DSS-M.03.02 — Edge Gross Chipping / “Clamshell”

Gross edge chipping (“clamshells”) are discrete, larger shell-type fractures at or near the perimeter, typically from impact, improper handling, or stress at drilled/notched features. Classification is appearance-only per VIS; restoration methodology is out of scope. Inspect under VIS lighting/geometry and record surface numbering and worked-surface status on Forms:

• Crescent or shell-shaped voids at the arris/edge; may expose bright, rough fracture facets.
• Can propagate from hardware holes/notches; sometimes accompanied by short radial micro-cracks.
• Highly visible in raking light; often apparent at standard view once size increases. (See VIS geometry & raking use.)

Surface-catch class (MSRT)

• Clear detect at chip perimeter; perform one light, non-marring pass only to sense relief (SC-2). On coated faces, prefer polymer stylus or rely on visual/location cues per VIS §5.5.

Visual signature

• Rough chip flanks with bright, irregular fracture edges; may include pits/craters adjacent to the edge land or hole perimeter. (Chip-flank/rough-edge morphology is determinative for escalation from minor edge nicks.)

Viewing/lighting

• Evaluate at 12 / 36 / 72 in using normal incidence + oblique sweep (~60°-120°) with raking light; surfaces clean/dry (VIS §5).

Location/access.

• Log pane ID and surface numbering (#1-#4; laminate-internal) on forms; acceptance pertains to the exposed surface being evaluated. If fixed parallax indicates a between-pane cue, classify CAT-5 and refer.

Assign category by appearance cues + MSRT (not by intent to repair):

• CAT-2 → CAT-3 (lower bound): Larger, shallow shell with slight-clear catch and relatively clean flanks; visible primarily in raking light at close/standard view. Indicative depth: ~10-40 μm.
• CAT-3 (typical): Pronounced clamshell(s) with clear catch; rough, bright chip flanks; noticeable at standard view. Indicative depth: ~40-100 μm.
• CAT-4 (upper bound): Deep/extended shelling, multiple chips with secondary pits/craters or short cracks; strong catch; clearly visible at standard & wide-field views. Indicative depth: ~100-250 μm+.
• CAT-5 (by location/condition): Any case with through-thickness cracking, moving pane in frame, or between-pane/inaccessible location → out of in-place scope; document and refer.

Depth bands are indicative to anchor the spectrum for VIS-DA; assign CAT by visual/morphology + MSRT under VIS conditions.

• vs. Edge micro-chipping (M.03.01): Minor edge nicks are small, isolated, and may lack bright rough flanks; gross clamshells show larger shell faces with pronounced, bright fracture edges and clear catch.
• vs. Factory edge finishes (P.03.01 / P.03.02): Seamed/arris bands and edge grind/polish patterns are uniform, edge-bound, and read SC-0 on the face; they do not present discrete chip flanks or pits.
• vs. Drill/slot exit lip (P.03.04): A continuous exit-side burr/lip is a manufacturing artifact at hole/slot perimeter; escalate only if discrete face-side chips propagate from the exit.

• Photo set (VIS): 12 / 36 / 72 in, normal + oblique; include raking macros of chip flanks and at least one context frame showing the edge location (or hole/slot) and absence/presence of a worked perimeter.
• MSRT result: Record SC class (typically SC-2 “clear”); one pass only; non-marring; polymer stylus preferred on suspected coated faces.
• 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; transition edges and chip-flank morphology remain disqualifying at acceptance for CAT-1...CAT-4; structural/inaccessible → CAT-5 and refer.

• M.03.02 Edge Gross Chipping / Clamshell - Discrete shell-type edge loss at [edge/arrises or hole/notch], MSRT = SC-2 (clear) with bright, rough chip flanks; visible at [12/36/72 in per VIS]. Classify CAT-[3/4] by morphology under VIS-DA. If fixed parallax indicates between-pane location or if through-thickness cracking is observed, record CAT-5 and refer per project protocol.