Powder coating is commonly applied to many metals since it enhances the metal’s corrosion resistance. Can it be applied to stainless steel, though? And, is it necessary since stainless steel is already corrosion resistant?
Yes, stainless steel can be powder coated, given that the metal is prepared adequately. The workpiece must undergo thorough surface cleaning, passivation and sand blasting before your do the powder coating. Once completed curing must be done in oven for best results. The correct powder coating products and procedures should also be adhered to, ensuring success.
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Why Would You Powder Coat Stainless Steel?
While stainless steel is highly corrosion-resistant, it’s not corrosion-proof. Applications notorious for taxing stainless steel’s corrosion resistance include environments with prolonged exposure to corrosive materials, such as seawater, sewerage applications. Also high on the list are chemical plants and roads where de-icing chemicals are applied in winter. Other factors that lead to corrosion in stainless steel are nicks and bumps on the metal’s surface, as would be the case with bollards, railings, and bike racks.
These are prime applications for powder coating stainless steel since the polymer used to coat the metal is corrosion-resistant.
Sometimes, an application calls for the resilience of stainless steel, but in a different color or with a different surface finish. Here, powder coating could again be the answer since the polymers can come in any color imaginable.
How Does Powder Coating Work?
Powder coating is the process during which metals are coated with a thin, protective polymer layer. When done correctly, you get a product with the metal’s strength and elasticity, paired with a surface finish of the desired color and texture, as well as being corrosion resistant.
The process’s details vary slightly, depending on the metal chosen. Here are the steps followed to powder coat stainless steel:
Surface Cleaning
Removing oil and dirt is essential in successful powder coating. Impurities on the metal’s surface could interfere with the polymer’s bond to the metal, so the metal gets a thorough physical cleaning.
Passivating
Also known as pickling, passivating is when metals are carefully treated with corrosive chemicals to remove a thin surface layer. If this preparation step isn’t done with extreme caution, the harsh chemicals used could cause corrosion. The aim here is to remove areas where the surface distribution of alloying elements was disturbed, such as near welds or where the metal is scratched or dented.
Blasting
Sandblasting removes any residual impurities missed by the previous two steps. Once blasting is complete, the part is carefully and thoroughly cleaned again, removing any blasting residue.
Primer and Powder Coat
Primer and powder coating layers are applied using an electrostatic charge. These layers are very thin but highly resilient. Applying them using electrostatic charge instead of paint ensures that there are no pinholes on the finished surface.
Curing
Once applied, the powder coating is oven cured to ensure that the resin hardens to the desired degree. Adequate curing ensures that the finished product can withstand corrosion, abrasion, and scratches.
Is Stainless Steel Easy to Powder Coat?
Stainless steel is relatively easy to powder coat. You could even do this at home as a DIY project for some applications, provided that you have the correct equipment available. This is a precise process, though, so powder coating projects aren’t recommended for inexperienced DIY enthusiasts.
For applications where high wear resistance and specific chemical attributes are desired, such as a high-wearing antibacterial finish, it’s best to leave the powder coating to the professionals.
Benefits of Powder Coating Stainless Steel
Powder coating stainless steel has many benefits, the most prominent being that it is unlikely to rust or corrode. Other benefits include greater resistance to scratching and chipping. Powder-coated stainless steel is also less likely to fade and can be prepared in any color imaginable. This broadens the aesthetic horizons of stainless steel applications.
With technological advances, powder coating offers new benefits as well: it can be antibacterial, antifungal, anti-fingerprint, and self-cleaning too.
Since the powder coat is a polymer layer, it is flexible and will thus not crack when the metal flexes under load.
Does Powder Coated Stainless-Steel Rust?
When the powder coating on stainless steel remains intact, the metal will not rust. This is due to the protection offered by the powder coating: corrosive elements can’t reach the metal, and therefore it won’t rust.
When this corrosion-resistant polymer layer is damaged, a weak spot forms, allowing corrosive elements access to the metal. These elements, such as seawater or harsh chemicals, enter the protective environment underneath the powder coating. They are now free to wreak havoc on the otherwise protected metal. Underneath the powder coating, there is nothing to wash away the harmful chemicals. Thus they will leisurely eat away at the metal until they are spent or replaced by other chemicals that made it into this environment in the same manner.
In short: if the powder coating is done correctly and remains intact, stainless steel will not rust. If, however, the powder coating gets damaged, the metal will probably rust faster than uncoated metal.