DSS-A.01.05 — Low-E / Functional-Coating Appearance Change Inside Cavity (#2 / #3)

Non-uniform appearance change (e.g., patchiness, color shift/iridescence, fine “islands”/pinholes, micro-mottle) on a functional coating located on IGU cavity faces (#2 or #3). Because the affected face is between panes, it is not an exposed worked surface and is not addressable in-place; classification is governed by location/condition. VIS defines surface numbering and treats between-pane (fixed parallax) cues as out-of-scope by location. “Coating anomaly” is a defined VIS term (adapted from ASTM C1376).

• Patchy or blotchy zones, subtle color non-uniformity/iridescence, or fine pinholes/islands most evident in oblique/raking views; no change after cleaning of exposed faces (Non-Invasive Reveal).
• Often distributed irregularly; may occur with other cavity issues (e.g., internal haze, spacer-edge phenomena).

Location / access (primary):

• Use surface numbering to identify #2/#3. Demonstrate between-pane by fixed parallax (feature stays fixed relative to its reflection as the observer moves). CAT-5 by location when confirmed.

Surface-catch class (MSRT):

• Not determinative for a cavity-face condition. MSRT applies to exposed faces only and is a single, non-marring pass used to support classification-not acceptance.

Inspection environment / reveal controls:

• Perform Non-Invasive Reveal (clean & dry) on the exposed face(s) before evaluation; if the cue persists, it supports a cavity location. Acceptance pertains to the exposed surface under evaluation.

Viewing / lighting:

• Apply VIS geometry: 12 / 36 / 72 in; normal incidence + oblique sweep (~60°-120°) under raking light to capture sheen/color change and patch boundaries.

• CAT-5 - Out of scope for in-place restoration when the anomaly resides on #2/#3 (between panes). Document and refer per project protocol (manufacturer/warranty/replacement). Note: For worked, exposed coated faces, VIS-A prohibits coating anomalies at acceptance (context: ASTM C1376), but that acceptance requirement does not apply to cavity-face anomalies.

• No accessible surface-relief reading on the exposed face; numeric depth is not applicable. Classification is appearance + location only.

• vs. Coating rub/patchiness on the worked exposed face (Co-family): Worked-face coating anomalies are disallowed at acceptance (VIS §6.2.e); cavity anomalies are between panes (fixed parallax) and CAT-5.
• vs. Exterior/interior residue films (R-family): Face-side films respond to Non-Invasive Reveal; cavity anomalies do not.
• vs. Internal volatile fog/haze (A.01.01): Haze presents as a diffuse veil; coating corrosion shows patchy/color change with coating-like boundaries. Use parallax and perimeter context to separate.

• Photo set (VIS): 12 / 36 / 72 in, normal + oblique, with raking; include frames that show patch boundaries and at least one parallax sequence demonstrating a between-pane cue.
• Forms: Record pane ID; surface numbering (#1-#4; laminate-internal); worked surface Y/N; functional coating present on worked surface? (Y/N/Unknown); reveal status; lighting/time; geometry checklist.
• Narrative split: “Cavity-face functional-coating anomaly on #2/#3; CAT-5 by location. VIS-A coating acceptance (no anomalies on worked coated surfaces) does not apply to cavity faces; refer per protocol.”

Attempting to “correct” a cavity coating anomaly on the exposed face risks creating a worked region (visible transition edge) that VIS disallows at acceptance for CAT-0...CAT-4. Confirm parallax and reveal status before any action.

• A.01.05 Low-E/Functional-Coating Appearance Change (Cavity #2/#3) - Patchy/iridescent coating appearance between panes, verified by fixed parallax; no change after Non-Invasive Reveal of exposed faces; MSRT not applicable to cavity face. CAT-5 (out of in-place scope by location). Documented per VIS geometry; refer per project protocol.