Finally joined the club! (CTC-9 content)

[zenithfan1]

It does wipe off, rubbing alcohol or strong glass cleaner (I have concentrate from work) does the trick. I think you're right, they seem like they're good for a few more decades, just not sticky anymore. The reason why I cleaned them, besides it bothering me because they were also black is what you said, corrosion, seen it many times when wire is like this. Maybe it's similar to the oiliness associated with the rubber gasket on non-bonded color CRTS, they clean up well and are still supple.