[slvinstall]

It looks to me like the previous owners of this house removed insulation from the ducts, but stopped when they got to the portion of the ducts going into the wall. I am guessing it was asbestos. There is a dull white residue left on the ducts. I am wondering if this is most likely just adhesive or paper left from the insulation or if it likely contains part of the asbestos insulation as well. I will try to post a pic.

 

[beenthere]

Can't tell, the pic is too much of a close up.

Often they put a mastic sealer over the duct after removing asbestos from it.