Plain / Bare Steel
Plain finish means no coating: the steel as heat treated, usually with a light oil film to stop rust in storage.
Plain finish at a glance
| Corrosion protection | Essentially none once the oil is gone |
|---|---|
| Friction | Depends on oil; dry plain steel K about 0.20 |
| Best for | Parts that will be painted, plated later or kept dry |
| Hydrogen risk | None from the finish |
These tables carry the same figures as the printed sheet below.
The printed sheet
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Text version of this sheet
Plain (bare) steel · no coating
FIELD IDENTIFICATION
What it is
Plain finish means no coating: the steel as heat treated, usually with a light oil film to stop rust in
storage.
PLAIN
Bare steel, usually lightly oiled
Plain finish at a glance
Corrosion protection
Essentially none once the oil is gone
Friction
Depends on oil; dry plain steel K about 0.20
Best for
Parts that will be painted, plated later or kept dry
Hydrogen risk
None from the finish
Key points
Plain Grade 8 or 10.9 bought for later plating must be plated by a process that controls hydrogen embrittlement.
Governing standards: No coating specification; purchase as "plain" or "plain + oil". 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-2D134C · thefastenerapp.com/fastener-guide/plating-coatings-finishes/plain-bare-steel · © The Fastener App. Reference only — verify the current governing standard, drawing and manufacturer data before specifying or installing.
