DSS-Co.04.02 — Pinholes / Holidays (Spandrel & Back-Paint Systems)

Pinholes/holidays (spandrel/back-paint) are discrete, point-like voids or ultra-thin spots in an opaque or semi-opaque coating applied to the non-viewable side of the glass (e.g., spandrel back-paint, ceramic frit). From the viewing face they present as tiny bright/clear dots (transmission) or high-reflectance specks (reflection). The defect is planar behind the glass and non-tactile at the viewing surface. 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.

• Isolated or clustered clear points (0.1-2 mm typical), sometimes constellated along dust trails or application edges.
• Under back-light: points appear bright relative to the field; under specular reflection: points sparkle.
• Clusters may align with application direction, screen edges, masking lines, or particulate contamination sites.

Surface-catch class (MSRT)

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

Visual signature

• Discrete point voids with sharp boundaries; no chip-flank sparkle, no grooves, no pits on the viewing face.
• Size distribution is narrow within a cluster; repeatability across units suggests process origin (e.g., screen pinhole, dust seeds, solvent pop).

Viewing / lighting

• Evaluate clean & dry at 12 / 36 / 72 in, normal and oblique sweep (~60°-120°). Use back-lit frames (ambient interior lighting) and broad specular to make points legible. 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.04.02).

Mechanism cue (context)

• Particulate contamination at paint/frit application (masking dust, oil), screen printing voids, solvent pop, insufficient wet film or edge draw-down, post-cure adhesion loss at point seeds.

Assign CAT by visibility at acceptance geometry and count/density of pinholes. Depth values are apparent optical, not substrate relief.

• CAT-1 (Benign / non-relief): Few, very fine pinholes legible mainly in oblique/back-lit conditions; SC-0 viewing surface. Indicative optical relief: 0-10 μm (apparent).
• CAT-2 (Light): Scattered pinholes visible at standard distance under common lighting; SC-0; aesthetic but limited area. Indicative optical: ~10-40 μm.
• CAT-3 (Moderate): Clusters/bands of pinholes affecting perceived uniformity across >0.5% area or along critical sightlines; SC-0. Indicative optical: ~40-120 μm.
• Reclassify when: If points correspond to front-face pits or fused nodules → Th.01 hot particle; if ring/halo chemistry appears on viewing face → Ch family; if linear grooves exist → M.01.
• CAT-5 (by condition/location): Between-pane/back-paint 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. Spandrel/back-paint pinholes are commonly producer/system governed and outside in-place restoration scope when on non-exposed faces.

• vs. Mineral peppering (Ch.03): Mineral peppering shows ring/flow context and may be SC-1/2; Co.04.02 pinholes are planar behind glass and SC-0 at the viewing surface.
• vs. Hot particle embed (Th.01.02): Hot particle shows fused hemispheres/craters on the exposed face; Co.04.02 points are clear windows through an opaque back-coat.
• vs. AR/low-E pinholes (Co.01.03): Functional low-E pinholes occur on vision coatings and affect interference color; spandrel pinholes occur in opaque fields and read as bright dot windows.
• vs. Dust on glass: Loose dust moves/lifts with reveal; pinholes persist at fixed coordinates.

• Photo set (VIS): 12 / 36 / 72 in, normal + oblique; back-lit frames to make clear points evident; raking macros verifying smooth viewing surface. Record distance/angle in-frame.
• Face/System ID. Confirm spandrel/back-paint face and system build (submittals/shop drawings).
• MSRT (viewing surface only). Record SC-0 to distinguish from front-face mechanical/chemical attack.
• Lot/replication check. Survey adjacent lites for coordinate repetition (supports producer-intrinsic 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.04.02 Pinholes / Holidays (Spandrel/Back-Paint) - Discrete clear/bright points through opaque back-coat on surface #___ (system build confirmed); MSRT (viewing face): SC-0; visible at [12/36/72 in] under VIS geometry and [back-lit/specular]. Morphology: point-voids, no chip-flank grooves, no surface pits on viewing face. Classification: CAT-[1/2/3] by visibility/density; CAT-5 if between-pane/back-paint face inaccessible; reclassify only if front-face mechanical/chemical indicators are present. Forms + photo set attached; acceptance per VIS-A §6.