Liquid paint or powder coating are the two possibilities when electrostatic is the method of choice to apply a finishing.
Electrostatic liquid painting has been out there since the 1940s when William Ransburg invented the first equipment to apply it. Later, in the early 1950s, a German scientist developed a process to apply powder coatings efficiently.
Since that time a heated debate about what process is best has taken place. Each has advantages for manufacturers and oftentimes both are needed. Both coatings (liquid and powder) can be applied electrostatically.
There is no obvious winner, because the answer may depend on the kind of application, products involved, along several other factors.
The purpose of this article
So, the purpose of this article is to let you know the pros and cons of electrostatic powder coating vs liquid paint based on 5 factors, which are:
But first, let’s take a look at the main features of each process.
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What is electrostatic powder coating?
Powder coating is the process of applying a fine, dry, free-flowing powder material to a metal substrate and baking it to form a both durable and decorative coating.
The powder coatings are based on polymer resin systems, pigments, and other additives which are ground into a powder. Several powder coatings are depending on whether it is made of acrylics, polyurethane, polyester, polyester-epoxy, or straight epoxy.
The powder coating may be a thermoplastic or a thermoset polymer. They differ in that while thermosetting makes use of chemicals that react to the powder when heated, thermoplastics melt and set into the coating upon heating, and no additional chemicals are involved in the process. The way of applying both polymers is almost similar and the resultant appearance is identical.
During the application stage, the powder coating is transformed and an electrostatic process causes the powder to adhere to the surface. At that time the powder granules and the surface are jointly charged with volts of electrostatic energy.
The heating of powder coating should be done in an oven for 10 minutes under a high temperature of approximately 400 degrees Fahrenheit (200 degrees Celsius). This melts the powder, allowing it to wrap around the object, all the while binding the polymer into a network-like polymer finish.
Some products usually are powder coated are bicycles and household appliances.
What is electrostatic liquid painting?
We call liquid electrostatic painting the process where paint is sprayed from a gun to a surface by the action of an electric field. Depending on the application, more equipment could be required.
Like the case of any other spray painting, applying liquid paint by electrostatic is a threefold process: First, a primer should be applied. Later, the base color. Finally, the enamel is applied to the piece.
In most cases, the pieces are dried by air. Depending on the paints used the drying time frame could be anything between 1 to 24 hours.
Just in a few cases, the drying can be done by an oven. If that is the case, lower temperatures than the ones used for powder coating should be needed.
Some products that are finished using electrostatic liquid paint are cars, wooden furniture, metal structures, etc.
In the video here you can see a Ransburg electrostatic spray gun in action.
What are the key differences between liquid paint and powder coating
Just by describing them, we can see a few key differences between the electrostatic powder coating and liquid painting. To have two options or more to choose from is a normal way to go for industrial processes.
So, from now on, we are going to dig into five key differences between electrostatic powder coating and liquid paint. The topics to be discussed are which one is more durable, cheaper, offers better quality, is easy to apply, and is safer. Let’s go for it.
1) Which one is more durable
When establishing the difference between these two processes regarding durability, we need to take into account that the conditions the pieces coated would face may be quite diverse.
Some products are directed to heavy-duty; others to be exposed to weather conditions; others to salinity, for being located on a shore, etc. Is well known that the sea affects metal greatly.
In some cases, the products are directed to indoor use, like appliances at homes, or are just internal parts for other products. Those pieces are going to have less wear and durability is estimated to be longer.
Some people state that, with low maintenance, both powder-coated and liquid painted pieces can last in good standing for an average of 10 years. So, using one or the other process varies little the lasting of the piece.
The maintenance is very similar in both processes. What is needed is to keep the piece or product clean and free of pollution agents, like oils and saltpeter.
So, regarding durability, both processes perform well.
2) What about the costs
In this regard, there is a huge difference between coated powder and liquid paint.
Costs related to electrostatic powder coating
For applying electrostatic powder coating a sealed premise (paint booth) is needed. After coating, the pieces need to be baked (the curing process) in a special oven.
Depending on the space available and the budget of the company, this oven can be big enough for the coated pieces to run on it for the 10 minutes length of baking time. Another option, if the oven is not big enough, is that the coated pieces can be baked in batches, which can form a bottleneck in production.
In any case, the initial investment of a specialized paint booth and an oven for curing powder coating can reach several hundreds of thousands of dollars. That is an amount of money not many companies can afford, much fewer hobbyists.
In line with that, if powder coating, the company needs facilities big enough for having such a booth and oven. Is ideal to set up all this equipment for good.
As distributors of MS Powder and BGK, we have several industrial types of equipment that can be suitable for this application.
Costs related to electrostatic liquid painting
In contrast, electrostatic liquid painting can be done both on-premises as in situ. A painting booth can be good in certain situations but is not required. No oven is needed. So the initial investment reduces greatly.
The required equipment for electrostatic liquid painting is a spray gun. The Ransburg Ransflex and Vector are among the best seller electrostatic spray guns. They have versions for both manual and automatic applications.
If the painting is going to take place in a workshop, this space needs to meet some requirements. In this article about electrostatic spray we explain that matter.
Also, electrostatic liquid painting equipment has become more and more common, so spare parts and repair labor is easy to find and affordable.
So, when thinking about necessary investment, electrostatic liquid paint is a clear winner.
3) Which one gives a better quality
The concept of quality in a process depends greatly on what is measured. When talking about quality in this regard many people think of the result and that the coating achieves the purpose.
Both processes can have an outstanding good looking appearance. But to achieve that each one of them have obstacles to overcome.
In the case of powder coating, the pieces to be painted should be carefully cleaned of any dust particles, oils, and other contaminants. A whole cleaning process should be applied to the pieces.
If the pieces don’t get properly cleaned, some defects are going to be shown after baking, like an orange peel finish. No touch-up is possible. The pieces affected should be stripped and cleaned again to be coated.
Regarding electrostatic liquid painting, there is the danger of over-spraying the pieces and having some saggy points around the surface. This depends a lot on the expertise of the operator and the quality of the equipment. Ransburg electrostatic spray guns are well known for achieving a uniform spray.
In any case, touch-ups are possible, so the time required to fix any error in production is low.
Liquid paint colors availability
When evaluating quality we need to think too about the variety of colors available from each process. In this, electrostatic liquid painting offers a lot more.
Powder coating offers a small number of colors and they cannot be mixed by the user. They should be used directly from the manufacturer. Many of the finishes are mate.
That is why some people think that powder coating offers textures while liquid paint offers colors.
The truth is that there is a huge variety of liquid paint out there. Some manufacturers offer over 200,000 different colors.
They can be mixed by the user to create something unique. Indeed, with liquid paint, a lot of effects on the painted surface can be reached.
A glowing, metallic finish is commonplace in pieces coated with electrostatic liquid paint.
Then, regarding quality, each process offers different things. Based on your needs you can make a decision.
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4) Which application is easier or even possible
Since the electrostatic process is so easy to do, no special expertise is required from the operators, no matter if they are going to use powder coating or liquid painting.
In some cases, powder coating is not possible at all. Since for powder coating an oven is required, this process only can be applied to parts that can be transported to the premises. If the piece should be coated in situ, there is no way powder coating could be applied.
This means that contractors who go to places to paint surfaces, parts, or equipment, only can work with electrostatic liquid paint.
Another reason for avoiding powder coating could be the nature of the material itself. The parts to be coated need to be heat-resistant. So, for example, rubber cannot be powder coated.
In these 2 cases, electrostatic liquid paint is not only a better option but the only option.
The expertise of the operator
The expertise of the operator is also another factor to think about. In the case of powder coating, if the operators do not clean the pieces properly, the whole process will fail. The surfaces should then be completely stripped and the coated redone from scratch.
When painting with liquid electrostatic the operator should be careful enough to avoid runs or drops around the surface. Then, in both cases is needed an expert operator.
Now that we are considering mistakes when applying coatings, it is worth it to mention that liquid paint can be touched up immediately to fix any possible problems. This is not possible for powder coating.
Changing colors is easier with liquid paint
Electrostatic liquid painting has another advantage: changing colors is easy to do. This is especially important for medium and small manufacturing companies who may have just a few or only one designated place for painting. So, changing colors for them is critical to complete production.
The pre-production process is also a big difference between electrostatic powder coating and liquid painting. Since for powder coating the pieces are required to be immaculate, there is a whole pre-production process to carry on.
To be powder coated, a part should be completely free of debris, oils, dirt, moisture, residue, and dust. This matter is not that complicated when applying electrostatic liquid painting.
Finally, it is fair to bring out that more materials can be finished with electrostatic liquid paint because it does not require them to be necessarily conductive. So, materials like rubber, paper, ceramic, glass, porcelain, and plastic need to be coated with electrostatic liquid paint. It is sufficient to apply a conductive primer before electrostatic painting.
Then, regarding several aspects of the application, electrostatic liquid paint is the way to go.
5) Which one is safer
Even though electrostatic liquid paint has a lot of advantages, it is safe to say that powder coating throws away less VOC (Volatile Organic Compounds) to the environment.
This is possible because there are almost no toxins or VOC found in powder polymers. Also, when applying it, the unused powder can be collected and stored, instead of flying away from the booth.
So, we can say that electrostatic powder coating is better for ecology.
Nevertheless, for applying both processes operators should be properly covered with safety overalls and respiratory protection. Some safety procedures to prevent electrical shocks should be carried out.
Just in a few words
So, with all that aforementioned, we can have a bigger picture about what process is the right one for your application.
If you are going to set up a production plant for manufacturing household appliances and have a big budget to get all the equipment you possibly need, powder coating could be an option for you.
But in almost the rest of the cases, you will find that electrostatic liquid paint can be a good fit for all your needs.
This is because electrostatic liquid paint is:
- Easy to apply
- Do not require expensive equipment
- Can be applied in any area, not just on your premises
- The equipment parts are easy to find and cheaper
- Offers a wide variety of colors, that can be mixed
- Can be touched up, if needed
- The coating layer is lighter
You can count on us to help you to figure out a customized painting solution that meets your needs.