FabDigitFabDigit

Electrophoretic Coating

Paint, powder & polymer coatings · Electrolytic bath

E-coating deposits a waterborne organic film on an electrically conductive part by electrophoresis.

CNC machiningSheet metalStandard cost $$Insulating
Quote a part with E-coatCompare paint, powder & polymer coatings
Electrophoretic Coating on a machined part

What is E-coat?

It is used as a uniform corrosion-resistant primer with excellent throwing power into recesses and complex assemblies.

How it works

The cleaned and pretreated workpiece is immersed in a waterborne coating bath and connected as an electrode, most commonly as the cathode. Direct current drives charged resin particles toward the surface, where they deposit and become electrically resistive, helping the film self-limit. Bath circulation and voltage provide coverage in cavities that spray methods struggle to reach. The part is rinsed to recover drag-out and then baked to crosslink the deposited resin.

Why specify it

  • Typical film thickness is 15–35 µm
  • Excellent throwing power reaches recesses and complex frames
  • Self-limiting deposition produces comparatively uniform film
  • Works well as a corrosion-resistant primer under powder or liquid topcoat

Where it falls short

  • Only electrically conductive, fully immersible parts can be coated
  • Closed cavities need drain and vent paths
  • Bare sharp edges can remain weaker than broad faces
  • Baking can damage heat-sensitive inserts and assemblies

E-coat at a glance

E-coat is strongest on corrosion protection (83 of 100), at a standard cost.

Corrosion protectionVery good83 / 100
Surface hardnessLow15 / 100
Cosmetic qualityGood55 / 100
LubricityLow15 / 100
Relative costStandard35 / 100
CorrosionHardnessCosmeticLubricityEconomy

Each score is 0–100 against every finish in this catalog. Corrosion comes from salt-spray life (ASTM B117, log scale) and hardness from the finish layer's Vickers or pencil hardness; cosmetic, lubricity and cost are FabDigit's engineering assessment. Economy on the radar is the inverse of cost.

E-coat key numbers

Typical values from the governing specifications and shop practice; bars are this finish against the highest value among paint, powder & polymer coatings finishes.

Thickness15–35 µm0.59–1.4 mil
Salt spray500–1,000 h
Max service temp.150 °C302 °F
Thickness
15–35 µm for cathodic epoxy e-coat
Hardness
2H–4H pencil hardness (ASTM D3363) — cathodic epoxy e-coat
Corrosion (salt spray)
500–1,000 h per ASTM B117 on pretreated steel, typical automotive cathodic-epoxy systems — Hours depend on pretreatment, edge geometry, and the named specification; this is a common qualified-system band, not a universal ASTM minimum.
Electrical
Insulating
Colours
  • black
  • gray
  • white
Appearance
Uniform, smooth, and usually low- to medium-gloss; often used as a primer rather than a final cosmetic surface.

Where E-coat sits among all finishes

Surface hardness (Vickers, log scale) against corrosion protection (salt-spray hours, log scale) for every coating FabDigit offers, one cloud per finish group. E-coat is highlighted; hover a dot for its name or open the full map.

02550751000255075100Corrosion protection (0–100)Surface hardness (HV, log scale, 0–100)Plating — 19 finishesHard coatings — 17 finishesAnodize & conversion — 8 finishesPaint & powder — 7 finisheshard, low corrosion protectionhard and protectiveprotective, softsoft, little protectionType II anodize — corrosion 71, hardness 54BSA anodize — corrosion 71, hardness 52Type I anodize — corrosion 71, hardness 49Hard anodize — corrosion 71, hardness 61PTFE hard anodize — corrosion 71, hardness 61Nitriding — corrosion 55, hardness 73PEO — corrosion 70, hardness 74Sherardizing — corrosion 83, hardness 56Brass plate — corrosion 35, hardness 44Bronze plate — corrosion 40, hardness 49Cadmium plate — corrosion 70, hardness 26Copper plate — corrosion 32, hardness 39Decorative chrome — corrosion 64, hardness 71Electroless copper — corrosion 20, hardness 41Electroless nickel — corrosion 70, hardness 68Nickel plate — corrosion 51, hardness 55Gold plate — corrosion 68, hardness 39Hard chrome — corrosion 40, hardness 73Hot-dip zinc — corrosion 90, hardness 42Nickel-PTFE — corrosion 72, hardness 57Silver plate — corrosion 55, hardness 39Solder plate — corrosion 42, hardness 9Tin plate — corrosion 34, hardness 0Zinc plate — corrosion 60, hardness 30Zinc-nickel — corrosion 86, hardness 60Cerakote — corrosion 83, hardness 27Epoxy coat — corrosion 83, hardness 15Powder coat — corrosion 83, hardness 14Wet paint — corrosion 59, hardness 10AlCrN PVD — corrosion 58, hardness 93AlTiN PVD — corrosion 52, hardness 94CrN PVD — corrosion 62, hardness 83DLC — corrosion 55, hardness 93MoS2 PVD — corrosion 20, hardness 26TiAlN PVD — corrosion 50, hardness 93TiCN PVD — corrosion 40, hardness 92TiB2 PVD — corrosion 40, hardness 94TiN PVD — corrosion 45, hardness 87WC/C PVD — corrosion 48, hardness 77ZrN PVD — corrosion 52, hardness 90CVD alumina — corrosion 70, hardness 85CVD TiCN — corrosion 38, hardness 92CVD TiN — corrosion 45, hardness 87Multilayer CVD — corrosion 62, hardness 88HVOF coating — corrosion 78, hardness 77Plasma spray — corrosion 60, hardness 68Plastic chrome — corrosion 72, hardness 71Electroless plastic — corrosion 58, hardness 39Clear coat — corrosion 20, hardness 12Soft-touch — corrosion 20, hardness 5PLATINGHARD COATINGSANODIZE & CONVERSIONPAINT & POWDERPowder coatEpoxy coatType II anodizeZinc plateZinc-nickelHard chromeDLCTiN PVDTin plateCadmium plateCerakoteWet paintHot-dip zincNitridingHVOF coatingE-coat — corrosion 83, hardness 15E-coat
02550751000255075100Corrosion protection (0–100)Surface hardness (HV, log scale, 0–100)Plating — 19 finishesHard coatings — 17 finishesAnodize & conversion — 8 finishesPaint & powder — 7 finishesType II anodize — corrosion 71, hardness 54BSA anodize — corrosion 71, hardness 52Type I anodize — corrosion 71, hardness 49Hard anodize — corrosion 71, hardness 61PTFE hard anodize — corrosion 71, hardness 61Nitriding — corrosion 55, hardness 73PEO — corrosion 70, hardness 74Sherardizing — corrosion 83, hardness 56Brass plate — corrosion 35, hardness 44Bronze plate — corrosion 40, hardness 49Cadmium plate — corrosion 70, hardness 26Copper plate — corrosion 32, hardness 39Decorative chrome — corrosion 64, hardness 71Electroless copper — corrosion 20, hardness 41Electroless nickel — corrosion 70, hardness 68Nickel plate — corrosion 51, hardness 55Gold plate — corrosion 68, hardness 39Hard chrome — corrosion 40, hardness 73Hot-dip zinc — corrosion 90, hardness 42Nickel-PTFE — corrosion 72, hardness 57Silver plate — corrosion 55, hardness 39Solder plate — corrosion 42, hardness 9Tin plate — corrosion 34, hardness 0Zinc plate — corrosion 60, hardness 30Zinc-nickel — corrosion 86, hardness 60Cerakote — corrosion 83, hardness 27Epoxy coat — corrosion 83, hardness 15Powder coat — corrosion 83, hardness 14Wet paint — corrosion 59, hardness 10AlCrN PVD — corrosion 58, hardness 93AlTiN PVD — corrosion 52, hardness 94CrN PVD — corrosion 62, hardness 83DLC — corrosion 55, hardness 93MoS2 PVD — corrosion 20, hardness 26TiAlN PVD — corrosion 50, hardness 93TiCN PVD — corrosion 40, hardness 92TiB2 PVD — corrosion 40, hardness 94TiN PVD — corrosion 45, hardness 87WC/C PVD — corrosion 48, hardness 77ZrN PVD — corrosion 52, hardness 90CVD alumina — corrosion 70, hardness 85CVD TiCN — corrosion 38, hardness 92CVD TiN — corrosion 45, hardness 87Multilayer CVD — corrosion 62, hardness 88HVOF coating — corrosion 78, hardness 77Plasma spray — corrosion 60, hardness 68Plastic chrome — corrosion 72, hardness 71Electroless plastic — corrosion 58, hardness 39Clear coat — corrosion 20, hardness 12Soft-touch — corrosion 20, hardness 5PLATINGHARD COATINGSANODIZE & CONVERSIONPAINT & POWDERPowder coatZinc plateE-coat — corrosion 83, hardness 15E-coat
Anodize & conversionPlatingPaint & powderHard coatings

Specifications for E-coat

The documents a drawing cites to define this finish, with the Type / Class rows that apply. Each links to a page explaining the standard.

Drawing call-out

CATHODIC E-COAT, BLACK, 20–30 µm DFT; MASK THREADS, ELECTRICAL CONTACTS, AND DATUM TARGETS; PROVIDE COMPLETE DRAINAGE

Which materials take E-coat?

Verdict per material family, with the grades that behave differently. Each family links to its datasheets in the material library.

Material familyVerdictNotes
Aluminum
YesRequires compatible pretreatment and bath controls.
Steel
YesPrimary high-volume substrate after suitable pretreatment.
Brass
With carePossible; zinc and copper bleed can stain the film.
Copper Alloy
With carePossible; pretreatment and bake staining must be validated.
DMLS / SLM
With careMetal AM parts can be e-coated after powder removal; internal passages need drain paths.
Magnesium Alloy
With careUse a validated magnesium pretreatment and corrosion system.
Stainless Steel
With careConductive and immersible, but adhesion needs abrasion and a compatible pretreatment.
Titanium
With careConductive, but pretreatment and adhesion need qualification.
Zinc Alloy
With carePretreatment, outgassing, and bake response require validation.
FDM
NoNonconductive polymers cannot be e-coated without a conductive layer.
MJF
NoNonconductive polymers cannot be e-coated without a conductive layer.
Polymer
NoConventional electrophoretic deposition requires an electrically conductive substrate.
SLA
NoNonconductive polymers cannot be e-coated without a conductive layer.
SLS
NoNonconductive polymers cannot be e-coated without a conductive layer.

How E-coat is applied, and what it does to the part

  1. 1Clean
  2. 2Pretreat
  3. 3Rinse
  4. 4Electrocoat by immersion
  5. 5Ultrafiltrate rinse
  6. 6Drain
  7. 7Bake cure
  8. 8Inspect
DimensionsAllow 15–35 µm on all immersed conductive faces, including recesses and internal passages reached by the bath.
Build-up per side15–35 µm — Deposited film adds approximately its dry-film thickness to every wetted conductive surface.
MaskingUsually needed. Mask electrical contacts, grounding points, close fits, threads, sealing lands, and surfaces that must not receive immersion coating.
ElectricalInsulating
Temperature limit150 °C (302 °F) continuous
AppearanceUniform, smooth, and usually low- to medium-gloss; often used as a primer rather than a final cosmetic surface.
Added lead time4–8 working days on top of the bare part

Design rules for E-coat

What to decide on the drawing before the part goes to the finisher.

  1. Provide vents at cavity high points and drains at low points.Air pockets and trapped bath prevent complete coating.
  2. Avoid sealed overlapping joints.Entrapped chemistry can bleed during cure.
  3. Define rack contact locations.The part must conduct current and the contact leaves a witness.
  4. Mask functional threads and contacts.The 15–35 µm insulating film reaches recesses unusually well.

E-coat versus the alternatives

Finishes engineers weigh against E-coat, and when each wins.

FinishCorrosionHardnessCosmeticCostThicknessChoose it when
E-coat
this page
831555$$15–35 µm—
Powder Coating
E-coat vs Powder Coating →
831485$$50–150 µmwhen thicker decorative topcoat performance is needed
Epoxy Coating
E-coat vs Epoxy Coating →
831555$$$50–200 µmwhen immersion processing is impractical
CorrosionHardnessCosmeticLubricityEconomy
E-coatPowder Coating

The radar overlays E-coat with Powder Coating, its most common alternative — chosen when thicker decorative topcoat performance is needed. Scores in the table are 0–100 across every finish in the catalog.

Cost, lead time and compliance

Relative cost

Electrophoretic Coating is a standard-cost finish ($$): cheaper than about 60 % of the finishes FabDigit quotes.

Finishing is priced per part with a lot minimum, from FabDigit's own China-side rates cross-checked against US job-shop pricing. The exact figure appears on the instant quote once the part is uploaded.

Lead time and compliance

Added lead time4–8 working days
RoHSCompliant
NotesWaterborne bath and rinse recovery reduce coating loss; confirm the exact pretreatment and pigment system.

What E-coat is used for

  • Automotive frames
  • Complex welded brackets
  • Appliance bases
  • Underbody components
  • Primer for powder-coated assemblies

E-coat — frequently asked

e-coat vs powder coat

E-coat is typically 15–35 µm and reaches recesses by immersion and electric field. Powder coat is commonly 50–150 µm, provides broader decorative options, but suffers more Faraday-cage difficulty in deep pockets.

how thick is e-coat

Cathodic epoxy e-coat is commonly specified at 15–35 µm. The exact range must match the supplier's bath and corrosion-performance requirement.

does e-coat cover inside cavities

Yes, it has excellent throwing power compared with spray coatings. Cavities still need electrical continuity, bath access, venting, and drainage.

can e-coat be used as a final finish

It can be the final black functional finish, but it is often used as a corrosion-resistant primer. A powder or liquid topcoat adds color, weathering, and cosmetic durability.

does e-coat affect threads

Yes. Its throwing power means even recessed threads may receive 15–35 µm of insulating film. Mask functional threads unless fit allowance and electrical behavior are intentional.