Coatings & Finishes - Master Selection Guide
Pick the finish from the environment, the fastener hardness and the assembly method. A finish never changes the grade, but it always changes friction and therefore torque.
Selection by environment
| Environment | Good choices | Avoid |
|---|---|---|
| Indoor, dry | Plain + oil, zinc plate, black oxide | - |
| Indoor, damp / light outdoor | Zinc plate Fe/Zn 8-12, zinc-nickel, zinc flake | Black oxide, plain |
| Outdoor, general | Hot-dip galvanized, mechanical zinc, zinc flake | Thin clear zinc |
| Coastal / marine | Stainless 316, heavy HDG, sealed zinc flake | Zinc plate, black oxide |
| High-hardness parts (HRC 39+) | Zinc flake, mechanical zinc | Electroplate without bake |
These tables carry the same figures as the printed sheet below.
The printed sheet
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Text version of this sheet
Coatings and finishes · master selection guide
What it is
FIELD IDENTIFICATION
Pick the finish from the environment, the fastener hardness and the assembly method. A finish never
changes the grade, but it always changes friction and therefore torque.
ZINC
YELLOW
HDG
FLAKE
BLACK
Finish is chosen for corrosion, friction and
appearance
Selection by environment
Environment
Good choices
Avoid
Indoor, dry
Plain + oil, zinc plate, black oxide
-
Indoor, damp / light outdoor
Zinc plate Fe/Zn 8-12, zinc-nickel, zinc flake
Black oxide, plain
Outdoor, general
Hot-dip galvanized, mechanical zinc, zinc flake
Thin clear zinc
Coastal / marine
Stainless 316, heavy HDG, sealed zinc flake
Zinc plate, black oxide
High-hardness parts (HRC 39+)
Zinc flake, mechanical zinc
Electroplate without bake
Key points
Electroplating can load high-hardness steel with hydrogen. Parts at roughly HRC 39 and above (Grade 8, 10.9, 12.9, A574) need a qualified process and a
prompt embrittlement-relief bake, or a non-electrolytic coating instead.
Always pair a coated bolt with a compatibly coated nut; HDG bolts need oversize-tapped HDG nuts.
Governing standards: ASTM B633; ASTM F1941/F1941M-16(2025); ASTM F2329/F2329M-15(2023); ASTM B695-21; ASTM F3393-24; ISO 4042:2022; ISO 10683:2018; ISO
10684:2004. Editions shown are the latest confirmed as of September 2026. The drawing and the governing standard always take precedence over this sheet.
torquing any fastener. Verify the current governing standard, project documents, OEM requirements, size, thread, coating and lot certification. To the fullest extent permitted by law, The Fastener App disclaims liability
arising from reliance on this reference.
Fastener Guide reference FG-BE771F · thefastenerapp.com/fastener-guide/plating-coatings-finishes/coatings-and-finishes-master-selection-guide · © The Fastener App. Reference only — verify the current governing standard, drawing and manufacturer data before specifying or installing.
