Pretreatment is an essential part of the powder coating process. Without proper pretreatment, your product does not have corrosion protection which can lead to visual degradation and structural failure. Pretreatment is the processes through which a surface is cleaned and prepared to be coated. This process creates a surface that the coating can adhere to, whether the coating is liquid or powder. Plus, pretreatments heighten the performance value of a coating, increasing its life and helping to prevent corrosion.
At Pinnacle Powder Coating, we always strive for the best with our coatings and we know how important applying pretreatment is to a well-prepared substrate is. We apply pretreatment to all products, most often using a spray and wand system, this is one way we guarantee quality products.
Pretreatment chemicals can be applied in a number of ways:
Immersion Systems: Used for parts with many nooks and crannies, but have a large footprint
Spray Systems: Best for simple parts and usually have a smaller footprint than immersion
Manual Spray Wand Systems: Suggested for a small footprint
Cleaner/Coaters: This one-step coating which decreases the number of stages
There are many different ways of pretreating and various types of pretreatment available. It depends on the product you’re coating and its size. Now that you know the what and how, let’s discuss the rest of the pretreatment process. Despite the application process, there are three main steps in the pretreatment process: cleaning, conversion coating, and post-treatment.
Step One: Cleaning
Cleaning is what every stage after this relies on, including successful powder application. Simply put, the less contamination there is on a surface before it is treated, the better the conversion coating step, post-treatment, and inevitably the powder coating will perform. Pinnacle goes a step further and heats the cleaning solution which causes the cleaning agent to work better.
Step Two: Conversion Coating
The surface of the metal being chemically converted to a completely different substance that has increased corrosion resistance and a greater surface area which will promote enhanced paint adhesion. Most pretreatments are acidic in nature. The acidic solution first etches the metal surface and then deposits a substance which is chemically bonded to metal substrate. Popular conversion coatings include, Zinc Phosphates, Nanoceramics, Iron Phosphates, and Chromes/Chromates.
Step Three: Post-Treatment
A post-treatment is applied to seal in the conversion coating and provide improved corrosion resistance and paint adhesion. It seals any voids in the conversion coating allowing for stronger performance with corrosion resistance. At this stage, an additional rinse without chlorides or fluorides in the water further improve quality.
For further information about powder coating pretreatment, please contact our team at 419-660-9883.
Resources for this article include an array of resources including our own experts for other literature we recommend Powder Coated Tough Publication and Henkel Functional Coating News to be most useful.
