When we catalog our tapes, we’re sure to record the type of case they’re housed in. There are two or three common types, but the most distinct is one we’ve taken to calling the “latching clamshell” in our records. They look like this:
Recently our colleague Alan told us that he knew these cases as “mailers”, as they were used to send tapes through the mail, without additional packaging. Since many of our tapes are music videos or promotional materials, it makes sense that they’d have traveled through the mail. These cases are also remarkably solid—the latch keeps them firmly shut, and the plastic is thick and robust. They close so tightly I wonder if they’re not waterproof.
The other day I was cataloging the above tape and noticed the patent numbers on the case. On a whim I looked up the numbers and found the following 3M patents, all from 1978-79:
- 4,177,896, ”recessed hook and handle for a plastic box”
- 4,153,178, “Double-acting latch for hinged plastic box”
- 4,211,337, “Multiple-point hinge for double-wall plastic box.”
There are diagrams, of course:
Call me crazy, but after handling so many of these cases, it’s neat to learn about their development. Here’s part of the description from one of the patents:
The novel latch inherently presents a clean, uncluttered appearance and is readily engineered at low cost to have a useful life equal to that of the box. Laboratory tests of a blow-molded plastic box of double-wall construction equipped with the novel latch indicate that the latch should be able to withstand rough treatment such as that sometimes encountered in the mails while remaining virtually immune to accidental opening.
Immune to accidental opening! I believe it. I had no idea that the cases were double walled, either, but I can now see how this would help protect tapes being handled roughly as they go through the “mails.”