Bad Tapes. 1 bit of info...

This is turning into an Urban Legend as we watch - or, as was once quite succinctly put: "The plural of anecdote is 'bullshit'". ;} Some older formulations of tape - notably Ampex Grand Master 456 - has proved unstable over time. Recording tape of all kinds consists of a plastic strip, called the backing, made of various type of plastic - cellulose nitrate, acetates, or polyesters generally - with some formulation of a ferrous powder applied to it. The powder is very finely divided iron oxide, crystalized microscopic metal particles (acicles), or verious magnetic alloys - all reduced to a very fine dust. This dust is mixed with emulsifiers and lubricants, as well as an adhesive (the binder) to keep it stuck to the surface of the backing. There are two main modes of [chemical] tape filure - either the backing fails, as when acetate tape decomposes and the acetic acid coalesces out - giving some old tapes that 'vinegar' smell, or other failures of the backing chemistry to cause it to break, warp, or disintegrate. OR - the binders fail and the oxide layer becomes disassociated from the backing altogether (flaking or peeling), or the binder adhesives begin to 'weep' out of the oxide, and then it gets the whole tape path gooey and everything comes to a viscid halt in short order. In cases where the binders are failing - it is possible to try and dry the media in an oven - very low humidity and about 120 - 150 degress F for a few hours. Then it can hopefully be played back and the program recovered. I've had mixed luck over the last 20 years of direct involvment in audio and media restoration of all types. I've had some impossible-to-play tapes return completely from the dead - and I've had reels that had fused into a sorry, solid block of gooey ruin... These failures are much less common with data cassetes and 1/2" computer tape, because the formulations and speeds, etc, are different. Nonetheless, baking media is sometimes quite effective - but it's best if you know pretty much *why* you're doing it in the first place - and also it's good to have a firm idea of exactly what the next step after baking is going to be - because you won't have much time to try and recover your data after that. Cheers John