Black Stuff Inside Thermal Pane Windows

Saw something today new to me. House was about 3-5 years old. Vinyl Thermal Pane Windows (double hung, casement and fixed). 2-story at front and 3-story at back and rear end/sides of house.

Fiberous / Hardboard 4x8 siding panels. Wood trim with flashing over trim and over windows. 35% of all windows had weep holes still closed up.

Of that 35% about 1/3 had moisture deterioration to wood trim below the window. Several windows had been heavily caulked (silicone). Seller said they’d been there 3.5 years and had 1 leak during HEAVY wind-driven rain - NEVER again.

Tramex Moisture Meter showed high under 3 windows / Mediocre or 0 at others. On about 35% of T-Pane windows when you looked down at the silver metal T-Pane Track between the glass you saw bits of black something (almost like you had crumbled black crackers OR spilled black ashes in there). This is a NEW one to me (mold, mildew, OR ???).

Thoughts …

Could it be that the seal is breaking up and falling apart ? I have seen that once myself . Look at the seal at top bottom and sides of the seal .

I’ve seen in some older wood double pane windows and a few vinyl windows. I chalked it up to algae growth between the panes. My guess is either contamination from the factory combined with failed thermal seal… or simply failed thermal seal and larger breach not identified through normal inspection allowing contaminates to enter between the panes.