What is E-Coat?

So, what is E-Coating?

Introduction

E-coating – also known as Electrophoretic Painting, Electrocoating, Electropainting etc. – is a high-tech process that has been developed over the last fifty years. A specialist form of this technology – the CLEARCLAD process – has been developed over the last 25 years.

The E-coat process was originally developed for applying an anti-corrosive coating over steel car bodies. E-coats such as the CLEARCLAD processes are used for coating a wide range of consumer goods including hardware, jewellery, eyeglass frames, giftware and many other items.

Users recognize E-coat’s ability to paint high production volumes of parts with a unique combination of decoration and protection. Material utilization is close to 100%. This high production efficiency coupled with advanced quality results in lower unit costs.

How E-coating works

The coating materials (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 using the parts as an electrode.

Electrical activity around the surface of the parts makes the resin directly in contact become insoluble in water. This causes a layer of resin – including any pigments and additives present – to adhere to the surface of the parts. The coated parts can then be removed from the bath and the coating is normally cured by baking in an oven to make it hard and durable.

Advantages of the Electropainting Process

Immersion process: All of the surfaces in contact with the solution are coated. This means that even the most complicated shapes can be completely coated. Parts can be more densely packed on the rack to increase production rate.

Electrical deposition method: The application of electricity causes the resins and other ingredients to deposit onto the parts’ surface. Controlling the electrical current enables a predictable and consistent thickness of coating to be applied. This is essential if “tinted” coatings are required – for example “brass” or “gold” colors over bright nickel or zamak. Consistent color effect demands consistent thickness.

Water based process: There are no flammability problems during application. Also, 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 itself and used to recycle nearly 100% of 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

  • Overspray is wasted
  • Rack or support is coated
  • Complete coverage difficult
  • Consistent thickness difficult
  • Flammable during application
  • Parts must be dry

E-coat

  • No overspray problem
  • Insulated racks are not coated
  • Complete coverage characteristic
  • Consistent thickness characteristic
  • No flammability problem
  • Parts can be dry or wet

Powder Coat

  • Overspray difficult to reclaim
  • Rack or support is coated
  • Very wide thickness distribution
  • Parts must be dry

E-coat

  • No overspray problem
  • Insulated racks are not coated
  • Controlled, consistent thickness
  • Parts can be dry or wet

From this it can be seen that using spray techniques to apply finishes that can be achieved using E-coat processing will give inferior results in terms of coverage and consistency of thickness. This is in addition to greater material usage and wastage. Also, surface preparation prior to spraying is less versatile and can require more energy because of the need to dry.

Further, the following comparison illustrates the higher productivity of the E-coat process. The 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. The minimum thickness requirement is 12 microns. E-coating is able to deliver this within the range of 12 – 13 microns. Good quality spray paints need to apply 12 – 18 microns to be certain of maintaining a 12 micron minimum. Powder coating cannot deliver much less than 30 microns and will normally work within a 30 – 60 micron range.

System Average Thickness Number of Parts Coated
E-coat 12.5 microns 3600
Spray paint 15 microns 2250
Clear powder coat 45 microns 1200

Note that in this example the supply solids of the E-coat and spray paint are the same – i.e. 50%.

The lower productivity of the liquid and powder spray processes is due to their higher average thickness and over-spray losses including coating the rack. This shows that the E-coat technology delivers the highest quality finishing in the most cost effective way.

Summary

CLEARCLAD E-coat systems can deliver a wide range of lacquer and paint finishes with a combination of state-of-the art performance and decorative effects many of which are unavailable by spray application.

And finally, for the modern age, E-coating technology delivers a coating process with minimal environmental impact:

  • Less material and energy usage than both liquid spray and powder coating.
  • Lower volatile organic content (VOC) emissions than solvent based spraying.
  • Minimal liquid waste using closed loop Ultrafiltration reclaim process.

E-coating is an excellent example of the application of modern technology to optimize a process in depth. A high-tech, environmentally friendly coating made accessible to all users, both OEM and job-coaters.