There would be little point in telling the story of Instrumentation Tape Recorders without also including the tapes that they used. Instrumentation Magnetic Tape is different from Audio tapes in that it is better quality, is formulated for different signal wavelengths and is designed to last a long time while minimising magnetic head wear.

In the 1950’s and 1960’s tape production was dominated by the 3M company and it’s Scotch brand, and the Ampex tape company. Later on, Sony produced high quality magnetic tape along with other entrants like Maxell.

To illustrate the requirements for Instrumentation Magnetic Tape, here is a series of product information brochures, c. 1967, and some technical notes on how tapes were made. Note that it was common to have many different formulations of tape, depending on the intended end use. Note too the concerns expressed about the effects of Nuclear Radiation on tape integrity, at a time of Cold War tensions!

3M 403 Tape Brochure
3M 481 Tape Brochure
3M 486 Tape Brochure
3M 591 Tape Brochure
3M 991 Tape Brochure

And for comparison a domestic Audio tape of the period
EMITape Brochure