Anodizing, conversion & passivation · finish comparison
Citric Acid Passivation vs Stainless Steel Passivation
Citric Acid Passivation and Stainless Steel Passivation are both passivation & electropolishing finishes; stainless passivation is the lower-cost option ($).
Citric Acid Passivation
Passivation & electropolishing · $
Citric-acid passivation is a separately searched and specified stainless-steel passivation route that removes free iron without nitric acid.
Stainless Steel Passivation
Passivation & electropolishing · $ · instant quote
Passivation removes free iron and shop contamination from stainless steel so its chromium-rich passive film can reform.
When to choose which
Choose Citric passivation
Choose Citric passivation when nitric acid handling is not permitted.
- Adds 0 µm measurable buildup
- Avoids nitric-acid fumes and nitrate waste
- ASTM A967 provides multiple citric treatment windows
Choose Stainless passivation
Choose Stainless passivation when either nitric or citric processing may be selected.
- Removes embedded free iron that can rust
- Adds no measurable coating thickness
- ASTM A967 and AMS 2700 offer nitric and citric methods
What the numbers say
- Stainless passivation 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 | Citric passivation | Stainless passivation |
|---|---|---|
| Corrosion resistance | 34 Low | 34 Low |
| Surface hardness / wear | — — | — — |
| Cosmetic quality | 18 Low | 18 Low |
| Lubricity | 10 Minimal | 10 Minimal |
| Cost | 12 $ | 10 $ |
Key numbers
| Property | Citric passivation | Stainless passivation |
|---|---|---|
| Thickness | 0 µm | 0 µm |
| Electrical | Unchanged | Unchanged |
| Relative cost | Budget ($) | Budget ($) |
| Added lead time | 2–4 working days | 2–4 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 | Citric passivation | Stainless passivation |
|---|---|---|
| Stainless Steel | Yes | Yes |
| DMLS / SLM | With care | With care |
| Cobalt-Chrome Alloy | — | Limited |
| Titanium | Limited | Limited |
Specifications and drawing call-outs
Citric passivation vs Stainless passivation — frequently asked
What is the difference between Citric passivation and Stainless passivation?
Citric Acid Passivation and Stainless Steel Passivation are both passivation & electropolishing finishes; stainless passivation is the lower-cost option ($).
When should I use Citric passivation instead of Stainless passivation?
Choose Citric passivation when nitric acid handling is not permitted. Conversely: choose Stainless passivation when either nitric or citric processing may be selected.
Is Citric passivation or Stainless passivation cheaper?
Stainless passivation is the lower-cost finish ($ against $ for Citric passivation) 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.