What is powder coating? – Powder coating is a dry painting process that uses a fine powder with the consistency of powdered sugar, and an electrical charge to coat an object. Then the piece is baked in an oven at 400+ degrees Fahrenheit to make the powder melt and flow together. Once it is cooled and cured the powder coat has formed a solid plastic coating over the entire surface that is much more durable than regular paint.
How does the powder stick? – When initially applied the powder sticks to the part the same way a balloon will stick to the wall if you rub it on your head on a dry day. An electrical charge is applied to the powder, and the opposite charge to the part to be coated. The dry powder in the air is attracted to the opposite charge and sticks. Until you bake it though, the powder can be easily brushed off. It needs heat to make the powder flow and form a permanent coating.
Is powder coating durable? – Yes. Powder coating is more durable than even baked on enamel in most applications. Powder coating is better protection against rust and corrosion, and resists scratching and shipping better than paints too. It is also much more resistant to chemical solvents too.
What colors are available? – There are literally hundreds of colors of powder available including candy, clear and sparkle finishes. Plus you can get gloss, matte and even textured finishes.
What can and can’t be powder coated? – Typically powder coating is best used on parts made of an electrically conductive material that will withstand the 400 degree baking process. There are however some specialty powders that can be used on non-conductive parts, and some that flow at a lower temperature. Powder coating is best for metal parts that live in a rough environment, like underhood and undercar chassis parts.
What shouldn’t I powder coat? – Powder coat tends to be thicker than traditional paint. Therefore using it on intricately detailed parts can leave them looking like they are in soft focus, with much of the sharpness gone. Also, avoid applying powder coat to critical surfaces: threaded parts, shaft holes, etc. Mask or plug these with special high temperature tape or plugs.
How hard is it to apply? – If you can spray wet paint you can learn to powder coat with little effort. Plus, there is much less risk of drips and runs with powder coating.
Is it environmentally friendly? Is it safe to spray? – Powder coating is much better for the environment than even spraying water borne paint. There is barely any waste or overspray, and no volatile organic compounds, or solvents evaporating into the air. For the person spraying it is much safer too. You need to keep from inhaling the powder, but there are no toxic chemicals that can be absorbed through the skin or anything, like many sprayed automotive finishes.
How can powder coating be removed? – Before curing it will just brush off. After curing there is not much that can remove powder coating. Eastwood offers a Paint and Powder Remover solvent that will take it off, as will many Methyl ethyl ketone and Acetone strippers. Powder can also be removed with bead blasting, grinding or other mechanical means.
How can I get a smoother finish? – Powder coating can be sanded afterwards just like color sanding paint. Start with 400 grit to knock down the orange peel and any imperfections, and get progressively finer.
Can I use my kitchen oven to cure powder coat? – A kitchen oven can be used to cure powder coat, but you should never use one you plan on making food in again. The powder coat can leave a residue in the oven that will make everything taste plastic, and at worse it can actually make you sick. Buy a toaster oven for small parts, or a kitchen oven used on Craigslist.
Can overspray powder be reused? – Yes, after spraying just sweep up any over sprayed powder that didn’t stick. This is a good reason to build a dedicated spray area or booth for powder coating. You can spray up to 50% reclaimed powder in each project.
What is the Faraday or halo effect, and what can be done about it? – The Faraday or halo effect is the way in which powder will behave due to the laws of physics around holes, openings and in tight corners. In order to deal with it you may have to lower the voltage on the gun, turn the voltage off entirely, increase the air pressure, or move the gun closer. Practice shooting irregularly shaped objects so you learn to deal with this problem before it matters.
Do I need to take any special precautions with my air supply when spraying powder? – Yes, but no more than when spraying paint really. Use a good water separator on the air line, as well as a pressure regulator, and you should be fine.
Do I need a dedicated spray booth? – No, certainly not. But, if you want to not waste powder, sweep it up and respray it, you need to be able to easily collect it and have it still be relatively clean and dry. This is much easier to do from the floor of a dedicated, clean spray booth, even one that is just 3 ways, a floor and a ceiling of plastic drop cloths.