Faced with opening that tape box or CD case, what are some of the thing you need to consider before digitisation? There’s preparation to carry out or sometimes there’s conservation issues that might be a stumbling block. Here are some hopefully informative questions to help you assess the situation and decide what actions to take.
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QUESTION 1: You open up an open reel tape box and there is no obvious condition issues. How can you tell what material the tape is made of?
It doesn’t matter what the audio tape is made of.
Apart from wanting to itemise our collections properly there are various conservation techniques that should only be performed on certain material e.g. you must NEVER bake a tape made of acetate as it will damage it.
You can hold the reel up to the light.
Audio made of acetate (and therefore vulnerable to vinegar syndrome – the off-gasing of acetic acid) will appear transparent when back lit. Polyester material will appear opaque and sometime have black backing. This material is more vulnerable to oxide shedding. This tape might not have condition issue yet but now you know which issues to look for.
Cut a piece off and conduct a ‘float test’
No, but this is a quite fallible test used in film preservation for identifying if a FILM BASE is cellulose nitrate (will sink) or acetate (float)
QUESTION 2: You’re inspecting the pack for damage and you see that the tape is not dropping loose (like the image on the left) and is instead sticking to the side of the pack (like the image on the right). What does this mean and what should you do?
The reel has some binder hydrolysis AKA sticky shed syndrome.
Carefully, slowly start to wind through the tape on the player. Is it playing ok? Is it squeaking? Is it leaving any musky residue on the rollers and heads? Are there shards of oxide shedding off the tape? Sticky shed syndrome happens when humidity causes the magnetic tape’s binder to deteriorate leaving a sticky residue, in this case stopping the tape from falling freely down with gravity. You may consider baking this tape overnight (50c for 8hrs) to remove moisture and attempt to digitise the next day.
It’s suffering from rusting
If it’s mouldy it would be best to isolate as playing this would be a health and safety risk. Only attempt to clean/remove a superficial top layer with a mask on and magnetic cloth. Use conservation extraction chamber and play in a room with good ventilation. Do not attempt this with any seriously mould tapes and isolate them for now.
QUESTION 3: You thought that the condition of this audio cassette looked fine to play and even digitise so you have. You can hear a horrible squeaking sound when you played the tape in the machine and also a weird digital squeaking sound when you playback the file you made. What’s wrong with this tape and what should you do?
The tape has some binder hydrolysis AKA sticky shed syndrome.
Yes, this condition can also affect audio cassettes. Any magnetic tape stored in a humid atmosphere can start to chemically breakdown and become sticky. In bad cases you can also attempt to bake audio cassettes too.
The tape must have snapped. You’ll need to make a splice to repair.
No, if it snapped the tape would have stopped. Often squeaky tapes will also come to a stop but a tape break won’t sound squeaky in person or on the digitised file.
The tape is positioned in the shell incorrectly.
Do you know what, this could be the case as it’s easy for a tape in a loose or broken shell to slip or twist. It could be rubbing on the outside of the shell and not on the pressure pad. HOWEVER the squeaking is more likely to be due to something else….
What is the best way to splice an audio tape? Either in fixing a repair
or adding leader?
(NB: leader is blank plastic tape of the same width as the tape. It is added to the start ‘head’ and ‘tail’ of open reel tape. This is so that you have enough length to lace it through the player and play from where the recording actually starts on the tape.)
Diagonal Splice with tape on the backing
Yes. The Diagonal shape is to minimise any audible transition.
Straight splice with tape on the backing
No. This could create an abrupt transition with an audible click or pop sound.
Wrap tape neatly around both sides.
No. This will mean that the tape will cover the oxide side
which with block the signal from being picked up on the playback head.
QUESTION 5: ‘Print through’ is when the audio signal from the closely surrounding tape, imprints part of the signal (within the magnetic particles on the oxide layer) back on to the adjacent tape.
Magnetic tape has a coating of ferric oxide powder, bonded to a plastic base (acetate or polyester) with a binder. It is this oxide layer that contains the magnetised particles that carry the audio signal.
Depending on how the tape is wound this can result with an audible pre or post echo. Winding through the tape a few times can help reduce this. What ways can you address this with storage?
Store the tape, oxide in and tail out.
Yes. This is so that any echo produced will sound more natural
as a post-echo that we are much more used to hearing.
Store the tape oxide in and head out.
This isn’t ideal as any echo produced will sound unnatural as a pre-echo.
Store the tape, oxide out and tail out.
This way will also produce a pre-echo.
Some consider oxide OUT and head OUT to work to minimise print-through
but you would need to regularly be twisting the tape 180 degrees whilst winding
so it less manageable on some players.
Minimising Print-through By Michael Gerzon Click to access Print-through_USL.pdf