DSS-Co.02.03 — Local Coating Discontinuity (Pyrolytic Hard-Coat)

Local coating discontinuity (pyrolytic) is an appearance change confined to pyrolytic (hard-coat) functional coatings where the deposited film exhibits a localized reduction in thickness, skip/void, or density change. It presents as a spot, small island, short streak, or patch with distinct sheen/color shift relative to surrounding coated areas. The phenomenon is planar within the coating and is generally non-tactile. Classification is appearance-only per VIS (method-agnostic). Inspect after Non-Invasive Reveal under VIS lighting/geometry; record surface numbering and worked-surface status.

Face identification is critical. Pyrolytic hard-coats commonly reside at #2 in IGUs (or #1/#4 by design). Confirm coated face before classification.

• Discrete spot/island (few mm to ~50 mm), short streak, or small patch with contrast shift (brighter/duller, warmer/cooler) vs. adjacent coating.
• Boundary can be sharp (abrupt film change) or soft/feathered (density gradient).
• May repeat at similar position across multiple lites in a lot (process-linked), or appear isolated (contact/handling during hot pass).

Surface-catch class (MSRT)

• SC-0 typical (planar optical change within coating).
• SC-1 localized only if a minute micro-imprint exists (e.g., particulate contact imprint).
• Perform one light, non-marring pass on a small revealed test patch; polymer stylus only on suspected coated faces. MSRT supports classification only; do not abrade the coating.

Visual signature

• Planar, non-grooved patch; no chip-flank sparkle, no pits/fused nodules.
• Color/shear change becomes more apparent in oblique sweep; under broad specular, the discontinuity outlines as the reflection “flashes.”
• If intra-lot repetition exists at consistent coordinates, favors intrinsic deposition/transport origin.

Viewing / lighting

• Evaluate clean & dry at 12 / 36 / 72 in, normal and oblique sweep (~60°-120°); raking to read boundary; broad specular to gauge color/shear change. Record distances/angles in-frame.

Location / access

• Record pane ID and surface numbering (#1-#4; laminate-internal). If on #2/#3 (IGU interior), it is inaccessible in place → CAT-5 by location (classification remains Co.02.03).

Mechanism cue (context)

• Hot deposition skip/variation, transient contamination on support, or contact imprint during hot transport; absence of field indicators (no runs/cream swirls, no scoring).

Assign CAT by visibility at acceptance geometry and MSRT.

• CAT-1 (Benign / non-relief): Small faint spot/streak legible mainly at oblique/raking; SC-0. Indicative relief: 0-10 μm (optical only).
• CAT-2 (Light): Discernible discontinuity at standard distance in certain lighting; SC-0 (or SC-1 localized if micro-imprint). Indicative relief: ~10-40 μm (apparent optical).
• CAT-3 (Moderate): Pane-noticeable patch at standard distance affecting uniformity over >0.5% of view area; SC-0/SC-1. Indicative relief: ~40-120 μm (apparent optical).
• Reclassify when: Parallel periodic bands → Co.02.01 Roller pickup; localized sheen shift tied to wipe arcs → Co.02.02 Rub/Scuff; linear grooves with chip flanks → M.01 Scoring; ring/run/halo chemistry → Ch.01/Ch.03; fused metallic peppering → Th.01.02.
• CAT-5 (by condition/location): Between-pane/inaccessible or coating-side constraints preclude compliant presentation → CAT-5.

CAT is appearance-based; acceptance is separate under VIS-A at 12/36/72 in. Do not abrade coated faces to “force” a response.

• vs. Sputtered low-E pinholes/islands (Co.01.03): Sputtered defects often show fine pinholes or color islands without hot-transport context and may be lot-wide but non-periodic; pyrolytic discontinuity often links to hot handling or specific line position.
• vs. Mineral/chemical spots (Ch family): Chemical spots show ring/rim, runs, or micro-texture (SC-1/2); Co.02.03 is planar, SC-0, without wetting geometry.
• vs. Mechanical pad trails (M.02): Abrasion trails show directional texture and SC-1 over a path; Co.02.03 is localized and non-directional at micro-scale.
• vs. Spandrel/back-paint anomalies (Co.04): Spandrel issues present on back-painted surfaces with opacity differences; Co.02.03 is on a functional hard-coat.

• Photo set (VIS): 12 / 36 / 72 in, normal + oblique; raking macros showing boundary; overview frames documenting size and position. Record distance/angle in-frame.
• Face ID + MSRT. Confirm coated surface; MSRT (polymer stylus only) on revealed patch records SC-class (SC-0 typical; SC-1 localized if present).
• Lot/replication check. Inspect adjacent lites for coordinate/shape repetition to support intrinsic origin.
• 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: Post-restoration acceptance per VIS-A §6; classification ≠ acceptance. Coated-face appearance rules apply per VIS §6.2.e when the worked surface is the functional coating.

• Co.02.03 Local Coating Discontinuity (Pyrolytic) - Discrete spot/streak with planar sheen/color shift on surface #___ (pyrolytic hard-coat confirmed); MSRT (polymer): SC-0 [SC-1 localized if micro-imprint]; visible at [12/36/72 in] under VIS geometry. Morphology: localized coating density/continuity change, no chip-flank grooves, no pits/runs. Classification: CAT-[1/2/3] by visibility; reclassify per notes if roller-pitch, rub/scuff, mechanical scoring, chemical, or spandrel indicators dominate; CAT-5 if between-pane or coating-side constraints preclude in-place work. Forms + photo set attached; acceptance per VIS-A §6.