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Deterioration of modern media

The following audio visual formats can be found in the HIV/AIDS collection:

  • VHS and Audio cassettes
  • Film reels

Media such as this can deteriorate due to chemical and physical factors, and is also at risk of becoming obsolete as technology advances.


VHS and Audio Cassettes

There are 32 VHS cassettes and 26 audio cassettes in the HIV/AIDS collection. These formats are known as magnetic media as the tape used to carry the information is made from a thin layer which is capable of recording a magnetic signal supported by a thicker film backing.


Magnetic media can be damaged through viewing in the following ways:


Physical Factors


  • Mechanical Damage – Playback of the media on poorly maintained viewing equipment can cause stretching or creasing of the tape. Damage to the edge of the tape can be caused by inappropriate winding in the viewing equipment.  The tape will not play if the edge is damaged as the tape’s control track (a signal that tells the viewing equipment to pull the tape through the machine) is located here.
  • Unsuitable Storage – This can result in debris becoming embedded on the tape which can interfere with the magnetic signal
  • Inappropriate handling – Oils and chemicals compounds can be transferred to the tape through careless handling
  • Magnetic Fields - The tape can become demagnetised by contact with strong magnetic forces such as electrical fixtures, loudspeakers, vacuum cleaners, floor buffers. This changes the magnetic signal and it will become unreadable.


Chemical Factors

  • Binder degradation -  The binder used to hold the metallic particles on the tape substrate may degrade in the presence of moisture through hydrolysis. In this process, the bonds within the binder break resulting in loss of strength. This can lead to the occurrence of “sticky shed syndrome” resulting in a soft binder with a tacky surface. This residue can collect in the viewing equipment and cause it to stop running.
  • Loss of Lubricant – Lubricant is added to the tape to reduce friction whilst playing. This facilitates the movement of the tape through the viewing equipment and reduces wear. The level of lubricant decreases over time. It can be lost during playing and it can also evaporate whilst in storage. Without this, the tape cannot be viewed. 

Film Reels

In the HIV/AIDS collections there are seven film reels dating from the late 1980s to early 1990s. At this time, a polyester-based film would have been used.


Film reels can be damaged in ways similar to VHS and audio cassettes:


Physical Factors


  • Mechanical Damage – Sprocket and edge damage can be caused during playback on poorly maintained equipment
  • Unsuitable Storage – If the film is unprotected, there is a risk that debris and dust can become embedded on film and interfere with the playback of the material. Equally, if the film is stored in it’s original metal can, there is a risk rust could leave iron oxide deposits on the film.
  • Inappropriate handling – Oils and chemicals compounds can be transferred to the tape through careless handling


Chemical Factors

  • Polyester based film, such as that found in the HIV/AIDS collection, is not subject to the same deterioration processes found in acetate and nitrate based films. Its natural deterioration process has not yet been identified.