DSS-P.01.01 — Roller Wave (Periodic Flatness Deviation)

A periodic flatness deviation characteristic of heat-treated flat glass that appears as bands/undulations in reflection or transmission. It is a factory feature of the product, not a field-induced surface relief defect. For measurement background on optical/roll-wave distortion in heat-treated flat glass, see ASTM C1651 (informative reference noted in VIS).

• Alternating light/dark bands visible across reflections (e.g., mullions, horizon lines), sometimes more apparent at oblique angles.
• Uniform across large areas of a lite or series of lites from the same run; not localized like scratches or pits.
• Does not respond to Non-Invasive Reveal (cleaning) and shows no surface catch. Use VIS inspection lighting/geometry to visualize consistently.

• Surface catch (MSRT): none (PVΔ as “damage” ≈ 0 at the surface). Perform one light non-marring pass only to confirm absence of relief.
• Morphology: global/periodic flatness effect; no chip flanks, no pits, no modeled micro-texture.
• Visibility geometry: evaluate under VIS Section 5-raking/low-angle light as needed, with 12/36/72 in distances and normal + oblique sweep.

• Not field damage. Do not classify as CAT-1...CAT-4. Roller wave is a processing feature referenced here to prevent misclassification; acceptance of factory flatness/optical quality is governed by the applicable product standards/project specs, not by VIS (which governs post-restoration acceptance).

• N/A as surface relief. Roller wave is flatness/optical deviation; at the glass surface it does not present as a localized relief feature detectable by MSRT. If factory flatness or optical distortion must be quantified, see ASTM C1651 background as noted in VIS (informative).

• Versus micro-abrasion / pad trails (M.02.01): abrasion presents localized haze or directional swirls and may show slight catch; roller wave is global/periodic and non-tactile.
• Versus over-polish/burnish (M.02.04): burnish is a localized appearance change (often directional) and may show a transition edge; roller wave has no transition edge and extends broadly.
• Versus modeled micro-texture (chemical etch): chemical etch shows non-linear micro-texture strongest in raking light and can exhibit slight/clear catch at severity; roller wave remains non-tactile and periodic.

• Photo set at 12 / 36 / 72 in under VIS geometry; include one frame with straight-line reflection (string line, mullion, horizon) to show periodicity. Note MSRT = none. Record pane IDs and apply surface numbering conventions.

• Attempting corrective “spot work” on roller wave-treating it like a scratch field-can introduce visible worked zones and transition edges. VIS explicitly separates classification from acceptance and requires non-invasive pre-inspection cleaning only.

• “Observed roller wave (factory flatness feature) presenting as periodic reflective banding across lite(s). No surface catch (MSRT). Condition is a processing feature; not classified as field damage under DSS. Inspection performed per VIS §5 (lighting/viewing).”