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Corrosion Prevention Methods: How to Identify Proper Paint Application Using Contrasting Paint Colours

Coating inspections can be a lengthy and sometimes tedious process that often presents many variables. Luckily, there are many types of corrosion prevention methods that make it easier for the inspector and can also streamline the problem identification process.

For example, contrasting colours on multiple coat systems is a great method of identifying proper film thickness and ensuring the proper generic type of coating has been used at each layer.

Using contrasting colours on multiple coat systems is both important on the back end when the system is complete and is done so that issues can easily be identified by the layer of the coat when there are investigations or failures.

What are contrasting colours for multiple coat systems? 


‘Contrasting colours’ simply means applying a different colour scheme, or off colours, to every coat of paint. For example, black on white or white on black so you can see the previous coat.

This type of corrosion prevention method is done to ensure that layer identification is easily made by the inspector when they are reviewing a failure. Contrasting colours make it easy to identify the different layers of coating starting from the substrate, IE concrete or galvanized steel working your way up to the topcoat.

An Industry Example


Currently, we’re working on a project with a two coat system and it’s laid out as white on white. There’s a lot of deficiencies, not to the fault of the applicator, but because it’s virtually impossible to see your spray patterns when you’re pulling a white urethane over top of a white epoxy. The only thing you really have to go on is the sheen and without an extremely bright light, it makes it really difficult to get a uniform finish.

On top of that, it makes it hard to see your overlap.


Types of Corrosion Prevention Methods: Why It’s Important to Use Contrasting Colours


With types of corrosion prevention methods, coating materials have a property called opacity (or hiding) and are often used to pinpoint the layer you’re on as well as hide the layer beneath it. Every coat, formulation and colour chosen has a different opacity to it. Opacity help to assist in your inspection and to notify the engineer or client, ensuring an accurate finish.

You don’t necessarily need a huge contrast in colours, but the contrast should be significant enough that the DFT of the next coat will hide the colour beneath it. A visual inspection should be able to notify and locate the areas of corrosion and make it easier for a compliance check.

Even if it’s off white and white, the smallest little additive of colour into a coating makes a huge difference and can end up saving time and money.


Using Contrasting Colours for Stripe Coating


Contrasting colours for stripe coating offer similar results and help to ensure that the stripe coat is being applied correctly. However, this method can end up being costly if the coating supplier provides two different colours and the coat doesn’t cover or hide the contrasting colour stripe coat.

So, what’s the solution?

To avoid a costly process or dispute with your coating manufacturer, when dealing with stripe coat make sure you verify with your coating manufacturer that the colours used do actually cover the minimum specified thickness. Make sure your specification addresses the visual component to override thickness in order to save money and ensure a proper finish of stripe coat.

Our Takeaway


There are many types of corrosion prevention methods and using contrasting colours is a method that not only can prevent corrosion, but also identify and correct corrosion quickly and safely.

It’s a method that we often recommend and a technique we use with our clients and the companies we work with to ensure compliancy, safety and cost-effectiveness.

If you are looking for more information on how to properly use contrasting colours, contact us today for a free consultation and quote.

Scott Menzies

Scott menzies

Owner, The Coating Inspector