DSS-R.04.03 — HVAC Aerosol / Oil Film

HVAC aerosol / oil film is an appearance change on glass from airborne oils, plasticizers, and fine condensables emitted or entrained by HVAC systems, kitchens, shop floors, or mechanical rooms, depositing as a uniform, slightly tacky veil that captures dust. It often shows gradients aligned to supply/return paths or equipment proximity. Classification is appearance-only per VIS (method-agnostic). Inspect after Non-Invasive Reveal under VIS lighting/geometry; record surface numbering and worked-surface status.

• Broad, low-contrast smear/veil across interior faces near diffusers/returns, elevator lobbies, or shop areas (machining, forklifts).
• Dust-capture patterning (fine particulate embedded), finger wipe “windows” from ad-hoc cleaning, and edge build near frames.
• In raking: soft glow with wipe overlap arcs where partial cleanups occurred.

Surface-catch class (MSRT)

• Typically SC-0 (thin oil film).
• SC-1 may appear where abrasive cloths or dust-laden wipers produced very shallow micro-texture during attempts to clean; SC-2 uncommon-recheck classification if observed.
• Perform one light, non-marring pass on a small revealed test patch (substrate). Use a polymer stylus if a functional coating is suspected. MSRT supports classification only.

Visual signature

• Uniform smeary glow with dust capture; hand/finger “windows”; directional gradient pointing back to grille or process source.
• No chip-flank sparkle (not mechanical scoring); no discrete fused pits (not hot particle).

Viewing / lighting

• Evaluate clean & dry at 12 / 36 / 72 in, normal incidence and oblique sweep (~60°-120°); raking macros to resolve sheen, dust embed, and overlap edges. Record distances/angles in-frame.

Location / access

• Record pane ID and surface numbering (#1-#4; laminate-internal). Interior inboard (#4) faces are common. If fixed parallax places the veil between panes (#2/#3), classify CAT-5 by location (out of in-place scope) and refer.

Mechanism cue (context)

• Nearby supply/return diffusers, kitchen make-up air, mechanical rooms, industrial oils, vape/smoke areas, parking exhaust; presence of oily dust on frames/sills.

Assign CAT by visibility at acceptance geometry and MSRT after a controlled reveal test. Depth values are indicative-field measurement not required.

• CAT-1 (Benign / non-relief): Thin oil veil; SC-0; seen mainly at angle/raking; minor dust capture. Indicative relief: 0-10 μm (optical).
• CAT-2 (Light): Persistent film with dust embed and localized SC-1 from prior wiping; limited impact at standard view. Indicative relief: ~10-40 μm.
• CAT-3 (Moderate): Wide-area contamination legible at standard distance (global haze, patterning near grilles); scattered SC-1 in wipe attempts. Indicative relief: ~40-120 μm (film stack).
• Reclassify when: After true residue lift, any modeled micro-texture or SC>0 persists → evaluate under M.02 (abrasion fields); if soot/combustion dominates, consider E.01.03 Soot/particulate pollution film.
• CAT-5 (by condition/location): Between-pane/inaccessible by parallax, integrity indicators, or confirmed functional-coating loss on the surface to be worked → CAT-5.

CAT is appearance-based; acceptance is separate under VIS-A at 12/36/72 in. Do not abrade to “force” removal during classification.

• vs. Kitchen grease/aerosol film (R.04.04): Kitchen grease presents heavier tack, yellow/brown tone, and localized spatter near cooking lines; HVAC films are broader, gradiated with HVAC alignment.
• vs. Detergent/surfactant film (R.04.01): Detergent films show tool-path streaks and iridescence; HVAC films are uniform veils with dust embed and source-aligned gradient.
• vs. Fabric softener/additive film (R.04.02): Additive films show strong wetting contrast upon mist; HVAC films show less distinct wetting boundaries and more dust capture.
• vs. Soot/particulate pollution film (E.01.03): Soot films are darker/grey, particulate-dominant; HVAC oils are clear/amber, smear easily, and leave oily residue on a clean cloth.

• Photo set (VIS): 12 / 36 / 72 in, normal + oblique; raking macros of sheen/dust embed and wipe overlaps; context frames of HVAC grilles/returns showing alignment. Record distance/angle in-frame.
• MSRT result (substrate): After a small reveal test patch, perform one light, non-marring pass; record SC-class (SC-0/SC-1/SC-2).
• Forms: Pane ID; product family & surface numbering; worked surface Y/N; functional coating present on worked surface? (Y/N/Unknown); reveal status; lighting/time; geometry checklist; photos attached.
• Acceptance split: Post-restoration acceptance per VIS-A §6; classification ≠ acceptance. Coated-face appearance rules apply per VIS §6.2.e when the worked surface is a factory functional coating.

• R.04.03 HVAC Aerosol / Oil Film - Uniform smeary veil with dust capture and source-aligned gradient on surface #___; post-reveal test patch shows [SC-0/SC-1]; visible at [12/36/72 in] under VIS geometry. Morphology: oily smear, finger wipe windows, no chip-flank sparkle, no pits. Classification: CAT-[1/2/3] by visibility and SC-class; CAT-5 if between-pane or coating-side loss on the surface to be worked. Forms + photo set attached; acceptance per VIS-A §6.