Cross-group finish comparison
Electropolishing vs Mirror Polishing
Electropolishing (passivation & electropolishing) and Mirror Polishing (mechanical finishing) solve the same problem by different routes; electropolishing resists corrosion better.
Electropolishing
Passivation & electropolishing · $$$ · instant quote
Electropolishing is controlled anodic dissolution that brightens, deburrs, and smooths stainless steel and other qualified alloys.
Mirror Polishing
Mechanical finishing · $$$$ · instant quote
Mirror polishing removes visible directional scratches and buffs the surface to high specular reflectance.
When to choose which
Choose Electropolishing
Electropolishing is the pick when its strengths below matter more than Mirror polish's.
- Removes about 5–25 µm per surface
- Reduces microscopic peaks and cleanability traps
- Deburrs very small edges without embedded abrasive
Choose Mirror polish
Choose Mirror polish when a mechanical mirror is acceptable and stock removal must be minimal.
- Typical Ra 0.025–0.10 µm (1–4 µin)
- Produces premium specular appearance
- Improves release on polished mold faces
What the numbers say
- Electropolishing resists corrosion better.
- Electropolishing is the lower-cost option ($$$).
- Electropolishing is the thinner coating (removes 5–25 µm), so it disturbs tight fits less.
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 | Electropolishing | Mirror polish |
|---|---|---|
| Corrosion resistance | 45 Fair | 10 Minimal |
| Surface hardness / wear | — — | — — |
| Cosmetic quality | 82 Very good | 95 Excellent |
| Lubricity | 35 Fair | 25 Low |
| Cost | 54 $$$ | 78 $$$$ |
Key numbers
| Property | Electropolishing | Mirror polish |
|---|---|---|
| Thickness | removes 5–25 µm | 0 µm |
| Electrical | Unchanged | Unchanged |
| Relative cost | Premium ($$$) | High ($$$$) |
| Added lead time | 3–6 working days | 3–10 working days |
| RoHS | Compliant | Compliant |
| Instant quote | Yes | Yes |
Bold marks the side that is ahead on a row where more (or less, for cost and lead time) is better. Ranges are the typical specification window; the drawing call-out fixes the class.
Which materials take each finish
| Material family | Electropolishing | Mirror polish |
|---|---|---|
| Brass | Limited | Yes |
| Copper Alloy | Limited | Yes |
| Stainless Steel | Yes | Yes |
| Steel | Limited | Yes |
| Aluminum | Limited | With care |
| Cobalt-Chrome Alloy | With care | — |
| DMLS / SLM | With care | — |
| Magnesium Alloy | No | With care |
| Nickel Alloy | With care | — |
| Titanium | Limited | With care |
| Zinc Alloy | No | With care |
| Polymer | No | Limited |
Specifications and drawing call-outs
Electropolishing
- ASTM B912 — Standard Specification for Passivation of Stainless Steels Using Electropolishing
ELECTROPOLISH STAINLESS STEEL PER ASTM B912; REMOVE 0.0002–0.0005 IN PER SURFACE; FINAL Ra 0.4 µm MAX; MASK THREADS
Mirror polish
No governing public specification — called out by name and thickness.
MIRROR POLISH DESIGNATED SURFACES TO Ra 0.05 µm MAX, ASTM A480/A480M No. 8 APPEARANCE, NO VISIBLE PITS OR DIRECTIONAL LINES
Electropolishing vs Mirror polish — frequently asked
What is the difference between Electropolishing and Mirror polish?
Electropolishing (passivation & electropolishing) and Mirror Polishing (mechanical finishing) solve the same problem by different routes; electropolishing resists corrosion better. Electropolishing is the lower-cost option ($$$). Electropolishing is the thinner coating (removes 5–25 µm), so it disturbs tight fits less.
When should I use Electropolishing instead of Mirror polish?
Conversely: choose Mirror polish when a mechanical mirror is acceptable and stock removal must be minimal.
Is Electropolishing or Mirror polish cheaper?
Electropolishing is the lower-cost finish ($$$ against $$$$ for Mirror polish) 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.