If you’re hoping to make your property stand out, from a business perspective or simply because you’re after something a little more unique, there are many surfaces including facades and interior doors, that can be utilised in a range of ways in order to make this happen. When it comes to commercial spraying services, cladding along with interior surfaces can be completely transformed using various different methods of on site spraying.

A particular technique that is becoming increasingly sought after is powder coating galvanised steel, as it not only provides an attractive aesthetic but it also substantially reinforces the substrate. Before deciding whether this could be a good option for your property, take a look at the different things you’ll need to consider before going ahead with this particular coating.

What To Know About Powder Coating Galvanised Steel

It’s important to find technicians who not only have a lot of experience in this kind of coating but also understand the problems that can occur and how to rectify them effectively. Before we explain the process further, we’ve broken it down a little, so our customers and readers can fully understand the technique and decide if it’s something that would be appropriate for their building.

zinc hot dip galvanizing process

What Is Galvanized Steel?

Put simply, galvanising is the process in which steel is covered in a protective layer of zinc, which is most commonly done through a hot dip technique. The steel substrate is submerged in a molten solution of zinc in order to effectively cover the entire surface. There are various benefits to galvanising steel, including its sustainable properties and durability; take a look at this article from the Galvanisers Association for a full explanation of why steel must always be galvanised. If any of your property has steel surfaces, applying a powder coating to them could be a great option for all of these reasons.

What Are Powder Coatings?

The main difference between a regular liquid and powder coating is the finish that it creates. Once a powder coating is applied, it is cured under intense heat, which in turn creates another skin type layer to the substrate, adding an extra form of protection. Powder coatings produce a seamless finish with the added benefit of protection against external elements – often keeping surfaces rust free for periods of up to 50 years! Powder coatings are generally applied to metals, including steel or iron, making galvanised steel the perfect candidate. Combining a galvanised substrate with the powder technique creates a duplex coating, helping to maximise the lifespan of a building’s structure.

galvanized steel pipes

How To Prepare Galvanised Steel For A Powder Coating

There are a few rules to follow when preparing galvanised steel, which is why employing experienced technicians is an absolute must. To prepare the substrate effectively, the following stages must be followed:

  • Any damage or defects to the galvanised steel should be removed or rectified before the powder coating is applied, which should be done within 12 hours of galvanisation for best results.
  • The surface must be thoroughly cleaned and dry before the coating is applied. Take care not to use highly acidic solutions to clean the steel, as this can result in stripping the zinc from the surface.
  • In order for the steel to take the coating effectively, the surface must be profiled and free of any protrusions before applying the powder. This can be done via a range of methods, but again, care must be taken not to remove the zinc layer from the steel’s surface.
  • The substrate should be primed before applying the powder coating to ensure optimum adherence. An example of this could be the use of a phosphate treatment, applied to the steel for a few minutes before being washed away and left to dry, ready for the powder coating.

For an in-depth look on how to thoroughly prepare galvanised steel for powder coatings, take a look at this detailed guide from Wagner Companies.

What Problems Might Occur?

While powder coatings are regularly applied to galvanised substrates, there are still several issues that can occur if it is not done correctly. Research is ongoing into the three main problems that are associated with this technique, so they have improved since the method was first developed in the 1960s, but nevertheless, continue to be an issue.

  • Pinholing – This problem refers to the minute gas bubbles that form during the curing period once the coating has been applied. They look unattractive and can also create exposed areas on the surface that are not as durable.
  • Poor Adhesion – During the hot-dip galvanising process that we mentioned earlier, the last stage involves the substrate being quenched in water to allow easier handling. This, unfortunately, interferes with the phosphate priming treatment that needs to take place before the powder coating is applied – making it essentially ineffective. In order for the priming treatment to work, the quenching process must be avoided for any galvanised surfaces that are also going to be powder coated. This ensures that the phosphate treatment and ultimately, the finished powder coating, adheres correctly to the steel substrate.
  • Incomplete Curing – As mentioned, once the powder coating is applied, it needs to be sufficiently cured under the correct level of heat. Enough curing time needs to be allowed for the coating to be fully effective.

For a much more in-depth look at the science behind these common problems, take a look at Powder Coating Online for extensive explanations.

powder coated steel rods

Interested In This Specialist Coating?

Here at Just Spray, we have a range of specialist coatings, which we regularly carry out through our cladding spraying services as well as inside properties, on various surfaces. We recently carried out a project in Brighton in which we were enlisted by a company to rectify a previous powder coating completed by a different spraying specialist. Unfortunately, the galvanised steel coating had been applied incorrectly, which meant that it quickly began to deteriorate. For more information on the above project, along with our application process and photos, head over to our case study page!

If powder coatings are something that you are interested in, don’t hesitate to give the team a call and we’d be more than happy to advise!

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