What are Powder Coatings

What are Powder Coatings?

There are two principle technologies that are the backbone of the coatings industry.

  • Liquid paint technology (wet) that was first used by cavemen and has been used industrially for more than 200 years
  • Powder coating technology (dry) that has been used for the last 40 years.

In the simplest terms powder coating is paint which is made and supplied in a dry powder form. This contrasts with traditional paints that are liquids applied by brush or spray.

Powder coatings are available in different chemistries and systems to provide both decorative and protective finishes for a wide range of end uses.

Powder coatings are generally used for the painting of metal objects. However, newer technologies allow other materials such as MDF, glass and plastics to be coated.

The use of powder coatings has grown rapidly since their inception for a number of reasons. They provide excellent paint finishes and, because they do not contain solvent, they have minimal environmental impact.

So how are they used?

Powder coatings are supplied in boxes or bags and application is very simple.  The powder is applied to an object using an electrostatic spray gun.   Compressed air sucks the powder out its container and pushes it though pipes to the gun. At the nozzle of the gun is an electrode which gives the powder particles a positive charge.

Figure 1: Electrostatic Powder Spray Gun

The object being coated is grounded so the positive powder particles are attracted to it. When the object is completely covered it is put into an oven to be baked or cured. Whilst in the oven, the powder firstly melts and then goes through a chemical change to create a tough and complete paint layer.

Figure 2: Typical Lay out of a powder coating application plant

What can I apply powder to?

Powder coatings can be applied to almost any metal item that can withstand the typical curing conditions (180-200C for 10-20 minutes) and can fit in an industrial oven. Other substrates such as MDF, glass and plastic can also be coated.

When the appropriate powder formulation is selected a very wide range of items can be painted. This can vary from the body of a car right through to small components inside electric motors. Many objects around us in daily use are powder coated. Washing machines, computers, radiators, metal window frames, alloy car wheels and furniture are just some examples.

As with any paint the mixture of ingredients can be adapted and adjusted to suit the final end use. Properties can include resistance to weather for exterior windows, scratch resistance for furniture and chemical resistance for car components.

As well as protective properties powder coatings also give excellent decorative appearance. Available in almost any colour there is also a very wide choice of surface finish and gloss levels.

The advantages of powder coatings over conventional paint

Powder coatings:

  • contain no solvent
  • emit no VOC’s (volatile organic compounds)can produce much thicker coatings without running or sagging
  • Powder which does not adhere to the part, called overspray, can be recycled and reused (no wastage)
  • production lines produce less hazardous waste than conventional liquid coatings