Mechanical finishing & post-processing · finish comparison
Lapping vs Mirror Polishing
Lapping and Mirror Polishing are both mechanical finishing finishes; mirror polish resists corrosion better.
Lapping
Mechanical finishing · $$$$
Lapping is a precision loose-abrasive process used to improve flatness, parallelism, and very fine roughness.
Mirror Polishing
Mechanical finishing · $$$$ · instant quote
Mirror polishing removes visible directional scratches and buffs the surface to high specular reflectance.
When to choose which
Choose Lapped
Choose Lapped when flatness and sub-0.1 µm Ra are functional requirements.
- Achieves Ra 0.01–0.10 µm (0.4–4 µin)
- Improves flatness and parallelism
- Produces high bearing area
Choose Mirror polish
Mirror polish is the pick when its strengths below matter more than Lapped's.
- Typical Ra 0.025–0.10 µm (1–4 µin)
- Produces premium specular appearance
- Improves release on polished mold faces
What the numbers say
- Mirror polish resists corrosion better.
- Lapped is the lower-cost option ($$$$).
Scores side by side
Each score is 0–100 against every finish in this catalog. Corrosion is derived from salt-spray test duration and surface hardness from the finish layer's Vickers hardness where a measured figure exists; a finish that leaves the base metal's own surface is not rated for hardness. Cosmetic, lubricity and cost are FabDigit's engineering assessment. Scores and typical figures are screening data, not matched side-by-side tests or service-life rankings; ASTM B117 is a controlled salt-fog method, not a field-life prediction.
| Score | Lapped | Mirror polish |
|---|---|---|
| Corrosion resistance | 0 Minimal | 10 Minimal |
| Surface hardness / wear | — — | — — |
| Cosmetic quality | 70 Very good | 95 Excellent |
| Lubricity | 30 Low | 25 Low |
| Cost | 70 $$$$ | 78 $$$$ |
Key numbers
| Property | Lapped | Mirror polish |
|---|---|---|
| Thickness | 0 µm | 0 µm |
| Electrical | Unchanged | Unchanged |
| Relative cost | High ($$$$) | High ($$$$) |
| Added lead time | 3–10 working days | 3–10 working days |
| RoHS | Compliant | Compliant |
| Instant quote | On request | Yes |
Bold marks the side that is ahead on a row where more (or less, for cost and lead time) is better. Ranges are the typical specification window; the drawing call-out fixes the class.
Which materials take each finish
| Material family | Lapped | Mirror polish |
|---|---|---|
| Brass | With care | Yes |
| Ceramic | Yes | — |
| Copper Alloy | With care | Yes |
| Stainless Steel | Yes | Yes |
| Steel | Yes | Yes |
| Aluminum | With care | With care |
| Magnesium Alloy | With care | With care |
| Titanium | With care | With care |
| Zinc Alloy | With care | With care |
| Polymer | No | Limited |
Lapped vs Mirror polish — frequently asked
What is the difference between Lapped and Mirror polish?
Lapping and Mirror Polishing are both mechanical finishing finishes; mirror polish resists corrosion better. Lapped is the lower-cost option ($$$$).
When should I use Lapped instead of Mirror polish?
Choose Lapped when flatness and sub-0.1 µm Ra are functional requirements.
Is Lapped or Mirror polish cheaper?
Lapped is the lower-cost finish ($$$$ against $$$$ 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.