Saving Tape

Since the 1970s people have recorded events on videotape. But can you still watch them? This series of articles, written by video conservator Jamie Lean, explore the issues surrounding the preservation of videotape.

Part 2 - What is Videotape?

We use videos constantly but do we know what they are made of?

Videotape was originally created to allow the major TV networks in the USA to broadcast their evening news at 6pm in every time zone in the country. Ampex and RCA developed the 2” video format so that the news could be broadcast on the East Coast at 6pm then transmitted across the country to be recorded on videotape and replayed 2 to 4 hours later in the various regional time zones ending on the West Coast.

The construction of magnetic videotape varies according to type and manufacturer but the basic videotape consists of 4 layers—a flexible polyester base; a layer of magnetic particles held to the base by a layer of polyurethane binder (or glue); and a lubricating top layer that helps to seal the magnetic layer in and assist the tape to run smoothly through the video machine. These layers usually total no more than half a millimetre thick and are tightly wound into cassettes or onto reels.

Each of these components can cause problems but the most frequent arise from the binder. The binder is often a secret chemical formula closely guarded by the manufacturer and is prone to breakdown under stress (heat and humidity) or age. It can then leak out, jamming machinery and freeing the magnetic particles to clog up video heads. If the magnetic layer is exposed to the air it can start rusting and this is most frequently seen along the edges of tapes. If the lubricant layer dries out or is worn through, tapes may stick on the video heads and rollers.

Videotape is manufactured in large sheets, fed over rollers, sprayed and baked in industrial processes. The basic tape is then sliced to the correct widths (1/2” VHS, 8mm etc). Higher quality tape comes from the same rolls as the lesser quality tape but from the middle of the rolls rather than the edges or ends, where there may be some slight stretching or other easing of manufacturing tolerances.

Tape Tips #2
If you have a favourite video that is starting to show signs of deterioration, such as speckle or tracking lines, the best thing to do is dub it to a new tape. You will lose some quality but the deterioration should be halted for the time being.

Saving Tape - Part 3 Why Save Videotape?