DSS-Co.04.03 — Back-Paint Adhesion Loss Islands

Back-paint adhesion loss islands are localized detachments (adhesive or cohesive) within an opaque/semi-opaque back-coating on the non-viewable side of glass (e.g., spandrel paint, back-coated vision bands, ceramic frit overcoats). From the viewing face they present as duller/darker or brighter windows, contour-edged islands, or blisters; in advanced states they may flake, crescent at edges, or show voids at corners, fastener points, or rails. The defect is behind the glass and non-tactile from the viewing side. Classification is appearance-only per VIS (method-agnostic). Inspect after Non-Invasive Reveal at the viewing surface under VIS lighting/geometry; record surface numbering and worked-surface status.

System identification is critical. Confirm coating type (organic back-paint vs. ceramic frit), location (commonly #2 or #4), and vision vs. non-vision intent.

• Irregular “islands” or lobed patches with sharp/feathered boundaries; may show edge crescenting where paint lifts from glass.
• Blister domes (sub-millimeter to several millimeters) that change contrast with oblique sweep or light grazing.
• Edge-origin is common: along gasket/rail lines, fastener penetrations, mask/paint stops, splice joints, or thermal bridges.
• In severe cases, flaked paint voids expose clear glass through the spandrel field.

Surface-catch class (MSRT)

• At the viewing (glass) surface: SC-0 (planar defect behind the glass).
• Do not perform MSRT on the back-coating face in situ. MSRT supports classification only on the viewing surface.

Visual signature

• Contour-bounded islands/blisters; no chip-flank sparkle, no grooves, no pits on the viewing face.
• Parallax confirms behind-glass location; islands maintain position relative to reflections as the observer moves.
• Propagation cues: islands often grow inward from edges/corners or along hardware contact zones.

Viewing / lighting

• Evaluate clean & dry at 12 / 36 / 72 in, normal and oblique sweep (~60°-120°); raking enhances island outlines and blister domes; ambient back-lighting highlights clear exposures/voids. Record distances/angles in-frame.

Location / access

• Record pane ID and surface numbering (#1-#4; laminate-internal). If the anomaly resides on #2/#3 (IGU interior) or otherwise non-exposed back-coat, it is inaccessible in place → CAT-5 by location (classification remains Co.04.03).

Mechanism cue (context)

• Adhesion failure due to surface prep contamination, incompatible cleaners/solvents from behind, plasticizer/chemical migration from adjacent materials, UV/thermal cycling, moisture ingress, or mechanical shear at supports. Ceramic frit generally has excellent adhesion; similar “island” presentations on frit often implicate over-coats or interposed layers, not the frit itself.

Assign CAT by visibility at acceptance geometry and areal extent/progression (from the viewing side). Depth values below are apparent optical, not substrate relief.

• CAT-1 (Benign / non-relief): Few, small islands/blisters (<5 mm), legible mainly at oblique/raking; SC-0 viewing surface; no edge propagation.
• CAT-2 (Light): Scattered islands visible at standard distance; cumulative affected area ≤0.5% of the field; SC-0 viewing surface.
• CAT-3 (Moderate): Clusters/bands or edge-propagating islands affecting perceived uniformity >0.5% or along critical sightlines; localized clear voids may be present; SC-0 viewing surface.
• Escalation / reclassify: If front-face chemical rings/runs coexist → also classify Ch family; if front-face grooves/pits present → M/Th families.
• CAT-5 (by condition/location): Between-pane/back-coat face inaccessible, or system constraints preclude in-place correction → CAT-5.

CAT is appearance-based; acceptance is separate under VIS-A at 12/36/72 in. Back-paint adhesion failures are commonly producer/system issues and outside in-place restoration scope when on non-exposed faces.

• vs. Pinholes/holidays (Co.04.02): Pinholes are point-voids with sharp, tiny dots; adhesion-loss islands are larger lobed patches or blisters with contoured boundaries.
• vs. Spandrel mottle (Co.04.01): Mottle is cloud-like density variation without discrete boundaries/blister domes.
• vs. Front-face chemistry (Ch): Chemical attack shows rings/runs/etch at the viewing surface and can yield SC-1/2; Co.04.03 remains SC-0 on the viewing face.
• vs. Delamination in laminates (A.02.06): Laminate delamination occurs within plies/interlayer, often with edge whitening/bubbles mid-thickness; back-paint islands are on the rear coating, not within laminate plies.

• Photo set (VIS): 12 / 36 / 72 in, normal + oblique; raking macros across island edges/blisters; back-lit frames for clear voids; document edge origin if present. Record distance/angle in-frame.
• Face/System ID. Confirm back-paint/frit face and system build (submittals/shop drawings). Note adjacent gaskets/rails/adhesives that may contribute.
• MSRT (viewing surface only). Record SC-0 to distinguish from front-face mechanical/chemical attack.
• Lot/replication check. Survey adjacent units for pattern repetition or edge-progression to support producer/system origin.
• Forms: Pane ID; product family & surface numbering; worked surface Y/N; functional/back-paint coating 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. Non-exposed coating faces are typically outside in-place restoration scope.

• Co.04.03 Back-Paint Adhesion Loss Islands - Contour-bounded islands/blisters behind glass on surface #___ (back-paint/frit system confirmed); MSRT (viewing face): SC-0; visible at [12/36/72 in] under VIS geometry and [oblique/back-lit]. Morphology: localized adhesion/cohesive failure, possible edge-origin propagation, no chip-flank grooves/pits on viewing face. Classification: CAT-[1/2/3] by visibility/extent; CAT-5 if between-pane/back-coat face inaccessible; reclassify only if viewing-face mechanical/chemical indicators are present. Forms + photo set attached; acceptance per VIS-A §6.