Powder And Paint – The Different Ways Of Coating Materials

Zulu Mama Stools, Designed by Haldane Martin, Furniture Designer from Cape Town, South Africa. Martin says, “I have finally got around to creating a new product with the unique Southern African plastic weaving technique that I developed with local weavers for the Zulu Mama Cafe Chair. These simple three legged stools in various heights (450mm, 620mm, 820mm) are made from powder-coated 60% recycled rust proof stainless steel, and hand woven UV stable recycled polypropylene plastic.” Photo Courtesy: Micky Hoyle

There are lots of reasons why you might want to coat things like metal and wood. A layer of paint can give something a more attractive look, can protect it from the elements, and can make it more durable.

In manufacturing, there tend to be two main ways that things are coated – with paint, or with powder. Both of these dry to a lasting, robust finish, but while paint is the thing most DIY people are most familiar with, powder tends to often be the better solution in many fields of engineering and product production. Here we take a look at the main differences between the use of wet paint and dry powder in coating metals and other materials.

What Is Powder Like as a Coating Agent?

Fractal set occasional tables made with powder coated steel and clear toughened glass – Photo Courtesy: Design Initiative

While you have probably painted things before, whether it was walls, models, your car or anything else, most people don’t have any real experience of using powder as a coating agent. This is because it is generally something done on production lines to coat metal, plastic and even MDF (medium density fibreboard). When powder is used, it is generally applied using electrostatic technologies, before heat is applied to cure it. This can form an incredibly tough skin, of the kind you might notice on things like bicycle frames, home appliances and tools.

How Does Powder Differ From Paint?

Ironing Board as a Bookshelf – Powder Coat it! Nina, the owner of Nina Hale Inc., Minneapolis, Minnesota, USA, took her ironing board to a powder coater to paint it red and now she is using it as a bookshelf in her dining room. Photo Courtesy: Nina Hale

Paint is kept in a liquid form using a solvent in which the filler, binder and pigments are held in suspension. As the solvent dries, the other agents are left behind, giving you a hard, dry, painted finish. Paint, depending on the kind used, is relatively durable, but it does have a lot of negatives compared to powder as a method of coating things that are built to last.

• For one thing, when paint is used there is usually some waste as over spray cannot be reclaimed and reused. With powder, the over spray can be caught and used again, so the usage of the actual coating product tends to be close to 100%.
• Powder coating can also create a much thicker finish in one coat than paint without it sagging, blistering or running, leaving you with a tougher coating without risking the appearance of the thing that is being coated.
• It is also generally more cost effective on a manufacturing line to use powder than liquid paint coatings on metals and other materials. This is partly because of the lack of wastage, but the technologies involved and the products used are also, on the whole, cheaper.
• Powder also tends to offer a more uniform finish, which is less likely to get chipped or scratched. As items come off of a production line, there will usually be less difference between items that are supposed to look the same when a powder is used rather than a paint to coat or decorate them.

These are some of the main reasons why a lot of the things that you use in your home or outdoors that you may have assumed were coloured and coated using a conventional paint, were actually electrostatically coated using a powder instead!

Laura Harris, an engineer by profession, uses guest posting to share her knowledge and opinions about general engineering. Her day job is at TRJ Engineering, providers of powder coating services in Melbourne.