A Category 1 surface contaminant that appears as a circular or partial-ring mark where a suction cup contacted the glass during lifting, handling, transport, or installation.
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Meaning and boundaries
Treat the suction-cup mark as surface contamination first. If cleaning reveals a scratch, coating change, or other remaining substrate damage, classify that separate condition by its own morphology and repairability.
Why it matters in glass restoration
Recognizing the mark as Category 1 directs the technician to contaminant removal before considering abrasion or polishing and supports better cup-cleaning and handling practices.