Both the single-coat and the two-coat system allow for painting an object to protect it and beautify it by giving it color and a given level of gloss. However, stemming from this similarity, there are differences between one painting system and another. These differences attend to different aspects of painting that affect the quality obtained, the durability of the coating or its environmental impact, among other things. Please find the most relevant ones in the following table:
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1st difference ' Definition:
The single-coat system provides color and shine using a single product, while the two-coat system requires two products, a base coat for the color and a clear coat to provide the shine
2nd difference ' Paint technology:
The second difference refers to the composition of the base. In the case of the single-coat system, it is a solvent base coating. On the other hand, the two-coat base can be either water or solvent-based, and in the case of clear coats, it is always solvent-based.
3rd difference ' Harmful and polluting effect:
In the bilayer system, there are systems on the market that are not so respectful towards the environment, while there are others that are more compliant. With regard to environmental preservation, the water-based two-coat systems comply with the strictest regulations regarding environmental protection. Generally, in order to comply with restrictive legislation on environmental issues, we would use low-VOC clear coats. Single-coat systems.
4th difference ' Environmental resistance of the paint:
Single-coat finishes are less environmentally resistant than two-coat systems, which are designed to offer increased durability. This means that over time and depending on weather conditions, they could degrade, losing brightness and showiness.
5th difference ' Colorimetric limitations:
Single-coat finishes used in the automotive sector are only available in plain colors, which significantly narrows down the color palette and customization options. In the two-coat system, the colorimetric variety is very extensive. There are all kinds of plain colors, metallic, pearlescent and with special effects. Thanks to this, car owners enjoy many more options when it comes to customizing their vehicles.
6th difference ' Main applications:
Due to their limitations, the current applications of single-coat bases are mainly focused on commercial vehicles and new cars, where the aesthetic aspect is not so important for the client (white, black, plain red, etc.). On the other hand, the two-coat system is used in finishes where the aesthetics sought cannot be achieved using single-coat finishes, such as metallic, pearlescent or candy colors.
7th difference ' Preparation of primers:
Since they are coatings with a certain filling power, primer preparation in single-coat systems is less laborious than in two-coat topcoats. Generally, they cover sanding scratches up to P-400 dry. Normally, due to the particles and special finishes, in the two-coat system, the preparation is a little more rigorous to avoid scratches that we would not see in single-coat finishes. It is very common to use blending techniques in this type of topcoat. Thus, we will also carry out a specific preparation for this type of application.
8th difference ' Application:
As a general rule, the application of single-coat colors is carried out in two coats. Both are applied using the same technique, and the only precaution to be taken is to avoid overloading the first one in order to cover the patch, since the coverage is achieved with the second coat. In two-coat colors, different applications may be identified
9th difference ' Color adjustment:
The adjustment of the single-coat colors is easier, since they do not include any type of effect. Matching the color of a two-coat base is more complex, especially when working with metallic, pearlescent and special effect colors. With two-coat matt topcoats, the adjustment of this type of clear coats is also a problem, since there are no specific tools to determine the level of gloss.
10th difference ' Color:
The difference in tonality in these colors after refinishing is less frequent, due to the fact that there is less variety of colors and they do not integrate effects. The greater ease of color adjustment that characterizes them also reduces this risk. The wide range of colors and effects available means that there is a greater risk of color changes and the appearance of phenomena such as the flop effect. Therefore, it is essential to have specific tools that facilitate the color identification process.
11th difference ' Correction of defects
In single-coat systems, we will usually use a sanding and polishing process that will allow for correcting the issue or defect. In the case of the two-coat system, the existing sanding margin corresponds only to the clear coat, so that if it is sanded excessively, rims appear on the base coat and repainting becomes necessary.
12th difference ' Cost
The single-coat system has a lower cost since only one process and therefore one product is needed. In the two-coat system, the cost is higher given that a two-coat base and a clear coat need to be used.
It's freezing and raining out, and your kids want to go outside to play. Would you let them go out there without coats?
I wouldn't either.
Consider this situation: it's the same weather, but instead of your kids, it's an expensive piece of fabricated metal. That metal spends a great deal of time outside. How long before it starts corroding?
Both situations need layer protection. It's a simple solution for your kids, make them wear their coat. What's the answer for the fabricated part?
If you are looking for more details, kindly visit Double coating line.
Note: This article is the first of a series exploring the e-coating process.
Part 1: Two-Coat Systems Using E-Coating
Part 2: Is a Third Coat Necessary?
Part 3: Testing Topcoat Strength
What is a two-coat system? The simple definition of a two-coat system is a method of applying two coatings to the same component. The two-coat completely covers the material's surface improving corrosion resistance.
Although there are many ways of applying finish to a component, only one provides the best material coverage: e-coatings.
Electrophoretic deposition (e-coating/electric coating) is like electroplating. The electroplating process uses electric current reducing dissolved metal cations, forming a thin, coherent metal coating.
E-coating occurs while dipping the parts in a bath of epoxy, water-based solutions, or paint while adding an electric current.
The current causes a reaction within the bath, depositing floating particles on the component. The amount of time using the electric current determines the coating thickness. After coating the part, it's moved to a curing oven to finish the process.
There are many similarities between powder coating and e-coating. Both methods use electric current to bond coatings to a substrate. E coatings are usually better options than powder coating because the submersion coats hard-to-reach areas of the part.
Controlling the thickness of the coating becomes easier to manage when e-coating, too. This process applies a consistent and repeatable coating over most finishing methods.
Two of the most common e-coating processes are anionic and cationic.
The anionic process applies a positive charge on the component, while the fluid in the bath is negatively charged. Anionic methods are standard in the general metal industry, need color control, have easy operation, and are cheaper.
If using a component in a non-corrosive environment, the odds are the anionic process coated the part.
The cationic process provides a surface more resistant to corrosion and reverses the anionic process. The component is negatively charged, while the fluid is positively charged. The chemistry involved in the cationic process is based on acrylics or epoxies. If corrosion protection is critical, use epoxy chemistries. If applications need color control or durability, then acrylic systems are typically used.
With a history dating back to the s, e-coating provided a coating inside steel food containers. Around 30 years later, many industrial applications started using the e-coating system.
Ford Motor Company was at the forefront of e-coating technology. In the early s, Ford scientists created an anodic process for e-coating an assembled auto giving anti-corrosion protection. A few years later, domestic appliances and architectural aluminum successfully used the e-coating system.
In the mid-s, Ford advanced e-coat technology by replacing anodic with cathodic processes where a continual DC circuit in the bath applies the e-coatings.
Since then, recent advancements in e-coating technology led to improved edge protection, low-voltage organic compounds, and more protection from UV light. E-coating is now used when making electrical components and heavy equipment needing corrosion protection.
There are four main parts to the e-coating process including:
The debate between powder coating versus e-coating is an entirely different article. Instead of highlighting that discussion, we're only exploring the advantages of using the e-coat system.
Some of the significant advantages of using e-coating include:
I was one of those parents who believed touching a hot lightbulb is one of life's best lessons. I warned my kids often to stay away, but being curious kids, they kept pushing the envelope, learning as much as possible.
They ignored my fantastic advice, and several ice cubes melted against an injured, tiny finger.
Here's where I'm going with this. You reading all the advantages e-coating provides results in forgetting about them in a short amount of time. We explore the different testing methods for the strength of a topcoat in another article.
Pictures, as they say, are worth a thousand words. Because visiting us isn't convenient for you, here's a photo of an e-coated sample before and after 500 hours of a salt spray test.
Check out our E-Coat Top Coat page. This page provides before and after sliding scales for 500, 1,000, and 1,500 hours of salt spray testing.
Reading about e-coating's effectiveness is one thing; seeing it is another.
The two-coat finishing process is excellent for reducing both corrosion and surface imperfections. It's cost-effective, easy to maintain, and one of the best ways to protect your investment.
E-coating offers a wide range of protection. Electrolytic and anodic processes help reduce corrosion, while cationic and organic processes can protect against UV light and impact. The best part about e-coating is that you can change the coating in the future to provide more protection or durability.
If corrosion protection is the primary need, use a preferred process, such as a cationic or anodic process. This finishing process coating is always looking for more applications in the manufacturing industry. If you're interested in more information about e-coating, contact us using our contact form.
If you want to learn more, please visit our website Aluminium Coil Coating.