DSS-M.07.02 — Through-Thickness Crack Propagation

A through-thickness crack is a continuous fissure that extends through the glass thickness (or is actively propagating toward full depth) and may branch, curve, or run under residual/operational stress. Any confirmed crack is an integrity indicator and is out of in-place restoration scope under VIS (CAT-5 by condition/location). Classification here is appearance-only; methodology is out of scope. Inspect under VIS lighting/geometry after Non-Invasive Reveal; record surface numbering and worked-surface status on Forms:

• Filament-thin, continuous line that remains visible under small viewpoint shifts; may mirror on opposite surface reflections due to depth.
• Can display branching (hackle), kinks, or arrest marks; may originate at edge/corner, hole/notch root, impact origin, or thermal hot spot.
• Frequently apparent at standard view; oblique/raking views clarify the origin and continuity.

Surface-catch class (MSRT)

• Do not pass a stylus across any suspected crack. If needed, one light, non-marring pass adjacent to the feature may document nearby surface relief (for context only). MSRT is auxiliary and never determinative for integrity.

Visual signature

• Unbroken, phase-stable line that can cross faint residues or micro-texture without interruption; may show tip sharpening in the propagation direction.
• Under raking light, crack edges do not exhibit consistent abrasive chip-flank sparkle typical of scratches; instead, they read as a dark/bright contrast that remains with small viewpoint changes.

Viewing / lighting

• Evaluate clean & dry at 12 / 36 / 72 in, using normal incidence and oblique sweep (~60°-120°) with raking light. Capture both specular and, where possible, transmitted-light views to confirm depth.

Location / access

• Record pane ID and surface numbering (#1-#4; laminate-internal). If fixed parallax indicates a between-pane or laminate-internal crack, it remains CAT-5 by location and must be referred (out of in-place scope).

Assign category by appearance + integrity:

• CAT-5 (default): Any confirmed through-thickness (or actively propagating) crack → Non-Repairable / Out of In-Place Scope. Document length, origin (edge/corner/hole/impact/thermal), and proximity to supports/hardware; refer per project protocol (e.g., replacement/manufacturer service).
• Reassign only if no crack is present:
• If the cue is an abrasive line (continuous score) with MSRT catch and chip-flank sparkle → classify under M.01 Linear scoring.
• If the cue is edge/penetration chipping without a continuous fissure → classify under M.03.01-M.03.04 or M.06.01 as appropriate.

CAT is governed by integrity/location for cracks; acceptance is evaluated separately under VIS §6.

• vs. Linear scratch/score: Scratches show abrasive edges and clear MSRT catch; cracks remain phase-stable, can cross faint films without losing continuity, and must not be stylus-tested.
• vs. Thermal stress crack (Th.03.01): Thermal origins often align with localized heating or solar hot-spot geometry; mechanism note may be added, but classification remains crack = CAT-5.
• vs. Star break (M.04.02): Star/bullseye networks are impact-origin crack systems; default CAT-5 by integrity.
• vs. Laminate-internal feature / IGU cavity artifact: Use parallax and reflection tracking; internal = CAT-5 by location even if not structurally active on the exposed face.

• Photo set (VIS): 12 / 36 / 72 in, normal + oblique, include raking macros that show continuous fissure and origin (edge, corner, hole/notch, impact). Add a context frame showing distance to edges/corners/hardware. Record distance/angle in-frame.
• MSRT note. If recorded, note adjacent SC-class only (do not cross the fissure); one light, non-marring pass; polymer stylus if a coating is suspected.
• Forms: Pane ID; surface numbering (#1-#4; laminate-internal); worked surface Y/N; functional coating on worked surface? (Y/N/Unknown); reveal status; lighting/time; geometry checklist; photos attached.
• Disposition. Mark CAT-5 for any confirmed crack. Note apparent stability (active tip vs. blunted), estimated length, origin, and nearest support/hardware. Refer per project protocol.

• M.07.02 Through-Thickness Crack Propagation - Continuous fissure observed on surface #___ under VIS geometry (oblique + raking), originating at [edge/corner/hole/notch/impact/thermal]. MSRT not performed across fissure; adjacent reading SC-[ ] noted for context. Classification: CAT-5 (integrity/location). Surface numbering recorded; parallax checked. Photo set + forms attached; acceptance per VIS §6 (separate).