DSS-E.01.02 — Atmospheric Corrosion Matte (SOx/NOx / “Acid Rain”)

Atmospheric corrosion matte is an appearance change on glass driven by acidic or pollutant-laden moisture (e.g., SOx/NOx, industrial emissions) and cyclic wet/dry exposure, producing surface hydration/leaching and very fine micro-texture. It presents as a non-directional, low-contrast milky haze that reduces specular clarity and can map runoff/edge dwell. Classification is appearance-only per VIS (method-agnostic). Inspect after Non-Invasive Reveal under VIS lighting/geometry; record surface numbering and worked-surface status.

• Global or zone-specific milkiness on outboard (#1) faces-greatest on windward or pollution-facing elevations.
• Rivulet ghosts or bloom near drip paths, sills, and frame edges where dwell times are higher.
• Under raking: fine, uniform scatter without clear lines, rings, or swirl geometry.

Surface-catch class (MSRT)

• SC-0 when only residue/films remain pre-etch (reveal patch clears to clarity).
• SC-1 when micro-texture exists (slight tactile interruption without chip flanks); SC-2 uncommon-if present, re-evaluate for Ch.03.03 mineral etching or M.02 abrasion fields.
• 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

• Non-directional milky matte; loss of “snap” in reflections; no chip-flank sparkle, no discrete pits.
• Rivulet/edge bias: subtle gradients tracing water behavior over time.

Viewing / lighting

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

Location / access

• Record pane ID and surface numbering (#1-#4; laminate-internal). Predominant on #1 outboard faces. Between-pane findings on #2/#3 via parallax → CAT-5 by location.

Mechanism cue (context)

• Urban/industrial corridors, near highways, power plants, cooling towers; lack of wash cycles or poor maintenance intervals; acid rain complaint history.

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

• CAT-1 (Benign / non-relief): Slight veil removable on reveal patch; SC-0; visible mainly at angle/raking. Indicative relief: 0-10 μm (optical film only).
• CAT-2 (Light): Persistent non-directional matte post-reveal with SC-1 in zones; limited standard-view impact. Indicative relief: ~10-40 μm (incipient micro-texture).
• CAT-3 (Moderate): Wide-area milkiness legible at standard distance; consistent SC-1; reflects long dwell/high exposure. Indicative relief: ~40-120 μm.
• Reclassify when: Distinct rings/runs with crystalline edges dominate → assess Ch.03.02 Mineral staining; etched fields with directional marks → consider M.02 abrasion overlay; pits/nodules → Th.01 hot particle family.
• 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. Detergent/surfactant film (R.04.01): Detergent shows iridescence and tool-path streaks; atmospheric matte is uniform/non-directional and persists after a simple wipe unless only residue was present.
• vs. Mineral system (Ch.03): Minerals exhibit rings/runs and may transition to etch halos; atmospheric matte is more global, edge-biased, and non-crystalline.
• vs. Fabric softener/additive film (R.04.02): Additive films show strong wetting contrast and fragrance; atmospheric matte shows uniform scatter with environmental context.
• vs. Coating anomalies (Co-family): Coating issues are often on #2/#3 or designated coated faces and show color/patchiness; atmospheric matte is substrate-side exposure-driven on #1.

• Photo set (VIS): 12 / 36 / 72 in, normal + oblique; raking macros of uniform scatter and edge/rivulet bias; façade context showing pollution sources/windward orientation. 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.

• E.01.02 Atmospheric Corrosion Matte (SOx/NOx / “Acid Rain”) - Non-directional milky matte with edge/rivulet bias on surface #___; post-reveal test patch shows [SC-0/SC-1]; visible at [12/36/72 in] under VIS geometry. Morphology: uniform scatter, loss of specular snap, no chip-flank sparkle, no pits. Classification: CAT-[1/2/3] by visibility and SC-class; reclassify to Ch.03 if mineral patterns dominate; CAT-5 if between-pane or coating-side loss on the surface to be worked. Forms + photo set attached; acceptance per VIS-A §6.