Originally Posted by drp audio
Question, will it destroy a tape to bake it if it is not gooey? Graham Hinton suggested damage potential but I'm leaning towards joeq's advice, just bake it and don't ask questions! As I research tape baking on GS and online in general it seems like bake temperatures are consistent but there are great variances in bake time (3-8 hrs), leading me to believe that baking too much is less of a concern, leading me to believe that baking a tape which is already dry may not harm it(?). Does this reasoning make sense?
No. You cannot unbake a tape. If the material on it is important proceed with caution.
I’ll forget about using old tapes for new material. I’m happy just to capture some old tracks into a DAW and make sure the tape machine is working fine at this point. Fortunately the tapes in question are my own material and I run 30-60 seconds of blank tape before using a tape to record. At 15ips this gives me some tape to experiment with before I hit program material. I will try a pre-check by running some tape between my thumb and a screwdriver shaft (shiny, round and cleaned with tape head cleaner). I’m thinking that this will simulate a tape guide or the like …(?)
Sometimes you can play for twenty minutes with no indication that a tape is sticky. Until you try to rewind and the motors stall.
Your proposed test will only show the extremely bad cases.
Here’s my plan unless I get convinced that it is okay to bake a tape without even running it simply to ensure that it is dry before use.
1) Spin reel with hands to see if tape falls freely from reel. Just curious about this. Then I’ll …
2) Slide 3-4 feet of tape end against a clean screwdriver shaft and check for tape “goop” (simulated metal tape guide …?). If there is evidence then baking is needed then I will bake. If not then I will …
3) Load tape and run over tape lifters for about 10 seconds then check for tape goop. If all is clean then I will …
4) Load the tape onto reels and try a pass over the heads with monitoring all set, and I’ll be watching and listening VERY close for problems and I’ll be ready to shut it down immediately if needed. Stop and check heads after a few minutes of playback.
If I need to bake I will bake for 6-8 hours at 130 F degrees.
Too short a sample, too long a time and a bit too high a temperature. You only want to remove the moisture that has incorrectly been absorbed into the binder, not the moisture that was there before that.
I would try to play the tape to assess its condition and then, if necessary, bake for 2 hours at 120 F. Then reassess and judge how much further it needs by the change. It's something you have to get a feel for and you'll only get that through trial and error. You just don't want to make the errors on anything really important. So it depends on the consequences of losing what is recorded on the tape, once it's gone it's lost for good. Too much caution and you have to clean the tape path again.
The state of sticky tapes can vary greatly, it depends on how much moisture has been absorbed over the past 25+ years and the storage conditions. I find that once a tape has gone sticky that the black goo is coming mainly from the matt backing which is black and will build up on rollers that touch that side of the tape. After baking, there tends to be more oxide shed on the heads, which is brown deposits. I have had a few cases where the oxide has shed in serious amounts on the first playing after baking, it is quite a disturbing feeling watching pyramids of rust grow knowing that it contains the recording.
You are dealing with a thin strip of plastic that has dust stuck to it on both sides with a polyurethane "binder" and it is the latter that has become runny. It depends how much it has crept over time. Overbaking may bake together the backing from one side with the oxide on the next turn and then one side will be torn off the tape as it unspools.