Powder Coating is an advanced yet simple way of spray-painting a very fine, dry plastic powder paint onto a metal surface. As the powder paint cloud gently leaves the front of the spray gun, it is charged with static electricity. The charge attracts the powder paint to the part that requires coating. The part is then placed in an oven, where it bakes at 400 degrees Fahrenheit for 10 minutes. While in the oven, the powder paint melts and flows into a beautiful and durable finish. Primers are not necessary. And there are no unsightly runs or drips, as often results with the use of wet paint. Prior to baking, powder coating is very forgiving of coating mistakes. Because it is powder, the paint can be blown with a low-pressure air nozzle, quickly and easily covering up the mistake.

However, after the powder cures in the oven, mistakes can only be removed by sand blasting or burning it off. A cold liquid stripper is available but it is slow, extremely hazardous and could damage the metal itself. Recoating over an existing finish is difficult but possible.

Even more important, powder coating is environmentally friendly. That's because the over-spray is reused. And with no solvents, powder paint does not pollute the air.

Frequently Asked Questions (FAQs)

Must I buy an oven to do powder coating?
Yes! If you cannot get an oven, don't waste your time reading this. The bottom line is: You must have an oven that will allow you to bake items at 400 degrees Fahrenheit for ten minutes--or you cannot powder coat! Let's be honest: Your most expensive investment will be the oven.

How big of an oven do I need?
Only you can answer that question. Ask yourself: What size are the items I plan to powder coat? How many items would I like to powder coat at one time? Obviously, the larger the oven, the more products you can powder coat at one time. You have many choices. Your oven could be a small 6' x 8' x 10' walk-in gas oven priced at $30,000. Or you can choose a 100' oven with a pass-through conveyer priced at $100,000.

Should I buy a gas, electric, or infrared oven?
Both gas and electric ovens work well. And infrared ovens work well if designed properly. However, electric ovens take longer to reach the proper baking temperature. Obviously, the faster the oven heats up, the faster your products will be powder coated.

What size powder spray gun do I need?
Many ask for a small, inexpensive spray gun because they are "only going to be coating a few small parts at a time." Sorry, but one size fits all! There is no relationship between part size, coating time, and powder spray gun size. However, the powder supply hopper that feeds the powder spray gun is available in several sizes. And there is a relationship between the number of powder guns and the size of the oven. If the oven is large enough to coat many parts, more spray guns can be used, which can greatly increase your rate of production.

Does PCF sell powder spray guns?
Yes! PCF has the best powder spray equipment made today. Our complete manual powder spray gun system, priced as low as $4,250, can be shipped to you for next day delivery.

I've tried powder coating in the past and had a bad experience with a spray gun. Are powder spray guns really the best choice for powder coating?
Settle for nothing less than true industrial type powder coating equipment. Unfortunately, many individuals trying to get into the powder coating business get the wrong impression of powder coating after using a "toy" type powder spray gun. One powder spray gun on the market today requires two hands to operate and charges the powder with only 16 kv. What's more, the instructions suggest using the manufacturer's $23 per pound powders and a kitchen oven for curing the parts! Incredibly, that manufacturer advises the user to sweep up the overspray powder.

To ensure proper coating, while also saving time and powder, the spray gun must charge the powder with a high voltage--80 kv or more. Proper control of the coat's thickness can only be accomplished by using equipment with a high voltage adjustment control and dual powder controls. The "toy" spray gun discussed above has none of these options! A spool of what the manufacturer calls "safety wire" is supplied to hang and electrically ground the part being coated. With our high voltage electrostatic spray equipment, you only need a simple paper clip to hang the part you're coating.

Is a spray booth necessary?
Absolutely! The main purpose of a spray booth is to keep the powder overspray contained. This is of utmost importance because breathing in powder spray dust is hazardous. What's more, if the dangerous mixture of Air, Dust, and a spark of Ignition (ADI) can cause a dust explosion.. The PCF Model P1300 Air Velocity Meter gives you a method to measure the air velocity at the powder spray booth openings. These air velocity readings should average between 80 fpm and 100 fpm.

The secondary purpose of the spray booth is the economical reclaim of powder overspray. For example, a company that uses only one color can easily reuse the overspray, saving the company a lot of money over time. Powder coating does not waste paint as a wet paint system does, forcing companies to throw out the overspray with the dirty filters.

That's great for companies that use only one color. But what if my business powder coats in many colors?
Reusing powder overspray can cause a slight problem for those who paint with several colors. To prevent cross-color contamination, the entire powder booth, reclaim recovery system, and powder spray gun must be cleaned of the old color before the new color is used. This can take a lot of time, depending on the number of guns used, as well as both the spray booth and recovery system size. The decision not to clean between color changes, known as "Spray to Waste," is strictly an economical choice. Obviously, if you choose to clean, the value of the powder saved must be more than the cost of labor and lost production time. And remember that there are two clean-ups in a single color change: the clean-up from the original color to the new color, and the clean-up returning back to the original color.

Can I use a vacuum cleaner to pickup the powder overspray?
Yes. However, you cannot use a shop-type electrical vacuum. This kind of vacuum has internal electrical workings that spark during operation. The electrical spark could easily cause a dangerous dust explosion. Yet, a vacuum with an explosion-roof electrical motor is overkill. We recommend that you use an air-operated vacuum cleaner.

Do you use different types of powder for different jobs?
Yes. There are two basic types of powder: epoxy and polyester. Both epoxy and polyester powder paints come in a rainbow of colors, glosses, and textures, and both outperform most wet paint finishes. The epoxy finish is the most durable, but has one drawback: It will chalk and dull from the sun's ultraviolet rays. The same is not true for polyester paints. Therefore, most indoor powders are made of epoxy, while most outdoor powders are made of polyester.

Note: PCF does not make the powder paint. PCF makes the powder equipment itself and also the after market powder parts for all major powder equipment. Just click on the word DIRECTORY to get an up to date listing of all the powder mfg. in North America.

What is a TRIBO powder gun?
Tribo is the word used to describe a static charge that occurs when two different items are rubbed together. For example, tribo charging happens when dragging your shoes across a carpeted floor. A tribo spark discharges when your hand gets shocked from touching a metal doorknob. This same tribo charging happens when epoxy powder moves through a Teflon-lined powder gun barrel. As the epoxy powder rubs against the Teflon surface, an electron (-) in the powder is transferred to the Teflon. The epoxy powder now has a positive (+) tribo charge.

A tribo powder gun precisely applies a very thin coating to an item. It can easily coat tight, recessed areas. A tribo gun also recoats well, so it's usually used to apply a protective clear coat, when necessary, over a first coat.

Sounds great! Are there any drawbacks to using a tribo powder gun?
Tribo guns have two weak points. First, it coats at half the speed of a corona-charge powder gun. Second, it works best with epoxy powders.

A tribo powder gun should have very long gun barrel. The longer length increases the inside surface area of the thereby increasing the tribo charging. Be careful to spray the powder consistently. The tribo charging effect decreases if powder is sprayed too quickly, because not all of the powder will rub on the interior barrel surface.

You said that the tribo powder gun works best with epoxy powder. But I have seen non-epoxy powders labeled"tribo powder." Are these powders as effective?
It's true that some non-epoxy powders are considered "tribo powder." But this is only because the powder has been chemically treated by the manufacturer to tribo-charge like epoxy powder. This effectiveness of this treatment can vary from manufacturer to manufacturer.

Can you tell me about a corona-type spray gun?
Most powder spray guns are corona. A CORONA type gun charges the powder using a high-voltage power supply. The corona spray gun charges the powder negatively (-). Only a few positive (+) corona guns are in use; they seem to do a better job with special powders, such as nylon and Teflon.

Corona spray guns have several drawbacks. First, the corona gun makes it difficult to cover recessed areas and tight corners with powder. Using a high-quality powder that retains the high-voltage charge best controls this problem.

Second, recoating a part that has already been cured is difficult with a corona spray gun. The best solution for this problem is to lower the gun's high voltage output 50% or more. Then, gently dust the part with powder until it is fully covered.

People who know little about electrostatic coating often think of it as a kind of voodoo that magnetizes the paint or part. But there is no voodoo--or even magnetism--involved. And nothing is done to the part being coated. We simply charge the powder paint by either adding or removing electrons. The electron is inherently negative. When the paint is negatively charged with an excessive amount of electrons, the paint is attracted to an object that has fewer electrons. We can also charge the paint positively by removing electrons from the paint. With fewer electrons, the paint is attracted to an object with a greater amount of electrons.

Ground is the best, but not the only, source for obtaining or discarding electrons. Remember that it is the excessive collection of electrons that creates the negative charge and it is the excessive removal of electrons that creates the positive charge. The belief that a powder filter media made with a metalized or conductive surface cleans or releases powder better than the non metalized media is "Hog Wash"! If this were true, than the every day metal parts we coat would not attract and hold powder! I would think a non-conductive filter media would not attract charged powder, making releasing and cleaning of powder from the filter media much better! Note: Parts that have been powder coated and not yet cured will have the powder cling to its surface for weeks.

Are there any drawbacks to powder coating?
Unfortunately, chipping is the main problem with powder coating. Often chipping results because the part was not baked long enough and/or kept at the proper cure temperature.

What is "grounding"?
The term "grounding" is the most misunderstood issue in powder coating. Grounding will be the least of your coating problems. Yet, grounding will be blamed for paint chipping and light coverage or no coverage in corners and tight areas. Because powder is charged with high-voltage of 80 kv or more, a very low resistance to ground is not necessary. A typical voltmeter powered by a 9 volt battery is useless in measuring the thoroughness of ground for electrostatic coating. This test should be done using a megaohmeter. But its usefulness will be limited. It is the amount of surface area being coated that will determine the toleration of paint build-up on the hanger before the hanger must be cleaned. The larger the surface area for charged powder to collect, the greater the energy level on the surface will become. It is the level of electrical energy that develops on the surface of the part being coated that will determine how poor grounding condition of the hanger or conveyer before it must be cleaned. If we attempt to coat a part with a small surface area using a hanger with a heavy paint build-up, the part will not accept charged powder. Taking an identical hanger with the same heavy paint build-up and try coating a part with a much larger surface area part and you will coat with no problem! Under test conditions, a refrigerator liner, which has an extremely large surface area, was hung with an insulated hanger. The liner using the insulated hanger was then placed on a conveyer for normal coating production. As the liner pasted through the spray booth, the liner surface became an electrical capacitor, which produced several very long electrical arcs that jumped from the refrigerator liner to the spray booth wall. The arcing that took place indicated that at the moment of each arc, the liner had discharged the excessive amount of electrons that had accumulated on its surface and that the liner had returned to a neutral condition ready to accept more charged powder. After the test, the coating thickness on the liner tested was compared to that of normal liners coated with clean hangers. With a digital measuring equipment, little difference if any was found. Under no condition should electrostatic coating continue if sparking exist! If you are told that your spray gun coverage will improve by cleaning the hangers or conveyer, reconsider. First try using a long grounding wire to those parts in question. If you truly see a definite improvement in coverage using a grounding wire, then clean the hangers and conveyer line as you would for normal maintenance. Don't be surprised if you see little or no improvement in coverage. Cleaning of the hangers and conveyer system will only reduce the sparking or arcing condition, which in turn will improve the safety conditions for electrostatic coating.

I've heard that many people get shocks while using electrostatic equipment. Is this true?
Electrostatic equipment operators may complain of getting shocks. In most cases, these shocks are due to mistakes made by the operator. He must be continuously grounded while using the equipment. While grounded, he must not touch a part that has a static charge. His touch causes the part to discharge a shock.

Shocks also result when an operator wears a glove, or if the equipment grounding is defective. In both of these instances, he will unknowingly develop a static charge that will build and finally discharges through the glove or to any grounded object he touches. Unfortunately, this situation often happens to site visitors. That's why many people determine that the equipment is dangerous.

What is "metallic powder"?
"Metallic powder" results when very fine metal dust particles, such as aluminum, are blended into the powder during manufacturing. This aluminized look is very attractive, but weathers with time. Its other drawback is "loading." Loading is the uncontrollable loss of electrostatic high-voltage power at the tip of the spray gun. "Loading" happens because the metallic powder has created an easier ground path through the powder hose for the high voltage to travel. A specially designed spray muzzle can help control this ground problem if the amount of metal used in the powder is not excessive. Metallic powders are sometimes blamed for causing spray booth fires.

How well do electrostatic spray guns charge?
This question can only be determined by testing at the tip of the sprayer with a non-loading voltage tester. (Here the term "loading" means that the voltage tester will not affect the actual electrostatic output of the equipment while performing the test.) PCF has been manufacturing this type of test meter since 1978. Most manufacturers of powder coating material use the Model HV-100 in laboratory and field service. It has become the industry standard for electrostatic spray gun testing.

If you are lucky enough to have equipment with a high-voltage dial, it will show the relative high-voltage output. There is one particular equipment manufacturer that made a system which indicated maximum high voltage gun output even though there was none at the tip of the spray gun. A wire in the gun cable would break, or a plug at the back of the gun would fall loose, resulting in absolutely no voltage at the tip of the spray gun--even though the gun was still spraying powder, and the high voltage dial showed that all was well!

Why is powder spray equipment made of plastic? Does that mean it's cheap in both price and quality?
You'll notice that much of the equipment used in powder spray painting is made of plastic. Plastic is not used to save the manufacturer money. Instead, plastic is a used because it is the safest material. The only part of the spray pistol that should be metal is the handgrip. The metal handgrip grounds the spray gun operator only if the operator is not wearing a glove.

I'm convinced that the spray system must be made of plastic. But should I choose Delrin, Teflon, or Polyethylene?
Plastics used in spray system construction are made of Delrin, Teflon, or Polyethylene. Delrin is used primarily in low-voltage areas. Delrin does not perform very well in high voltage areas because it will yellow and crack. Delrin also becomes a poor electrical insulator. Teflon is used in high-voltage areas where impact fusion, or hardening of powder, in the spray equipment is a problem. If the entire spray gun were made of Teflon, it would not break, clog, or deteriorate from high-voltage. But it would be very expensive and very heavy. If wearing of Teflon gun parts were too excessive or costly, then your next choice is glass-filled Teflon. If expense or clogging is still a problem, the final and best choice is High Density Polyethylene (UHMW, Tivar, Tefcell, etc). Over 75% of all parts manufactured by PCF are made from UHMW. That's because of its light weight, wearability, and efficiency when used with high voltage. If your UHMW powder gun or pumps still clog, you will need to go back to parts made of Teflon.

Note: In general, injection molded plastic parts do not have the same wearability and electrical properties as machined plastic parts.

If you decide at this point that you would rather have a custom powder coater job shop do the powder coating for you, just click here for a DIRECTORY of Custom Powder Coaters in North America.