E-coating, also known as Electrophoretic Painting, is a sophisticated process used to apply a semi-transparent, anti-corrosive coating to certain metals. However, unlike other coating methods, e-coating doesn’t give the material an enamel-looking finish.
Even though this technique can be used on various metal objects such as vehicles and furniture, it has especially gained popularity among jewelers. It allows them to use unconventional colors in their designs without making the pieces lose their metallic shine.
E-coating is basically a combination of plating and painting. During this process, the metal is soaked in a water-based paint emulsion. An electric current is passed through the solution, which usually contains pigments and resins. This causes a chemical reaction that results in the adhesion of the paint to the surface of the metal.
Once the metal is removed from the mix, the coating is hardened by exposing it to high temperatures for a certain amount of time. The metal is then polished to create a smooth finish.
Why Use E-Coating?
There are many advantages of e-coating. Below are just a few reasons why this technique has become a favorite among artisans such as jewelers:
- Other than gold-plating, which can only be applied in white or rose colors, e-coating offers you an unlimited range of colors.
- The thickness of the layer added through e-coating is consistent throughout the entire piece. This is especially useful for metal pieces that are more complex, such as intricate jewelry designs.
- E-coating doesn’t change the chemical composition of the metal that it’s applied to.
- The e-coating process requires less material and energy than other coating processes, making it more environmentally friendly. With ultra-filtration technology, water can be recycled by extracting it from the mix. This water can then be used for rinsing to minimize costs and maximize material usage.
- Because the items are immersed in a water-based solution, the risk of flammability is minimized.
Before You Start E-coating
Below are a few things you should consider before using the e-coating technique:
The type of metal:
E-coating is not suitable for costume jewelry as it can cause the materials to burn. It’s also more complicated to e-coat atypical metals such as titanium and niobium, as it’s more difficult to make the color stick. Therefore, it’s best to use this coating method on standard metals such as silver, gold, and platinum.
If the item you want to coat contains design components such as glass stones or enamel, they may be ruined during the e-coating process.
Any color applied through the e-coating process will be very difficult to remove. Therefore, you should pick your color carefully to avoid regretting it afterwards.
Once you’ve taken these factors into consideration, you can start preparing your item for the e-coating process.
The 6-Step Process for Getting the Most Benefits
- Polish the surface until smooth
Regardless of what type of metal the item is made of, it should first be polished to get rid of any irregularities on the surface. This will also help remove tough dirt such as any grease or grime. A rough texture will result in an uneven coating.
- Clean the surface
Polishing will result in metal filings and other residue that may prevent the adhesion of the e-coat. Therefore, the surface needs to be cleaned properly before going any further. The type of cleaning solution used will vary based on the type of metal. For iron and steel, an inorganic phosphate solution is usually preferred. For silver and gold, alkaline cleaners are very common.
An ultrasonic cleaner is the perfect tool for this job. This tank uses mechanical vibrations to create soundwaves in water or cleaning solution. When metal objects are placed in the solution, the bubbles created by the soundwaves will clean even those hard-to-reach places.
Once the item is completely free of all dirt and scratches, it should be rinsed in distilled water and neutralizer. This will help remove any residue caused by the chemicals used in the cleaning procedure. This step should be repeated a few times to ensure that the item is free from any impurities. That way, you’ll have a better chance for successful adhesion during the e-coating process.
- Dip in a wetting agent
To ensure that no bubbles adhere to the item before submerging it in the e-coating solution, some manufacturers dip it in a wetting agent (also called a leveling agent). A wetting agent will lower the surface tension of the coating solution to ensure that it adheres to the metal’s surface more cohesively. This decreases the probability of any paint defects on the finished item.
- Submerge in e-coating solution
When you’re completely sure that the item has been thoroughly cleaned, and you’ve applied your wetting agent, it’s time to submerge it in the e-coating solution. The chemicals used in the solution will depend on a few things, such as the type of metal that the item is made of.
Make sure that the entire item is submerged. This will ensure an even coating on every inch of the item, including those crevices that are difficult to reach. Electrical currents running through the solution will result in a chemical reaction that fuses the coating to the metal surface.
- Cure the coating
Once the item is removed from the e-coating solution, it’s baked in a kiln or oven. This results in the hardening of the coating to ensure durability, and also creates a glossy finish. The temperature at which the item should be cured will depend on the chemistry of the e-coating solution that was used. Rushing this step may affect the quality of your e-coat, so it’s best to take your time with this one.
E-coating has changed the fashion industry by allowing artisans to create durable jewelry in a variety of colors. Because the e-coat solution is semi-transparent, the metal underneath can still be showcased. Therefore, e-coating is a favorite among jewelry makers who don’t want their pieces to have a dull, matte finish. What’s more, e-coating is eco-friendlier than ther coating methods. However, it’s a high-tech process that’s best left to the professionals.