Had a real bad one this week. Looked to me like heat escaping from an old alu window frame had somehow been involved in creating a real bad black mess on the fascia board directly above it. Vir-sol got the loose stuff off but not the ingrained stuff. Had to resort to a cream cleaner on the brush to shift it. Had to switch brushes after and rinse it out when I got home it was so bad. Got a fair price on it though so not out of pocket but would like to have been able to shift it a bit quicker. What do you guys use to clean fascias like these?