E-coat (electrocoat)

E-coat, or cathodic electrocoating, immerses a pretreated part in a water-based paint bath and applies DC current so paint deposits evenly on every wetted surface, including recesses, edges and tube interiors. Films are typically 0.6–1.2 mil (15–30 µm), cured near 350–375 °F (175–190 °C). Epoxy e-coat gives excellent corrosion protection but chalks in sunlight; acrylic e-coat is UV stable.

Add it to a part

Applies to: Steel, zinc-plated steel, aluminum, zinc and aluminum die castings, springs and wire forms
Adds: 4 days
Cost: Low

Colors

Black
Gray
Clear or colored acrylic on request

Specs

E-coat (electrocoat) specifications
Film thickness	0.6–1.2 mil (15–30 µm) typical
Coverage	Uniform on edges, recesses and tube interiors
Cure	About 350–375 °F (175–190 °C) for 20–30 min
Corrosion resistance	Commonly 500–1,000 h ASTM B117 over zinc phosphate, epoxy systems
UV resistance	Epoxy: poor, topcoat for sun; acrylic: good
Colors	Mostly black and gray; acrylic offers more colors

Call out on the drawing

ASTM B117 (salt spray)
SAE J2334 (cyclic corrosion)
ASTM D3359 (adhesion)
Automotive OEM paint and corrosion specs as called on the drawing

Materials it suits

Common on

Questions

E-coat vs powder coat?

E-coat is thinner and more uniform and reaches recesses and edges that powder cannot, which makes it the corrosion base for automotive and complex stampings. Powder is thicker and tougher with more colors. Many parts get e-coat as a primer with powder or paint on top.

Is e-coat UV resistant?

Epoxy e-coat is not; it chalks and fades in sunlight, so it is used on underbody and interior parts or as a primer. Acrylic e-coat holds up to UV for exterior parts that need a single coat.

Can springs be e-coated?

Yes. E-coat is common on springs and wire forms because it covers coils evenly without bridging. The cure temperature is below typical music wire stress relief temperatures, so spring properties are not affected.