Powder coating is a process by which a coating of pigment is applied to the surface of an item to create a layer of color that is brighter, thicker and much tougher than conventional paint. It involves the use of a dry powder which is sprayed onto the cleaned surface of the item in question. The powder is held on by means of an electrostatic charge imparted to it by the specialized spray gun that is used. This powder is made of a special thermoset polymer, which responds to heat. When the powder is baked, it reacts with other chemical groups in the powder polymer and increases the molecular weight and improves the performance properties of the material, creating a smooth and uniform layer of pigment. This process is used primarily on metals because of the high temperatures that the powder must be cured at. One will most commonly see power coats on processed aluminum goods and appliances as well as automobile and motorcycle parts. Here is a guide on how to powder coat any metal item.
Things You'll Need
- Corona gun
- Powder paint
- Convection cure oven
- Safety goggles
- Air compressor
- Chain and winch
- Grounding wire with alligator clips
- Large and open work space
- Sandblasting particulate
Begin by stringing up the metal item on a chain and hauling it off the ground with your winch. This is effective for large metal objects up to several hundred pounds in size. If you wish to powder coat a larger item it will have to be disassembled and then strung up. Before you can begin coating the item you must first clean it of all surface materials: scale, oil, grease, rust, etc. To do this you could dunk the item in several chemical baths, but the size of these baths and their cost makes this an inefficient method. A better choice is sandblasting.
Don your respirator and safety goggles first. Then connect your sandblaster gun to your air compressor. Make sure to fill the sandblaster’s reservoir with specialized particulate and then spray every surface of the hanging metal item thoroughly.
Clean the area with a broom before continuing further to make sure that you’ve gotten all your sandblasting particulate off the floor. If you are working outdoors then you won’t need to do this. You will also be unable to recollect the excess powder lying around once you’ve finished. The reason for doing this is that, if you recycle the unused powder coat, you do not want to get this mixed up with the abrasive granules of the sandblasting material.
Disconnect your sandblasting gun and set it aside. Connect the corona gun up to your air compressor, making sure to plug its electrical cord in if you have a model that does not use batteries. This gun needs to have electricity while it runs so that it can impart an electrostatic charge to the powder. Fill the gun’s reservoir with powder coating and make sure to keep on your goggles and respirator. Clip the grounding wire to the chain holding up your metal item so as not to create a spot on the item which will be covered. Simply spray the surface of the item in short, sweeping spurts as if you were using spray paint in order to evenly coat the item.
Swing the winch over to the curing oven and lower the metal item inside. Remove the chain and close the oven’s hatch. Set the oven to 400 degrees F and cook the item for 10 minutes to allow the powder coat to cure. Open the hatch and allow the item to cool for a few more minutes before reconnecting the chain and hauling the item out of the oven.
Go back to your work area and sweep up all the excess powder so that it may be reused some other time.
Tips & Warnings
- There are many advantages to using the powder coating process as opposed to traditional liquid-coating. Excess powder which has not stuck to an item can be swept up and reused. They produce almost no hazardous waste and do not harm the environment. The costs of running a large scale powder coating line are much lower than that of a large scale liquid painting line.
- Photo Credit www.cornabyrailing.com
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