It’s a beautiful Saturday morning, and you decide to work on your car, tweaking a few things before your daughter’s wedding scheduled for early afternoon.
As luck would have it, you walk into a situation my dad always called a five-minute job that lasts all day. You find yourself sitting on the garage floor, covered in grease, frustrated beyond belief. You take a moment to look at your watch to discover that you have 45 minutes to prepare for the most important day in your daughter’s life!
Quick question: would you leave the garage, change into your tuxedo, then leave for the wedding? Or would you take a shower, clean up, then leave?
Simple question, right?
Remember as you read this: you are an OEM manufacturing a high-visibility vehicle. After your metal fabricator welds and forms your components, it’s time for a powder coat.
Would you want your high visibility component to move from fabrication directly to paint with no steps in between? It’s like tossing your tux after working on your car without a shower.
As they say, that dog don’t hunt!
Professional powder coating companies depend on a well-prepared metal surface. Pre-treatment is a prerequisite for powder coating of any metal because it’s dirty and covered in oil and dirt, preventing good adhesion. Metal coated with dirt or oil prevents perfect coating of the surfaces.
Good pre-treatment is the perfect preparation for powder coating. You cannot get the best result from your coating without good pre-treatment. Many options for pre-treatment work well before powder coating metal.
Choosing the best one can be confusing, with many options and factors to consider. In this blog post, we’ll walk you through the three main types of pre-treatment and tell you when each is most useful.
We know it’s overwhelming to read about all these treatments, but we want to ensure you have all the information you need to choose the right process for your business.
Choose the Best Pre-Treatment Method
Many factors to consider when choosing a pre-treatment method include ease of use, costs, environmental factors, the number of parts, and more. We’ll walk you through each of these and help you assess the best method. Consider these factors when choosing a pre-treatment method:
- Availability: Where are you sourcing your parts from? What facilities are pre-treatment processes commonly used in? If you’re sourcing parts from abroad, there is limited availability.
- Ease of Use: What level of expertise is required to use the process? If it’s difficult to use, it will take longer to prepare your parts and cost more.
- Environmental Factors: How does the process affect your surroundings? What kinds of chemicals do you use? Are there any precautions or safety measures you need to take?
- Quantity of Parts: Some pre-treatment methods are better suited to larger quantities of parts than others.
- Type of Parts: Different pre-treatment methods are best for different metals.
Sandblasting
Sandblasting is blasting parts with abrasive grains of sand under high pressure, a quick and effective way to remove rust, dirt, and other impurities from metal parts. Sandblasting smooths out the surface of a part before coating. When used for pre-treatment, sandblasting works best for small batches of parts but is not as well-suited for large batches. It’s important to note that sandblasting leaves light dust on parts, requiring a shower before coating. Sandblasting is an excellent choice for pre-treatment because it’s effective and relatively inexpensive.
Chemical Processes
Pre-treatment uses many chemical processes, including alkaline, acid, chemical stripping, and immersion. These chemical processes all have a similar goal: to remove impurities and contaminants and prepare a part for coating. These chemical processes are best for small batches of parts (10-15 parts at a time) but used for larger batches if the equipment is large enough. They have a high upfront cost and a longer lead time than other processes. They are generally better for harder metals in the auto and aerospace industries.
Electrostatic Painting
This process involves spraying electrostatic paint onto a part. The paint has positively charged particles attracted to negatively charged metal parts, binding them. When the paint dries, it has a strong grip on the part, effectively coating the surface.
While effective, it does not suit electrostatic painting to many metals. Some metals are too conductive to be coated effectively with electrostatic painting. Test the suitability of the paint on the part beforehand to ensure it works.
| Factor | Sandblasting | Chemical Process | Electrostatic Painting |
|---|---|---|---|
| Cleaning Effectiveness | Good | Excellent | Good |
| Surface Finish | Rough | Smooth | Smooth |
| Cost | Low equipment cost, but high media cost | High chemical cost | High equipment cost |
| Waste Produced | Low | Moderate | Low |
| Environmental Impact | Moderate | High | Low |
| Safety | Moderate (requires respiratory protection and other safety gear) | High (requires chemical handling and disposal precautions) | Moderate (requires proper ventilation and grounding) |
| Versatility | Good for small batch jobs and most materials | Ideal for hard metals like steel and aluminum | Only works on conductive metals |
Drying and Curing Processes
Pre-treatment needs multiple drying and curing processes, including hot air drying, oven curing, and ultraviolet and infrared curing. These processes evaporate residual moisture, chemicals, and oils from a part of high heat and leave behind a clean, dry surface. These processes are best because drying and curing processes require a high temperature, often used for small batches of items. Some processes, like oven curing, can be used for larger batches but take longer than other methods.
In Sum
Pre-treatment is a crucial part of the powder coating process. Without it, your final coating will be clumpy, uneven, and look terrible. The right pre-treatment method ensures that someone perfectly prepared your part for coating. There are many types of pre-treatments, each with distinct advantages and disadvantages. You can choose the best pre-treatment method based on the required number of parts, type, and level of expertise.
Now, another quick question: what in the cornbread hell made you decide to work on your car the morning of your daughter’s wedding!?