Guide
What “bare metal clean” means in practice
Every quote promises “cleaned to bare metal.” Fire marshals listen for it; insurers look for it on the written report. Operators often never see it defined. Secondary industry explainers of NFPA 96 (2024 edition) §12.6.5 treat it as an outcome: accessible exhaust surfaces cleaned until the underlying metal is visible — not a canopy wipe, not “degreased,” and not a polished hood face with a greasy plenum behind it. This page is a facilities check for verifying that outcome without inventing prices or guarantees.
Short answer
Bare metal means no grease film, no carbonized residue, and no tacky feel on the surfaces the crew could reach — metal color and texture visible, glove comes away clean. It applies to the full path (hood, plenum, ducts via panels, fan) where access exists. Areas that could not be reached belong on the service label and written report with a reason — that is an accessibility gap to fix, not proof the vendor “cleaned everything.” Verify with flashlight in the plenum, surface-by-surface report language, and before/after photos of plenum, duct opening, and fan wheel.
Outcome vs marketing language
| Phrase on the quote | What operators should check | Usually fails when… |
|---|---|---|
| “Cleaned to bare metal” | Metal visible; reflective under flashlight; seams/corners match flat panels | Uniform dull film left; corners dark while flats look clean |
| “Degreased” / “serviced” | Method words — ask for the bare-metal outcome and photos | Chemical applied, rinse incomplete, residue remains |
| “Hood cleaned” | Ask: canopy only, or plenum + duct + fan? | Visible canopy wipe; ducts and fan skipped |
| “Full system” | Panel openings tagged; fan hinged/opened; report lists each surface | No panel tags; 90-minute visit on a multi-hood path |
| “Looks new” | Not required — old steel can be bare metal with heat stain/patina | Confusing factory finish with grease removal |
Secondary Facilitec note: NFPA specifies the result, not the cleaning method. Grease is opaque; bare metal reflects. A glove test and a flashlight are the field checks AHJs use.
Surface-by-surface (accessible portions)
| Surface | Bare metal looks like | Common miss |
|---|---|---|
| Hood canopy interior | Seams, rivets, and flats all clear | Flats wiped; corners left |
| Plenum (behind filters) | Reflective metal; grease trough empty | Filters washed; plenum film left |
| Horizontal duct | Panel opened; interior scraped/washed; flashlight reflection | “Cleaned what we could reach” with no panels opened |
| Vertical riser | Access at levels; base cleanout emptied | Top or bottom only |
| Exhaust fan interior | Wheel blades show metal; housing and drain clear | Housing exterior wiped; blades coated |
| Filters | Operator daily/weekly job — separate from §12.6.5 fixed-path clean | Treating staff filter wash as the deep clean |
Credible bare-metal job
- Quote names hood + plenum + ducts + fan
- Written report lists surfaces cleaned and inaccessible areas with reasons
- Before/after photos: plenum, at least one duct opening, fan wheel
- Service label notes exclusions honestly
- Access-panel tags where panels were opened
Red flags
- “System cleaned” with no surface detail
- Label with zero exclusions on a known dead-end duct
- Photos of shiny canopy only — no duct/fan
- In-and-out visit far shorter than system size allows
- Confusing grease-depth gauge talk with “we left a film on purpose”
Field note — inaccessible ≠ “done”
- Secondary §12.6.5 applies to accessible portions. Secondary §12.6.4 expects the system to be made accessible (panels, fan hinge) where it is not.
- Honest label language: “vertical riser above second floor — no access; panel recommended” is useful. A blank exclusions line on that same system is not.
- FindHoodCleaner / Summit secondary notes: report should name areas cleaned and areas not cleaned with reasons; photos of bare metal are the operator’s fastest verify.
- Grease-depth gauges (inspection) and bare-metal outcome (cleaning) answer different questions — see the grease-depth thresholds guide.
Operator verification checklist
- Pull one filter after the job — flashlight into the plenum; look for reflection and a clean trough.
- Read the written report — surface-by-surface findings, not one sentence “hood system cleaned.”
- Demand path photos — plenum, duct through a panel, fan wheel; timestamped if the vendor offers it.
- Check the service label for exclusions — match against known missing panels or lift-off-only fans.
- Confirm panel tags — opened panels should show who/when (secondary §12.6.10 pattern).
- Compare time to system size — secondary industry timing notes: a full single-hood moderate kitchen is commonly multi-hour work, not a rushed canopy pass.
- Keep the file together — label + tags + report + photos for AHJ and insurer (see cleaning report checklist).
Who it’s for / not for
- For: kitchen managers comparing quotes that all say “bare metal”; multi-unit operators standardizing report language; anyone who got a canopy wipe that failed inspection
- Not for: claiming a specific NFPA section number for your city without checking the adopted edition; inventing photo-count requirements; chemical/runoff rules (use the runoff guide); legal advice
Sources
- Facilitec Southwest — “Cleaned to Bare Metal” / NFPA 96 §12.6.5 (secondary explainer; outcome standard, surface table, verification)
- FindHoodCleaner — professional hood cleaning before & after (secondary; bare-metal visual checks, photo/sticker expectations)
- Summit Facility Solutions — NFPA 96 hood cleaning guide (secondary; path coverage + areas-not-cleaned documentation)
- FindHoodCleaner — hood cleaning myths (secondary; canopy-only vs full path)
- US Made Supply — NFPA 96 overview (secondary; inaccessible areas / documentation notes)
- HoodFilters — NFPA 96 reference excerpts (secondary manufacturer summary; verify against your adopted edition)
- Total Food — exhaust hood cleaning FAQ (secondary; industry “bare metal” language + Grease Gauge mention)
Next step
On the next clean, require three photos (plenum, one duct opening, fan wheel) and a report line for any inaccessible section. Walk the plenum with a flashlight before you sign off. If panels or a fan hinge are missing, treat that as a work order — not a forever excuse. Confirm wording against your AHJ’s adopted edition; this page is secondary, not legal advice.