Never Paint an E-Coat without Priming. Here’s Why

“There are several problems with painting directly over e-coated parts. Although OEM e-coat is an excellent corrosion protection coating (not sure about some of the aftermarket parts), e-coat contains no UV protection package. E-coat is generally epoxy based and unless completely shielded from UV rays, its surface can become unstable. Resulting in paint layer separation and peeling. Some of the newbies in our industry may not remember the early 90s, but many of us do. How many GM and Chrysler factory paint peelers did you repair in your professional career? These cars and trucks peeled for the same reason, UV exposure to the e-coated surface.” — Stefan Gesterkamp, autobodynews.com

“Most Original Equipment Manufacturer (OEM) parts come from the factory with a primer called e-coat. E-coat stands for Electro-deposition Coating. The part is dipped into a primer bath and the e-coat adheres to the part with the help of an electrical process. E-coat is a very durable and corrosion resistant coating so it should not be removed from the part. Most e-coat appears to be a glossy black coating.” PPG Refinish (and steps below)

  1. Review work order to ensure that all parts to be painted are present and repairs are understood.
  2. Inspect part for imperfections and damage. Determine what repairs should be made if any (follow all process documents for repairs made to the part)
  3. Clean entire part thoroughly with Wax & Grease Remover and/or waterborne cleaner and a clean towel. Dry thoroughly to ensure there is no leftover residue.
  4. To determine if E-coat is stable:
    Test by rubbing e-coat with thinner or urethane grade solvent on a clean towel. If coating wipes off or softens significantly, it must be removed by sanding. Apply approved bare metal primer to ALL exposed bare metal areas.
    If e-coat is stable, proceed to next step.
  5. Electrodeposition Primer must be thoroughly cleaned and may then be directly overcoated with Sealer in a wet-on-wet application without abrading.
    1. To remove minor defects – Lightly sand primer with a DA sander with 400 grit and an interface pad. Remove as little e-coat as possible.
    2. If preferred, on edges, body lines and recessed areas, use a hand scuff pad.
  6. Re-clean entire part thoroughly with Wax & Grease Remover and/or waterborne cleaner and a clean towel. Dry thoroughly. Tack off the dry part before Primer Sealer application.
  7. Primer Sealer must be applied to e-coat. Apply medium wet coat of primer sealer to entire part.

“Ecoat is used because it provides superior corrosion protection as it coats surfaces that are inaccessible by conventional means. Film thickness is uniform without any defects such as sags, runs or edge beads. Electrocoat is also very cost effective as it provides nearly 100% material utilization with good energy efficiency and a relatively low cost per square foot of applied coating.” Prospector Knowledge Center

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