Not Soap Suds

This is dryer lint so fine it was dusty; almost powdery. Wonder what the venting hose looks like now - and we cleaned everything out not that long ago. I made the mistake of laundering old, old curtains and the cotton-lining disintegrated; what a mess. I wouldn't ordinarily dry them in the dryer, but wanted to get them back on the windows upstairs where we're putting up new storm windows.