Cross-group finish comparison
Sherardized Zinc Coating vs Zinc Plating
Sherardized Zinc Coating (anodizing & conversion coatings) and Zinc Plating (electroplating & electroless plating) solve the same problem by different routes; sherardizing resists corrosion better (500–1,000 h vs 96–300 h salt spray).
Sherardized Zinc Coating
Anodizing & conversion coatings · $$$
Sherardizing is a thermal-diffusion zinc treatment for steel fasteners and small components, standardized by ASTM A1059.
Zinc Plating
Electroplating & electroless plating · $ · instant quote
Electrolytic zinc is a thin sacrificial coating for carbon steel hardware and parts.
When to choose which
Choose Sherardizing
Sherardizing is the pick when its strengths below matter more than Zinc plate's.
- Uniform 15–75 µm diffusion coating
- Good thread and recess coverage
- Sacrificial zinc corrosion protection
Choose Zinc plate
Choose Zinc plate when a thinner, widely available zinc finish is required.
- Low-cost sacrificial protection for steel
- SC1–SC4 provide 5, 8, 13, or 25 µm minimum zinc
- Rack or barrel processing supports both precision parts and fasteners
What the numbers say
- Sherardizing resists corrosion better (500–1,000 h vs 96–300 h salt spray).
- Sherardizing is the harder surface (250–400 HV vs 40–100 HV).
- Zinc plate is the lower-cost option ($).
- Zinc plate is the thinner coating (5–25 µm), so it disturbs tight fits less.
- Sherardizing tolerates more heat (250 °C continuous).
Scores side by side
Each score is 0–100 against every finish in this catalog. Corrosion is derived from salt-spray test duration and surface hardness from the finish layer's Vickers hardness where a measured figure exists; a finish that leaves the base metal's own surface is not rated for hardness. Cosmetic, lubricity and cost are FabDigit's engineering assessment. Scores and typical figures are screening data, not matched side-by-side tests or service-life rankings; ASTM B117 is a controlled salt-fog method, not a field-life prediction.
| Score | Sherardizing | Zinc plate |
|---|---|---|
| Corrosion resistance | 83 Very good | 60 Good |
| Surface hardness / wear | 56 Good | 30 Low |
| Cosmetic quality | 30 Low | 55 Good |
| Lubricity | 30 Low | 25 Low |
| Cost | 58 $$$ | 12 $ |
Key numbers
| Property | Sherardizing | Zinc plate |
|---|---|---|
| Thickness | 15–75 µm | 5–25 µm |
| Surface hardness | 250–400 HV | 40–100 HV |
| Salt-spray test duration | 500–1,000 h | 96–300 h |
| Max service temperature | 250 °C | 80 °C |
| Electrical | Conductive | Conductive |
| Colours | matte grey | clear blue, yellow iridescent, black, olive drab |
| Relative cost | Premium ($$$) | Budget ($) |
| Added lead time | 7–15 working days | 2–5 working days |
| RoHS | Compliant | Compliant |
| Instant quote | On request | Yes |
Bold marks the side that is ahead on a row where more (or less, for cost and lead time) is better. Ranges are the typical specification window; the drawing call-out fixes the class.
Which materials take each finish
| Material family | Sherardizing | Zinc plate |
|---|---|---|
| Steel | Yes | Yes |
| DMLS / SLM | With care | With care |
| Aluminum | No | Limited |
| Brass | No | Limited |
| Copper Alloy | No | Limited |
| Stainless Steel | No | Limited |
| Zinc Alloy | No | Limited |
Specifications and drawing call-outs
Sherardizing
No governing public specification — called out by name and thickness.
SHERARDIZE STEEL PARTS PER ASTM A1059, CLASS 30, 30 µm MINIMUM COATING THICKNESS; APPLY TRIVALENT PASSIVATION; THREADS SHALL ACCEPT GO GAUGE AFTER COATING
Zinc plate
- ASTM B633 — Standard Specification for Electrodeposited Coatings of Zinc on Iron and Steel
ZINC PLATE PER ASTM B633, SC3, TYPE V, CLEAR TRIVALENT PASSIVATE; 13 µm MIN; BAKE PER ASTM B850 WITHIN 1 H OF PLATING
Sherardizing vs Zinc plate — frequently asked
What is the difference between Sherardizing and Zinc plate?
Sherardized Zinc Coating (anodizing & conversion coatings) and Zinc Plating (electroplating & electroless plating) solve the same problem by different routes; sherardizing resists corrosion better (500–1,000 h vs 96–300 h salt spray). Sherardizing is the harder surface (250–400 HV vs 40–100 HV). Zinc plate is the lower-cost option ($).
When should I use Sherardizing instead of Zinc plate?
Conversely: choose Zinc plate when a thinner, widely available zinc finish is required.
Is Sherardizing or Zinc plate cheaper?
Zinc plate is the lower-cost finish ($ against $$$ for Sherardizing) among the finishes FabDigit quotes. Both are priced per part with a lot minimum; the exact figure appears on the instant quote once the part is uploaded.
Which lasts longer in salt spray, Sherardizing or Zinc plate?
Sherardizing. Sherardizing is rated 500–1,000 h and Zinc plate 96–300 h in neutral salt spray (ASTM B117 or the qualification hours of the governing specification). The figures are for the finish as specified on a clean, properly pre-treated substrate; sealing, thickness class and substrate alloy move them.