DSS-A.01.06 — Breather / Altitude-Tube Staining Pattern (#2 / #3)

Characteristic staining or streaking patterns deposited on IGU cavity faces (usually #2 / #3) associated with breather/altitude-tube ports used during fabrication/shipping/altitude equalization. By location (between panes), these cues are not on an exposed worked face and are not addressable in place; classification is therefore location/condition-driven. This entry follows VIS surface numbering and between-pane verification by fixed parallax.

• Localized halos, arcs, or drip-like streaks emanating from or near the tube entry/sightline, commonly along the perimeter; tone may be translucent, slightly glossy, or matte.
• No change after Non-Invasive Reveal of the exposed faces; persists in identical position when viewed at different angles (i.e., parallax-fixed between the panes).

Location / access (primary):

• Identify faces via surface numbering (#1-#4). Demonstrate between-pane location by fixed parallax (feature remains stationary relative to its reflection as the observer moves). If confirmed, classify CAT-5 by location.

Surface-catch class (MSRT):

• Not determinative for a cavity-face cue. MSRT is for exposed faces only and is a single, non-marring pass to support classification-not acceptance. On the exposed face, record SC-0 (no relief) if checked.

Inspection environment / reveal controls:

• Perform Non-Invasive Reveal (clean & dry) on the exposed surface(s) before evaluation; if the cue persists unchanged, that supports a cavity origin. Do not use blades/abrasives/chemicals prior to classification.

Viewing / lighting:

• Apply VIS geometry: 12 / 36 / 72 in; normal incidence + oblique sweep (~60°-120°) with raking light. Include perimeter shots that show the cue’s relationship to the likely tube location.

• CAT-5 - Out of scope for in-place restoration when the staining resides on #2/#3 (between panes). Document and refer per project protocol (manufacturer/warranty/replacement).

• No accessible relief on the exposed face (SC-0 if checked). Apparent “depth” is within the cavity; numeric surface depth on the exposed face is not applicable.

• vs. Spacer smear/bleed (A.01.04): Spacer smear typically forms continuous bands parallel to the spacer; breather-tube staining often radiates from a point/port or short perimeter segment. Both are CAT-5 by location-document geometry and parallax.
• vs. Internal haze/volatile fogging (A.01.01): Fogging is a diffuse veil across a broader field; tube staining is localized with identifiable origin. Use parallax and perimeter context.
• vs. Face-side residue (R-family): Face films respond to reveal; cavity staining does not. Confirm with reveal and fixed parallax.

• Photo set (VIS): 12 / 36 / 72 in, normal + oblique, raking; include a parallax sequence and perimeter frames that show the tube/port adjacency.
• Forms: Record pane ID, product family & surface numbering (#1-#4; laminate-internal), worked surface Y/N, functional coating present on worked surface? (Y/N/Unknown), reveal status, lighting/time, geometry checklist.
• Narrative split: “Between-pane perimeter staining consistent with breather/altitude-tube origin on #2/#3; CAT-5 by location; refer per protocol.”

Attempting to “clean” a cavity artifact from the exposed face risks creating a worked region (visible transition edge), which VIS disallows at acceptance for CAT-0...CAT-4. Confirm reveal status and parallax before any action.

• A.01.06 Breather/Altitude-Tube Staining (Cavity #2/#3) - Localized perimeter staining consistent with tube/port origin; parallax-fixed between panes; no change after Non-Invasive Reveal; MSRT not applicable to cavity face. CAT-5 (out of in-place scope by location). Documented per VIS geometry; refer per project protocol.