have a room with large 60-yr old window w/wood trim . have another
window (15 yrs) in same room w/white non-wood trim. began using a
humidifier in room - hygrometer says 45% rel hum.

this week while cleaning, saw little spots of blackish mold growing
along the bottom edge of the white non-wood trim window. assuming
it's due to the condensation that falls from the window. not a whole
lot - got some vinegar, sprayed, wiped clean, no problem.

took a look at the other window (old wooden one) and where the glass
meets the wood, there's a large streak of this black stuff on the
wood. took a paper towel with some vinegar (i know i probably
shouldn't), wiped it along the wood and ALOT of black stuff came onto
the towel. odd thing is the stuff doesn't look like the typical
circular mold colonies.

what is it? typical of mold? mildew? or does wood rot like that? or
could the locks/handles be causing problems? even after wiping it a
million times, wood still looks black - like someone ran their finger
in black shoe polish and rubbed it into the wood.

getting windows replaced this summer, but sinuses need the humidifier
now (dry cold winter).