DSS-E.05.01 — UV-Induced Browning / Yellowing of Residues

UV-induced browning/yellowing of residues is an appearance change on glass caused by photo-oxidation and polymerization within organic surface films (detergent remnants, maintenance additives, kitchen/HVAC aerosols, tree resins/honeydew carryover), producing a persistent amber/yellow veil and wetting anomalies. With prolonged exposure, very shallow micro-texture may develop beneath the film. Classification is appearance-only per VIS (method-agnostic). Inspect after Non-Invasive Reveal under VIS lighting/geometry; record surface numbering and worked-surface status.

• Warm amber/yellow cast most apparent in reflections or when viewed across light-to-dark backgrounds; stronger on sun-exposed elevations.
• Patchy or uniform veils following wipe paths, spray cones, or airflow routes (interiors near kitchens/HVAC, exteriors near exhausts).
• Wetting contrast: areas bead/sheet differently due to altered surface energy.

Surface-catch class (MSRT)

• Typically SC-0 (film on top).
• Local SC-1 where long dwell + UV produced incipient substrate micro-texture or where grit was trapped in the film; SC-2 suggests misclassification-consider M.02 abrasion fields or Ch.03.03 mineral etching if matte persists after true film lift.
• Perform one light, non-marring pass on a small revealed test patch (substrate). Use polymer stylus if a functional coating is suspected. MSRT supports classification only.

Visual signature

• Amber/yellow veil with wipe geometry or air-path mapping; sometimes edges of patches appear slightly darker.
• No chip-flank sparkle, no discrete pits/fused nodules. After misting, wetting anomalies outline the film.

Viewing / lighting

• Evaluate clean & dry at 12 / 36 / 72 in, normal and oblique sweep (~60°-120°); use raking to reveal film thickness variations and edge outlines. Record distances/angles in-frame.

Location / access

• Record pane ID and surface numbering (#1-#4; laminate-internal). Occurs on outboard (#1) near exhaust/organics and inboard (#4) near kitchens/HVAC. Between-pane identification on #2/#3 via parallax → CAT-5 by location.

Mechanism cue (context)

• History of detergent/additive use, fragrance or surfactant residues, cooking aerosols, HVAC carryover, or nearby organics (sap/honeydew) with sun exposure.

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

• CAT-1 (Benign / non-relief): Thin amber veil; SC-0; angle/raking visible; clears fully on reveal patch. Indicative relief: 0-10 μm (optical film only).
• CAT-2 (Light): Persistent amber cast post-reveal with localized SC-1 (incipient substrate change); limited standard-view impact. Indicative relief: ~10-40 μm.
• CAT-3 (Moderate): Wide-area discoloration legible at standard distance, scattered SC-1; indicates long dwell/high UV dose or repeated deposition. Indicative relief: ~40-120 μm.
• Reclassify when: If oily/neutral film without yellowing dominates → R.04.03 HVAC oil or R.04.04 kitchen grease; if white/grey crystalline rims/etch dominate → Ch.03 mineral system; if linear swirls/webs persist → M.02 abrasion fields.
• 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” a response during classification.

• vs. Nicotine/tar film (R.04.05): Nicotine is brown/amber with odor and interior air-path mapping; UV browning may present exterior as well and aligns with sun exposure and prior organic residues.
• vs. Tree sap shadow (E.03.03): Sap shows discrete beads/stringers and post-lift shadow; UV-browned films are more uniform/patchy with wipe or airflow geometry.
• vs. Coating anomalies (Co-family): Coating issues are planar/patchy on designated coated faces and persist independent of cleaning history; browned films respond to film-lift testing and track usage/exposure.
• vs. Atmospheric matte (E.01.02): Atmospheric matte is non-directional, often edge/rivulet-biased; browned films show wipe/air-path mapping and color shift.

• Photo set (VIS): 12 / 36 / 72 in, normal + oblique; raking macros of film edges, color cast, and wetting anomalies; context frames showing sun-exposed elevation or source zones (kitchen/HVAC/exhaust). Record distance/angle in-frame.
• MSRT result (substrate): After a small reveal test patch and true film-lift, 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.

• E.05.01 UV-Induced Browning / Yellowing of Residues - Amber/yellow veil with wipe/air-path geometry on surface #___; post-reveal test patch shows [SC-0 film / SC-1 localized]; visible at [12/36/72 in] under VIS geometry. Morphology: photo-browned organic film, wetting anomalies, no chip-flank sparkle, no pits. Classification: CAT-[1/2/3] by visibility and SC-class; reclassify to R.04.03/R.04.04 (oily films), Ch.03 (mineral), or M.02 (abrasion) as indicated; CAT-5 if between-pane or coating-side loss on the surface to be worked. Forms + photo set attached; acceptance per VIS-A §6.