DSS-Th.02.02 — Overheated Grinder/Belt Burn Line

An overheated grinder/belt burn line is a localized, elongated band produced when a powered abrasive (grinder, belt, pad, or wheel) is run against the glass (often inadvertently) long enough to generate frictional heat. The result is a tone/shine shift (and, at higher severities, modeled micro-texture/matte) along the tool path. Classification is appearance-only per VIS (method-agnostic). Inspect after Non-Invasive Reveal under VIS lighting/geometry; record surface numbering and worked-surface status on Forms:

• Linear/curvilinear band tracking tool travel, sometimes with a feathered head/tail and central hot core.
• In specular view: duller gloss or color/contrast shift vs. adjacent glass; in raking light: non-directional, modeled micro-texture within the band.
• May show light residue (rubber/compound) that clears at reveal, leaving the core burn band visible.

Surface-catch class (MSRT)

• SC-0 when effect is optical only (gloss/tone shift without relief).
• SC-1 (slight) where very shallow micro-texture is present; SC-2 (clear) is uncommon but possible on severe overheats approaching frosted appearance. Perform one light, non-marring pass (polymer stylus if a coating is suspected). MSRT supports classification only.

Visual signature

• Continuous band with soft boundaries; no discrete pits/craters and no chip-flank sparkle typical of scoring.
• Texture inside the band reads modeled (non-directional), not a swirl/web of abrasive scratches.

Viewing / lighting

• Evaluate clean & dry at 12 / 36 / 72 in, normal incidence and oblique sweep (~60°-120°) with raking light to resolve any micro-texture; document distances/angles in-frame.

Location / access

• Record pane ID and surface numbering (#1-#4; laminate-internal). If parallax demonstrates a between-pane look-alike, classify CAT-5 by location and refer per project protocol.

Mechanism cue (context)

• Nearby evidence of powered abrasives (handheld grinders, belts, polishers), belt tracking marks on adjacent finishes, or compound/rubber smear at band edges.

Assign CAT by appearance + MSRT + morphology (three-part cueing). Depth/relief values are indicative-no measurement required.

• CAT-1 (Benign/non-relief): Sheen/tone shift only; SC-0; visible primarily in raking at close/standard view. Indicative relief: ~0-10 μm (optical only).
• CAT-2 (Light): Subtle modeled micro-texture, SC-1; limited impact at standard view; boundaries remain soft. Indicative relief: ~10-40 μm.
• CAT-3 (Moderate): Clear detect (SC-2) with apparent modeled micro-texture at standard view; still no pits/craters, no chip flanks. Indicative relief: ~40-120 μm.
• CAT-4 (Severe): Pronounced matte/frosted lane from overheating/incipient devitrification; distinct at standard & wide-field views; no discrete pepper. Indicative relief: ~120-300 μm+.
• CAT-5 (by location/condition): Between-pane/inaccessible by parallax, integrity indicators (active cracks/pane movement), or confirmed coating-side 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 use MSRT to “probe” or alter surfaces.

• vs. Linear scoring (M.01): Scoring shows abrasive lines with chip-flank sparkle and SC-2 along edges; burn lines show modeled micro-texture/gloss shift with soft boundaries.
• vs. Torch proximity streak (Th.02.01): Torch bands align with a heat plume and may accompany soot films; belt/grinder burns track tool contact and often coincide with rubber/compound smears (removable).
• vs. Hot-particle peppering (Th.01.xx): Slag/sparks present discrete fused nodules or pits with bright rims; burn lines lack discrete pepper.
• vs. Residue films (R-family): Films clear at reveal and read SC-0; a persisting core band with SC-1/2 micro-texture indicates thermal burn.
• vs. Coating anomalies (Co-family): Coating rub/patchiness shows sheen/color change but - if on a worked coated surface - is not permitted at acceptance; confirm coating presence and apply VIS §6.2.e.

• Photo set (VIS): 12 / 36 / 72 in, normal + oblique, include raking macros resolving micro-texture within the band; add context frames showing tool path or nearby abrasive equipment. Record distance/angle in-frame.
• MSRT result: Record SC-class (SC-0/1/2) with one light, non-marring pass; polymer stylus 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: Post-restoration acceptance per VIS-A §6; classification ≠ acceptance. Coating-side anomalies on the worked surface remain disqualifying.

• Th.02.02 Overheated Grinder/Belt Burn Line - Localized heat-affected band on surface #___ with [SC-0/SC-1/SC-2], no pits/craters or chip flanks; visible at [12/36/72 in] under VIS geometry after Non-Invasive Reveal. Morphology: sheen/contrast shift ± modeled micro-texture; boundaries soft. Classification: CAT-[1/2/3/4] by cues; CAT-5 if between-pane/integrity or coating-side loss on the surface to be worked. Forms + photo set attached; acceptance per VIS-A §6.