Introduction
E-coating, also known as Electrophoretic Painting, Electrocoating, or Electropainting, is a high-tech process that has been developed over the past fifty years. A specialized version of this technology, the Jingtu process, has been developed over the last 10 years.
The E-coating process was originally created to apply anti-corrosive coatings to steel car bodies. Today, E-coating technologies such as the Jingtu process are used to coat a wide variety of consumer goods, including hardware, jewelry, eyeglass frames, giftware, and many other items.
Customers appreciate E-coating's ability to handle high production volumes of parts with a unique combination of decoration and protection. The material utilization rate is close to 100%. This high production efficiency, combined with superior quality, results in lower unit costs.
How E-Coating Works
In the E-coating process, coating materials (such as resins, pigments, additives, etc.) are dispersed in water and held in a bath. The parts to be coated are immersed in the solution, and an electrical current is passed through the bath, with the parts serving as electrodes.
The electrical activity around the surface of the parts causes the resin that comes into contact with it to become insoluble in water. This results in a layer of resin (including any pigments and additives present) adhering to the surface of the parts. The coated parts are then removed from the bath and typically cured by baking in an oven to harden and make the coating durable.
Advantages of the Electrocoating Process
1. Immersion Process:
All surfaces in contact with the solution are coated. This means that even the most complex shapes can be fully coated. Parts can be more densely packed on racks to increase production rates.
2. Electrical Deposition Method:
The application of electricity causes the resins and other ingredients to deposit onto the surface of the parts. By controlling the electrical current, the thickness of the coating can be consistently and predictably applied. This is crucial when "tinted" coatings are required—such as brass or gold colors on bright nickel or zamak. Consistent color effects depend on consistent thickness.
3. Water-Based Process:
There are no flammability issues during application, and there is no need to dry parts after water-based cleaning or pretreatment processes. Using Ultrafiltration technology, rinse water can be extracted from the bath and recycled, returning nearly 100% of the "drag-out" back into the bath. This maximizes material usage and minimizes costs.
Comparing E-Coating with Solvent-Based Spraying and Powder Coating
| Solvent-Based Spray | E-Coat |
| Overspray is wasted | No overspray problem |
| Rack or support is coated | Insulated racks are not coated |
| Complete coverage is difficult | Complete coverage is characteristic |
| Consistent thickness is difficult | Consistent thickness is characteristic |
| Flammable during application | No flammability problem |
| Parts must be dry | Parts can be dry or wet |
| Powder Coat | E-Coat |
| Overspray is difficult to reclaim | No overspray problem |
| Rack or support is coated | Insulated racks are not coated |
| Very wide thickness distribution | Controlled, consistent thickness |
| Parts must be dry | Parts can be dry or wet |
From this, it can be seen that using spray techniques to apply finishes that can be achieved by E-coating will result in inferior coverage and inconsistent thickness. Additionally, there will be more material usage and wastage. Also, surface preparation before spraying is less versatile and may require more energy due to the drying process.
Furthermore, the following comparison illustrates the higher productivity of the E-coating process. The key question is, “How many parts can be coated for every 1 kilogram of paint?” This example is based on a standard part with a surface area of 15.5 square inches, with a minimum thickness requirement of 12 microns. E-coating delivers this within the range of 12–13 microns. High-quality spray paints need to apply 12–18 microns to be sure of maintaining a 12-micron minimum. Powder coating typically cannot go below 30 microns and works within the 30–60 micron range.
Note that in this example, the supply solids for both E-coat and spray paint are the same—50%.
The lower productivity of liquid and powder spray processes is attributed to their higher average thickness and overspray losses, including coating the racks. This shows that E-coating technology provides the highest quality finish in the most cost-effective way.
| System | Average Thickness | Number of Parts Coated |
| E-coat | 12.5 microns | 3600 |
| Spray paint | 15 microns | 2250 |
| Clear powder coat | 45 microns | 1200 |
Summary
Jingtu's E-coat systems offer a wide range of lacquer and paint finishes, combining cutting-edge performance with decorative effects, many of which cannot be achieved through spray application.
For modern-day applications, E-coating technology offers a coating process with minimal environmental impact:
- Less material and energy usage than both liquid spray and powder coating
- Lower volatile organic compound (VOC) emissions compared to solvent-based spraying
- Minimal liquid waste, thanks to the closed-loop Ultrafiltration reclamation process
E-coating exemplifies the application of modern technology to optimize a process in depth, providing a high-tech, environmentally friendly coating that is accessible to all users, both OEMs and job-coaters.