The Shell That Protects the Tape

(The second entry in a six-part series on audio preservation.)

A confession:  In approaching this topic, I thought we’d be saving the cassette shell!  But to a preservation professional, the cassette shell – with its plastic and pins – is a distant secondary concern:  the real focus is always on the tape itself.  Ultimately, you don’t even have to preserve the shell.  It’s just a box that holds the real treats inside.

Cassandra Gallegos, Preservation Administrator for George Blood Audio and Video, makes the process of protecting the precious magnetic tape sound relatively easy:



The pressure pad on this cassette
has deteriorated necessitating
changing the cassette shell.

“The most common cassette problems – such as missing or deteriorated pressure pads, rusty pins, or pest infestation – can be fixed by simply changing the cassette shell.  However, the solution here brings up an additional problem.  Finding empty cassette shells can become a lesson in futility.  We buy as many as possible when we find them.  Another option would be to use the cassette shell from a cassette that you do not wish to keep, making sure to carefully indicate the oral history on the new cassette shell.

“There are two types of cassette shells: sonic welded and 5 screw.

“The halves of a sonic welded cassette shell are sonically vibrated until the plastic fuses together.  If you find yourself in possession of one of these cassettes, carefully score along the welded edge with a sharp blade.

“The 5 screw is screwed together with 4 screws in each corner and one screw in the center (an eye glass screw driver should do the trick).  Make sure the new shell is a 5 screw so you’ll be able to close it up once you’re finished transferring the tape to it.  Always keep the cassette on a flat surface to keep the tape from falling out of the shell as you work with it.  Take note of how the tape is wrapped around the various plastic posts inside its shell.  Transfer the two plastic hubs (the tape will be attached to both) to the new cassette shell (and remember to use gloves!).  You want the cassette to sit in the new shell the same as it did in the old shell with all the same pieces present.  If you are missing some pieces in the new shell, which can be the case if you purchase an empty cassette shell, transfer these pieces over as well.  You’ll probably notice

two rectangular pieces of plastic

Open cassette and
slip sheets.

inside the shell. These are slip sheets.  They keep the tape running smoothly.  Now screw the two new shell halves together again.  Place a pencil or your finger in one of the center gears to make sure your tape moves as it should.  If it doesn’t move, you probably didn’t wind the tape around the plastic posts correctly.  The ease at which you perform this activity depends on manual dexterity and your tolerance level for frustration!

“A good primer on the handling and storage of magnetic tape is Magnetic Tape Storage and Handling by Dr. John W. C. Van Bogart, available as publication #54 through the Council on Library and Information Resources (CLIR).”

© 2010 Lee Price