How to Prepare a Surface for Powder Coating

Preparation is the name of the game for most automotive processes and applications, but for something a little more complicated like powder coating, it can be especially crucial for achieving the desired finish. If your preparation isn’t up to standard, you could end up leaving the surface vulnerable to the same issues the coating is intended to prevent.

Here, we’ll be giving you an overview of what powder coating is and which surfaces it can be used on before delving into the best method for preparing a surface for this process.

What is powder coating?

Essentially, powder coating is a process used to boost the durability of a surface. Unlike standard paint, the powder coating isn’t porous, and this means it’s better at preventing water, salts or debris from penetrating the surface and causing rust or corrosion. This can be used across various industries, including industrial, manufacturing and automotive, and is most commonly used to protect tools, work surfaces and metal surfaces on vehicles.

So, how does powder coating work? A dry polymer-based powder is mixed with curing additives, levelling agents, flow modifiers, pigments and resin. This concoction bonds to an electrostatically charged surface which can then be heat-cured in a kiln or oven. Under high temperatures, the powder melts and coats the surface evenly, eventually hardening and becoming smooth as it cools off.

Which types of surfaces can be powder coated?

Many different types of surfaces can be powder coated, including metal, concrete, steel and some plastics. However, due to the high temperatures used during the curing process, it’s not possible to powder coat any surface that might melt easily. This means many rubbers and plastics can’t have this type of coating, along with other materials like wood.

 Why is surface prep important?

Surface preparation couldn’t be more important for ensuring the powder coating adheres well. But this isn’t the only reason why you should focus your efforts on surface preparation. If you neglect this step, it can have a big impact on your finish and lead to cosmetic imperfections such as bubbling, bumps and peeling. In some cases, an uneven or bubbling finish can lead to corrosion, which is usually the exact issue that the coating is intended to prevent. Not only can this be time-consuming to correct, but it can also be a waste of your resources since you’ll need to completely remove it, re-do your surface preparation and start the powder coating process again.

Making sure you properly prepare the surface before beginning the powder coating process is the best way to keep corrosion and rust at bay.

How to prepare a surface for powder coating

Knowing how to prepare the surface you’ll be powder coating is essential. Here, we’ll take you through the step-by-step method you should use to achieve the best results.

1. Disassemble any necessary parts 

If the surface you want to powder coat is in multiple parts or is attached to other surfaces that won’t be going through this process, you’ll need to disassemble this first. For instance, when you’re powder coating alloy wheels, the first step would be to remove these from the vehicle. This might require loosening screws or fastenings, so be sure to have the necessary tools to hand.

2. Clean the surface

 Any contaminants such as dirt or oil must be removed. The easiest way to do this is to take a clean sponge, warm water and a specialist cleaning solution suitable for the surface you’re working on and thoroughly wash it. 

3. Pre-bake the surface 

For porous surfaces like aluminium and cast iron, it’s a good idea to pre-bake to remove any oils that might have been absorbed by the surface during the manufacturing process. If these oils are left on the surface, they can outgas the powder coat bake and cause bubbles or bumps to appear in the final finish.

4. Sanding/sandblasting 

Depending on the size of the surface, you’ll also need to sand or sandblast the surface. Sanding by hand will be best for smaller surfaces, while sandblasting is a more industrial technique ideal for larger surfaces. Whichever you choose to do, this step is crucial for ensuring the surface texture is primed and ready for the powder coating to adhere properly while also removing any imperfections such as rust or corrosion.

5. Surface masking

The final step is masking off the surface to ensure you protect any areas that you don’t want to powder coat. When you’re doing this, you should ensure that the surface stays contaminant-free and that the masking solutions you select can withstand the powder coating process which we can help with below.

JTAPE powder coating tapes

Looking for high-strength, durable car masking tapes that can easily withstand the high temperatures used during the powder coating process? Below, we’re offering our top masking solutions from the JTAPE range which can help you get the job done with simplicity and efficiency.

Green High Temperature Polyester Film Tape

With temperature resistance up to 220°C/428°F for up to 30 minutes, this polyester film tape with silicone-based adhesive is ideal for protecting surfaces during the powder coating process. Offering reliability, strength and increased thickness, this masking tape can remain durable which means you won’t need to worry about any areas of the surface becoming damaged during the process.  

Green High Temperature Polyester Film Discs

When working on alloy wheel powder coating, our Green High Temperature Polyester Film Discs are the ideal masking solution. These discs are specifically designed to cover the rear hub of alloys while offering excellent temperature resistance of up to 220°C.

Blue High Temperature Polyester Film Tape

Similar to our green version, JTAPE Blue High Temperature Polyester Film Tape offers an innovative solution to mask off areas of the surface that you don’t want to powder coat. Offering the same temperature resistance, strength and durability, this thinner version of the polyester film tape is also flexible and easily conforms around bends or corners.

Proper preparation is the key to achieving an excellent finish when powder coating a surface. Using the tips and information from this blog, you should be ready to apply powder coating over a properly prepared surface and understand why this is necessary.

For more advice and insights into the automotive industry, check out our JTAPE blog.