Cleaning dusty servers is one thing - but I have a slightly different problem: Soot in the servers!

During some warm summer months, we needed to open the windows at our server room.
Unfortunately, the windows are located directly above the exhaust vent from a diesel heater, and we soon discovered that all our servers were (internally and externally) covered with a fine layer of soot. The soot sorts of "stick" to the surfaces, making cleaning a difficult task to say the least.

I wonder if anyone has any experiences in removing soot when vacuuming / compressed air doesn't work. Some surfaces can easily be cleaned with paper towels / water, but not the circuit boards, fans and power supplies.

I would guess this could also be appliccable to servers salvaged from fires etc.