Magnetic tape can be used to record anything from an audio track to computer data, so choosing the right one can depend on what you need it for. There are a few different materials that these tapes can be constructed of, each of which offers different recording characteristics and life expectancies. If you need your data to last for a long time, evaporated metal magnetic tape typically lasts the longest. You may also want to look at the material a tape is made out of if you are concerned about audio or video fidelity, in addition to checking for a high signal to noise ratio. Other factors, such backing material thickness, can be important if you want tape that will stand up to repeated use.
One of the most important factors to consider when choosing a type of magnetic tape is the material it is constructed from. Some of the common materials that are used to create magnetic tapes are ferric oxides, chromium dioxide and evaporated metals. Both ferric oxides and chromium dioxide also include a binder that holds the metal particles on the tape surface, while the evaporated metal technique requires no binding agents. Ferric oxide tapes last about three to five years, while tapes that use chromium dioxide or evaporated metals typically will not degrade for about ten years. It is usually possible to read evaporated metal tapes more often than those that use chromium dioxide without damaging the recording.
The material a magnetic tape is made from can also affect your tape player or recorder. Lower quality tapes tend to leave more oxide deposits on the tape heads during use, which can make it necessary to clean and demagnetize your hardware more often. If you plan to use your tapes regularly, you may want to choose an evaporated metal tape that does not use a binding agent.
One factor to consider if you want high quality recordings is signal to noise ratio. This refers to the amount of noise that you can expect in your recording from imperfections or other issues with the tape itself. Since there is no one standard that all manufacturers measure this ratio against, it can be difficult to directly compare one brand against another. You may need to experiment on your own, or rely on the experience of others, to find tapes with the best ratio of signal to noise
You may also want to consider the physical construction of a magnetic tape if you plan on using it repeatedly. Some tapes use thicker backing materials or substances that are specifically designed to stand up to repeated use. The tape in high density cassettes is typically thinner, but in some cases manufacturers will compensate for this by using tougher materials.