JCL Precision Part Co.,Ltd.

Ultimate Guide of Powder Coating

Table of contents
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1、What is Powder Coating?

     1.1 Ingredients of Powder Coating 

     1.2 What Are The Types of Powder Coating?

2、How Does Powder Coating Work?

3、How Does The Coating Process Look Like?

     3.1 Blasting

     3.2 Pretreatment

     3.3 Masking

     3.4 Coating

     3.5 Curing

4、The Advantages and Disadvantages of Powder Coating 

    4.1 Advantages 

           4.4.1 Durability

           4.4.2 Environmental FriendlyVersatility

           4.4.3 Cost Effective

           4.4.4 Aesthetic Look

    4.2 Disadvantages

          4.2.1 High Set Up Costs

          4.2.2 Size

          4.2.3 Sensitive to Heat

5、Conclusion

6、FAQs


Do you need help deciding whether to choose powder coating or paint? The paint finish is a traditional way to color your metal fabrication. Still, an invention like powder coating is more reliable, durable, and tougher than the former, making it long-lasting. There are many reasons why  electrostatic powder coating overshadows liquid paint these days. 


Do you want to know more? We have created a complete powder coating guide for you.


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What is Powder Coating?

Powder coating refers to covering a dry, clean, and charged metal piece with dry powder inside an oven. The oven’s heat causes the powder to melt, covering the entire metal. The molten powder then cools down and dries up to become a tough coating. The powder sticks to the metal even after curing due to an electrostatic charge that holds attracts the powder particles onto the surface. 


Ingredients of Powder Coating 

Powder coating requires a concoction of different ingredients. They include:


Resin

A resin such as epoxy or polyester is used, which is the core of the powder coating. 

Pigments

Pigments are grounded particles that show their true colors once the coat has been cured.

Curing agents

These agents help in curing (hardening) the coating. The type of curing agent used depends on which resin you are using. 

Extenders

Extenders help enhance the look of the coat, e.g., by providing better texture.

Additives

An example of additives of flow aid that helps the coat to flow smoothly in the oven. Other kinds of additives are added to improve performance.

Post additives

These prevent the powder from clumping so that the texture and color turn out smooth. As their name suggests, they are added in the end.

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What Are The Types of Powder Coating?

There are two kinds of powder coating. We will break them down to you. 


Thermosets

Thermoplastics 

  • Thermosets become a thin and soft  liquid when heated.

  • Thermoset coating forms a chemical bond that is different than the core resin. This means it is not recyclable, and the coat is permanent.

  • It offers greater scratch resistance and many options, e.g., polyesters and hybrids.

  • The coating itself is less thicker compared to thermoplastic, making it more physically appealing.

  • It is a cheaper process than thermoplastic coating.

  • Thermoplastics are thicker and, thus, are comparatively more durable.

  • The thermoplastic coating does not undergo any chemical change and, therefore, does not form a chemical bond. This means under certain temperatures, the coating will melt, which makes it reusable. 

  • Several coats may have to be applied to achieve the desired look.

  • It is easier to retouch when the coating is scratched or ruined since there is no chemical bond.

  • The coating cannot stand high temperatures since it will melt.



How Does Powder Coating Work?

Powder coating works due to an electric charge, which helps it to stick to the surface. 

An electrostatic paint sprayer must be used to spray the dry powder onto the surface. The sprayer passes on a positive charge and then sprays it onto the object, usually a metal. 



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How Does The Coating Process Look Like?

Blasting 

The blasting process is used to take off any unwanted materials. Abrasives are used to remove previous paint, weld, rust, and other inorganic contaminants. Without blasting, the object would have an uneven, rough finish once the powder cools down.

Pretreatment 

The object needs to be fully cleaned before spraying, and therefore it goes through pretreatment. The pretreatment process includes:

  • Chemical etching: achieved by an alkaline cleaner taking of oxides and any other contaminants and liquid.

  • Phosphate application: this makes the object corrosion-resistant and more adhesive to powder coating. The phosphate solution is then removed.

  • Water rinse: This is a reverse osmosis water rinse that removes any residuals from the surface. Then, a sealer is used to seal the surface. 

Masking 

Masking refers to covering the parts of the surface/ object that you do not want to be colored. This blocks the powder from reaching and melting onto those parts. Masking can be done by using high-temperature tapes or silicon plugs for holes. 

Coating 

Coating is done by using an electrostatic paint sprayer or an automatic system depending on the size of the business. Generally, hobbyists can also use electrostatic paint sprayers since some are quite inexpensive. 

Curing 

This part refers to letting the powder cool and harden. The oven’s temperature is decreased depending on the type of powder coating and the amount of coats.


The Advantages and Disadvantages of Powder Coating 

Advantages 

Durability 

Powder coating comes with greater durability than its counterparts, thanks to the electrical bond. On estimation, it can last for as long as twenty years, but several factors can make it wear down faster, e.g., UV rays. Nonetheless, it is still a better alternative. 

Dealing with this is very easy: use epoxies for indoor objects and fluoropolymers or urethanes for the harsh outdoor environment.

Environmental Friendly 

With powder coating, you do not need to use any solvent or primers, significantly reducing environmental harm. Unlike paint, there is not a lot of overspray, and any overspray in powder coating is non-toxic and easily reusable. 

The health concerns related to powder coating are also not threatening or chronic.

Versatility 

Powder coating can be used not only on metal but also on other materials, such as plastic. Wood is also a suitable candidate, but only after specific pretreatments. 

Cost Effective 

Though powder coating initially comes with high set-up costs, it is more cost-effective in the long run than traditional painting. Powder coating lasts longer, so the maintenance cost is low. translucent powder coat,

Aesthetic Look

Powder coating can give off many different finishes, such as polished looks, grainy textures, or even a  depending on what the customer prefers.


Disadvantages 

High Set Up Costs 

Compared to traditional painting, powder coating comes with high set-up costs. You will need a large powder curing oven to melt the powder and cure it, along with other equipment such as powder coating guns, air compressors, etc. 

Size

You can powder spray anything as long as it fits inside the oven. This comes with a disadvantage because you are limited by the size and cannot powder coat larger objects.

Sensitive to Heat

As the powder requires high temperatures for melting, some types of plastic cannot be coated. This may be tackled by some sort of pretreatment, but the risk of melting persists. For plastics, thermoplastic coating may be better since it requires lower temperatures to melt. UV powder coating is also another option since it uses UV rays to cure the powder, resulting in lower curing temperatures (around 120 degrees Celsius).



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Here is an overview of the advantages and disadvantages:

Advantages 

Disadvantages

  • Durability 

  • Environment-friendly 

  • Versatility 

  • Cost-effective 

  • Aesthetic look

  • High set-up costs 

  • Size limitation

  • Heat-sensitivity 

 


Conclusion 

Powder coating offers great durability, versatility, and longevity, which cannot be compared to traditional painting. Despite the high setup costs, powder coating is more cost-effective in the long run, e.g., lower labor costs, if you are a metal finishing service. Even if you are a hobbyist, powder coating will elevate your work and make the process faster. We recommend powder coating over traditional painting any day.




FAQs

Which type of powder coating is the best?

For indoor objects, epoxy powder coating is the best, especially as a corrosion resistant coating. They also provide amazing durability. For outdoors, which have a harsher environment,  fluoropolymers or urethanes are the best.

Is powder coating dry or wet?

Powder coating is a dry concoction consisting of several particles, such as resins, pigments, extenders, etc. These particles are melted and fused together during the curing process to form a uniform coating on the surface. Unlike traditional painting, powder coating does not require any solvents or primers.

How can you tell if powder coating is good quality 

A good way to find out is to check the smoothness and the look. If the finishing is rough (when it was not the intention), then it is a good suggestion that the powder is of poor quality.






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