Surface growth vs soot deposition
Texture, wetting and distribution help separate dark biological spotting from airborne particles.
Cold corners, window reveals, damp finishes and poorly ventilated surfaces
Cold framing lines, window edges and surfaces in particle-laden air
After repeated high humidity or persistent surface dampness
Builds gradually during heating seasons or combustion exposure
Speckled, patchy or soft growth that follows moisture-prone areas
Dry gray-black smudging that follows airflow or thermal patterns
Check texture, recurring moisture and whether the surface remains damp
Compare wipe texture, moisture history and distribution across cold lines
Dry wipeable film aligned with air movement and no moisture history
Soft or fuzzy material that regrows after damp conditions
Do not repair the resemblance. Verify the pathway.
Color and shape can overlap. Timing, location and a repeatable check usually carry more diagnostic weight.
