that when pressed, releases the catalyst into the clear.

So, this is the real difference between 2K and 1K clear coat. One clear is air dry and the other dries by chemical reaction. Thanks to these 2K clear aerosols, it allows any Do-It-Yourselfer to do a low-cost clear coat repair.

Understanding What Base Coat Clear Coat Is

This should be a post on its own, but I wanted to touch base on this just a little. Since many people don’t quite know the difference between 2K and 1K clear coats are and their applications. Especially when it comes to automotive paint. I wanted to go over this real quick.

Most people at least know the term “base coat, clear coat” when it comes to their cars. But understand, not just any clear will work over the base coat. A lacquer 1K clear being sprayed over a base coat can cause a serious chemical reaction. You also need to know, that a base coat has to have clear over it. It is not a paint that can withstand weather or sunlight. It requires the clear to protect it.

As mentioned above, a 1K clear doesn’t have the correct elements in it to withstand weather and sunlight. So, never use a 1K clear over a base coat. One it will not bond with the base coat correctly. Two, it will not last any time at all. And last, there is a big chance it can react with the base coat and lift it off.

Make not, the difference between 2K and 1K clear coats in base coat applications are. You never use a 1K clear to go over a base coat on a paint job. Always use a 2K clear, no matter if it is from a spray gun or aerosol can.

The Difference Between 2K And 1K Clear Coat Conclusion

You can use a 1K clear for interior parts, crafts or home uses. It can be used anywhere that it isn’t exposed to greases and oils. Heat from the direct sunlight or from day-to-day weather conditions. UVs from the sun will bake a 1K clear away to nothing.

You would never want to use a 1K clear in or around the engine compartment of a vehicle. The oils and vapors will lift the clear like paint remover.

2K clears are designed to resist UVs from the sun. The catalyzation process, pretty much makes the coating like plastic. This gives it the ability to withstand weather and exposure to chemicals, oils and solvents. These 2K clears usually cure anywhere from 4 to 12 hours, depending on the quality of the brand. Once cured, they are “good-to-go.”

I hope this helped explain the difference between 2k and 1K clear coats. If not, just contact me and I will do my best to help you..


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