Paper or Plastic
The first tapes were paper-based. Paper tape varied from light to medium brown in colour, and you can see light glow through it. Tape from this era is now brittle and breaks easily. Over time, this isn’t a great way to archive historic recordings.
In the 1960s tape was made with plastic or polyester. This tape base is far more durable than paper tape, and ranges from light to dark brown depending on the age and manufacturer. Generally speaking, the darker the tape, the newer it is, although there are exceptions. The quality of older plastic tape is the equivalent of a ‘normal bias’ cassette tape and good for both speech and music use. The tape tends to be relatively stable, and even 50 year old tape can still be good to use today.
This older tape can reach saturation, or the point at which it distorts around +3db, so you don’t want to peak the level meters on your reel-to-reel when recording as you’ll hear this distortion.
Popular brands: Ampex, 3M, Sony, Irish, TDK, Maxell, BASF.
Back-coated Tape
Sometime in the mid 1970s, engineers developed back coated tape, which quickly became the industry standard and preferred tape in both recording studios and at home. Back coated tape still has a brown oxide side, which faces the tape heads, but the back side of the tape is a charcoal gray or almost black color. This back coated tape allowed recordings to be made at a much higher level than normal tape, which improved the signal to noise ratio, the frequency response was better, and recordings resulted in less distortion. Referring again to cassettes, back coated tape was the equivalent of chrome tapes. Back coated tapes were priced at a premium due to the better performance. Back coated tapes could be recorded typically at +6db to +9db.
Popular brands: Sony, Ampex, 3M, BASF, Quantegy, RMGi, ATR.