DSS-P.01.03 — Quench / Anisotropy Patterning (polarization-visible)

A spatial variation in optical response (anisotropy) characteristic of heat-treated glass caused by non-uniform cooling in the quench. It presents as bands, mottling, or “zebra/leopard” tonal shifts that are most evident in reflection/transmission at oblique angles and may be accentuated by polarized viewing. It is a factory feature of the product-not a localized surface-relief defect. For measurement/optics background related to heat-treated glass distortion phenomena, VIS cites ASTM C1651 as informative context.

• Non-directional, pane-scale tone/brightness shifts; may appear banded or patchy across the lite.
• Most apparent at oblique sweep under raking/low-angle light; can be seen at normal incidence on some façades; visibility varies with sky conditions and reflections. (Observe using VIS geometry.)
• Not localized like a scratch/pit and does not respond to non-invasive reveal (cleaning).

Surface-catch class (MSRT):

• SC-0 (none). Perform one light, non-marring pass only to confirm no tactile relief; do not abrade or repeat passes.

Visual signature:

• Pane-scale mottle/banding without a transition edge; no chip flanks, no pits/craters, no modeled micro-texture typical of chemical etch. Evaluate at 12/36/72 in with normal + oblique sweep under VIS lighting.

Location/access:

• Whole-lite appearance feature; pertains to the exposed surface being evaluated for observation only.

• Not field damage. Quench/anisotropy is a processing/optical feature and is not categorized as CAT-1...CAT-4. When observation confirms SC-0 with pane-scale signature and no local morphology, record: “Processing Feature - Not Surface Damage (outside CAT).” If the apparent pattern is inside an IGU cavity or otherwise inaccessible, document fixed parallax and record CAT-5 (out of in-place scope by location).

Not applicable as a local surface-relief quantity. Anisotropy is an optical (stress/retardation) phenomenon from heat-treat; no micrometre relief is detected at the exposed surface by MSRT (SC-0). For broader heat-treated optical context, VIS references ASTM C1651 (informative).

• vs. Roller wave (P.01.01): Roller wave shows periodic banding (short wavelength) tied to roll contact; anisotropy can be mottled/banded but is polarization-sensitive and not periodic. Both remain SC-0 (non-tactile).
• vs. Bow/warp (P.01.02): Bow/warp is global shape (straight lines bend smoothly); anisotropy is optical mottle/banding without uniform curvature. Both lack transition edges and surface catch.
• vs. Low-E coating rub/patchiness (Co.01.02): Coating rub produces localized sheen/color shifts and can create a worked boundary or directional scuffs. VIS acceptance prohibits coating anomalies on the worked surface; record coating presence in Forms:

• Photo set at VIS geometry: 12 / 36 / 72 in, normal + oblique; include a straight-line reflection (mullion/string line) where practical; note whether raking was used.
• MSRT result: Record SC-0; one pass only; no abrasion.
• Forms: Pane ID; surface numbering (#1-#4; laminate-internal); coating present Y/N/Unknown; non-invasive reveal completed (Y/N); lighting notes/time.

• Attempting localized “spot-work” on anisotropy can introduce a visible worked region and transition edge. VIS separates classification from post-restoration acceptance; do not conflate factory features with repairable surface defects.

• P.01.03 Quench/Anisotropy Patterning (Processing Feature) - Pane-scale optical mottle/banding observed at VIS geometry; MSRT = SC-0 (no surface relief). No localized transition edge or chip-flank morphology. Recorded as manufacturing optical feature; not classified as surface damage under VIS-DA. If pattern is within IGU cavity (fixed parallax), record CAT-5 and refer per project protocol.