DSS-P.04.03 — Spandrel Opacity Variation (system tolerance)

Spandrel glass uses an opaque back-paint or ceramic-frit system to mask building elements. Minor opacity/tonal variation is a system/production tolerance (paint film build, substrate/cavity effects) and is not a worked-surface defect. Evaluate using the VIS inspection lighting/geometry; post-restoration acceptance for any worked area follows VIS and must not be conflated with factory/product acceptance for spandrel systems.

• Low-contrast “mottle/cloudiness” visible through the exterior lite over pane-scale areas; increases/decreases with angle/raking.
• Subtle panel-to-panel tone shift; uniform across a lite without a discrete, local boundary.
• No tactile relief on the exposed surface after reveal/dry. (Use the VIS geometry-12/36/72 in; normal + oblique sweep; raking light.)

• Surface-catch class (MSRT): SC-0 (none). One light, non-marring pass per VIS §5.5; do not abrade or repeat. On suspected coated faces, prefer a polymer stylus or rely on visual cues. MSRT supports classification only.
• Visual signature: Pane-scale opacity/tonal non-uniformity without a local “worked” perimeter, transition edge, chip flanks, or pits/craters.
• Viewing/lighting: Inspect at 12 / 36 / 72 in, normal incidence and oblique sweep (~60°-120°) under raking light; surfaces clean & dry (non-invasive reveal).
• Location/access: Log pane ID & surface numbering (#1-#4; laminate-internal) on forms; acceptance pertains to the exposed surface being evaluated.

• Not field damage. If observation confirms pane-scale opacity variation with SC-0 and no worked boundary, record: “Design/System Feature - Not Surface Damage (outside CAT-1...CAT-4).” Classification remains appearance-only; do not assign a CAT for factory/system tolerances.
• Escalate / reclassify when localized anomalies are present:
• Pinholes/holidays or adhesion-loss islands in the back-paint → Co.04.02 / Co.04.03 (coating defects on spandrel). (Worked-surface coating anomalies are not permitted at acceptance on coated faces; apply VIS §6.2.e.)
• Surface rub/patchiness on an exterior coated face (non-spandrel functional coat) → Co.01/Co.03 and classify by CAT per VIS (appearance-only).
• Between-pane look-alike (fixed parallax in an IGU) → CAT-5 (out of in-place scope by location); refer per project protocol.

Opacity variation is a visual/optical system attribute; no tactile relief at the exposed surface (SC-0). Numeric depth is not applicable; classification relies on MSRT class + morphology and VIS viewing geometry.

• vs. Coating anomalies (worked-surface): Coating rub/patchiness is localized, may show a worked boundary, and is disallowed at acceptance on coated faces (VIS §6.2.e). Spandrel opacity variation is pane-scale/system-level with no worked perimeter.
• vs. Chemical etch or abrasion fields: Etch/abrasion present modeled micro-texture or directionality and can escalate to SC-1/SC-2; spandrel mottle remains SC-0 and perimeter-free at the exposed surface under VIS geometry.
• vs. Decorative glazing texture: Patterned/textured glass has intentional surface relief (design). Evaluate per VIS geometry and decorative-glazing viewing guidance (NGA FB67-20, informative) rather than treating as opacity variation.

• Photo set (VIS): 12 / 36 / 72 in, normal + oblique; include raking frames that show pane-scale tone/mottle, and at least one context frame establishing lack of a local worked boundary.
• MSRT result: Record SC-0 (one pass only; non-marring; polymer stylus on suspected coatings).
• 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: VIS governs post-restoration appearance (no transition edge/directional patterning in worked areas at required views). Factory/system tolerances for spandrel are governed by product standards/project specs-do not conflate.

Attempting localized “spot-correction” of inherent spandrel mottle can create a worked region with a visible transition edge, which VIS disallows at acceptance (CAT-0...CAT-4). Keep classification appearance-only for system tolerances; only reclassify when true coating defects or worked-surface anomalies exist.

• P.04.03 Spandrel Opacity Variation (System Tolerance) - Pane-scale opacity/tonal non-uniformity observed at VIS geometry; MSRT = SC-0 (no surface relief). No transition edge or chip-flank/pit morphology on the exposed face. Recorded as design/system feature; not categorized as surface damage under VIS-DA. If localized pinholes/adhesion-loss islands or worked-surface coating rub/patchiness are present, classify under Co.04.02 / Co.04.03 or Co.01/Co.03 by CAT per VIS; if between-pane cues are confirmed, record CAT-5 and refer per project protocol.