Eliminating the ‘Orange Peel’ Effect When Applying Powder Coating

When applying powder coating to objects, it’s important to use the correct method to avoid the dreaded ‘orange peel’ effect that can result from poor application. Not only does this effect look bad, it can lead to rusting or oxidisation of the object in the orange peel areas, because the air will still be able to come into contact with the metal.

So what causes the orange peel effect, and how can you avoid it?

The ‘orange peel’ effect

An orange peel effect after curing powder coating usually occurs because the coating was applied too thinly or too heavily. Too much powder also results in the object being more prone to damage by chipping.

How to avoid the orange peel effect

While applying powder coating, it’s important to monitor the application to make sure that the powder is applied evenly. One effective way of doing this is to use an LED light on the part while you are spraying on the powder. As soon as you can no longer see bare metal highlighted by the light, you know that you have applied the right amount of powder. Obviously, this method relies purely on eye for accuracy and can still lead to imperfections in the final finish.

A more reliable method is to use a mil thickness gauge that works on ferrous and non-ferrous metals. Once the powder coating has been cured in the oven, you can use the gauge to measure the precise thickness of the coating.

Before starting a project, cure a test piece on the oven and measure the coating with the thickness gauge. The ideal thickness should be 2.0 to 3.0 mils for a perfectly even finish. Once you’re happy with the finish on the test piece, you will know how much powder to apply to the project article to avoid the orange peel effect.  

Perfect powder coating technique

For an orange peel-free finish, apply the right amount of powder to the object based on the test piece you created earlier, concentrating on achieving an even coat. Place the object into the oven for curing, and set the oven temperature to 1180C.

Keep an eye on the object and remove it as soon as the powder coating appears wet. While the object is still warm, spray on a very fine coat of powder, so that you can no longer see a reflection in the surface of the object. Place the object back into the oven, and allow it to cure fully.

Author: Milton Rogers

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