Finishes
Finishes such as coating or plating is often applied to fasteners for various reasons. The most common reason is for rust protection. Other reasons include: appearance, reducing friction, prevent galling, ext.
| Finish | Corrosion Resistance | Method of Finish | Appearance |
|---|---|---|---|
| Plain | NONE | N/A | Dark gray or dull black. May have light oil residue. |
| Black Phosphate | POOR | Conversion Coating | Dull grayish black |
| Black Oxide | FAIR | Conversion Coating | Black, sometimes with oil topcoat |
| Nickel | GOOD | Electrically | Bright shiny silver |
| Chrome | GOOD | Electrically | Bright, lustrous silver |
| Zinc | GOOD | Electrically | Shiny silver. Can be iridescent. |
| Zinc w/ Dichromate | VERY GOOD | Electrically | Often shiny yellow, sometimes other colors. |
| Mechanical Galvanized | VERY GOOD | Cold-Welded | Dull gray |
| Cadmium (Cad) | VERY GOOD | Electrically | Bright silver/gray |
| Hot-Dip Galvanized | EXCELLENT | Zinc Immersion | Dull gray - Can have rough textured appearance |
| PTFE | EXCELLENT | Dip Spin | Most commonly blue in color, however there are several colors available |