DSS-Ch.06.01 — Silane / Siloxane Migration Halo

Silane/siloxane migration halo is an appearance change on glass resulting from penetrating water-repellent treatments (silane/siloxane) applied to adjacent porous materials (masonry/concrete/stone). During application, overspray, vapor phase, or capillary contact/weep can deposit organosilicon films on the glass, producing optical halos/veils and, with UV/heat/soiling, tenacious films that may leave very shallow micro-texture after long dwell. Classification is appearance-only per VIS (method-agnostic). Inspect after Non-Invasive Reveal under VIS lighting/geometry; record surface numbering and worked-surface status. Handle active chemical work zones per site safety.

• Halo or band parallel to masonry joints, sills, copings, drip edges, or sealant interfaces; may trace weep paths or roller/spray edges.
• Iridescent or greasy-sheen veil in specular view; soft edge on the glass side, sharper edge at the masonry boundary; may accumulate soiling preferentially over time (“dirty halo”).
• After reveal, portion of the veil persists; in stronger/aged cases, very fine modeled micro-texture may be noted at raking.

Surface-catch class (MSRT)

• Frequently SC-0 (optical film only) on freshly contaminated glass.
• SC-1 (slight) may occur on aged/UV-baked halos where organosilicon residues cross-link with contaminants, leaving very shallow texture. SC-2 uncommon.
• Perform one light, non-marring pass on a revealed test patch only; polymer stylus if a functional coating is suspected on the worked face. MSRT supports classification only.

Visual signature

• Linear/curvilinear band coincident with treated substrate geometry (head/sill/jamb lines, parapets); soft interior, sometimes tide-line edge toward the glass field.
• No chip-flank sparkle (not mechanical scoring); no discrete pits/nodules (not hot-particle peppering).

Viewing / lighting

• Evaluate clean & dry at 12 / 36 / 72 in, using normal incidence and oblique sweep (~60°-120°); use raking light to resolve veil presence and any fine texture. Record distances/angles in-frame.

Location / access

• Record pane ID and surface numbering (#1-#4; laminate-internal). If fixed parallax indicates between-pane film (IGU), classify CAT-5 by location (out of in-place scope) and refer.

Mechanism cue (context)

• Recent or historic water-repellent treatment on adjacent masonry/stone, presence of sprayers/rollers, masking lines, or contractor notes; weather window during application (wind, sun).

Assign CAT by visibility impact and MSRT after controlled reveal on a small representative area. Depth values are indicative-field measurement not required.

• CAT-1 (Benign / non-relief): Optical halo/veil only, SC-0 on clean substrate; visible primarily at certain angles/raking; limited at standard view. Indicative relief: 0-10 μm (optical).
• CAT-2 (Light): Persistent thin film with SC-1 at a revealed test patch (aged case); limited impact at standard view; edges track substrate geometry. Indicative relief: ~10-40 μm.
• CAT-3 (Moderate): Broader banding/halo legible at standard distance with SC-1 to SC-2 in aged regions; often co-located with soil accumulation. Indicative relief: ~40-120 μm.
• CAT-4 (Severe): Rare for silane/siloxane alone; if pronounced matte fields or widespread cross-linked texture occur, consider mixed chemistry (alkali + organosilicon + UV/soiling) and re-evaluate under applicable DSS. Indicative relief: ~120-300 μm+.
• CAT-5 (by condition/location): Between-pane/inaccessible by parallax, integrity indicators (active cracks/pane movement), or confirmed functional-coating loss on the surface to be worked → CAT-5.

CAT is appearance-based; acceptance is separate under VIS-A at 12/36/72 in. Do not abrade to “force” film removal during classification.

• vs. Hydrophobic coating mismatch halo (Ch.06.02): Coating mismatch halos are on intentional glass coatings and show water-behavior edges unrelated to masonry geometry; silane migration halos align with treated substrate lines/weep paths.
• vs. Efflorescence-associated attack (Ch.02.03): Efflorescence presents feathered salt blooms and grainy etch beneath; silane halos read oily/iridescent veil with SC-0/SC-1 and less granular raking response.
• vs. Mineral staining/etch (Ch.03): Mineral issues track spray arcs/rings and may show ring halos; silane halos align with substrate treatment geometry and often soil-load preference along the band.
• vs. Residue films (R-family): General detergents/soot films lack strong geometric correlation to treated masonry lines and often clear more uniformly at reveal.
• vs. Coating anomalies (Co-family): Functional coating rub/patchiness is tied to coated faces and manufacturing/handling; migration halos originate from post-installation chemical treatment on adjacent porous materials.

• Photo set (VIS): 12 / 36 / 72 in, normal + oblique; include raking macros of the halo edge and interior veil; add context frames showing treated masonry/stone, masking lines, weep paths. Record distance/angle in-frame.
• MSRT result: One light, non-marring pass on a clean test patch within the halo; record SC-class (SC-0/SC-1/SC-2). Polymer stylus if a coating is suspected.
• 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.

• Ch.06.01 Silane/Siloxane Migration Halo - Linear band/halo aligned with [masonry/stone treatment line or weep path] on surface #___; post-reveal test patch shows [SC-0/SC-1]; visible at [12/36/72 in] under VIS geometry. Morphology: oily/iridescent veil, soft interior, tide-line edge; no chip-flank sparkle, no discrete pepper. Classification: CAT-[1/2/3/4] by relief/visibility; CAT-5 if between-pane, integrity cues, or coating-side loss on the surface to be worked. Forms + photo set attached; acceptance per VIS-A §6.