[QuadList] Plasticizer--Photos?

[Dale Lamm]

After seeing a photo, must say I've seen this same effect on quarter inch 
audio tape that has been in storage for years. I too thought it was mold, 
but the cardboard boxes containing the reels were dry and spotless. The tape 
was not sticky, but the white, powdery gunk would quickly land on tape 
guides and the head stack.

My low-tech solution was to spool the reels in fast forward, holding a clean 
cloth against both sides of the tape to collect the material. It came off 
easily and looked fibrous, like finely ground cotton. I assumed it was some 
chemical breakdown of the cellulose acetate base, but from reading here, it 
could have been deteriorated lubricant.