Exercising magnetic tapes

Michele Zeccardi asked about playing/rewinding magnetic tapes.  I began
producing training videotapes approximately 12 years ago.  My practice
when making copies is to leave the tape at the end of the production.
When another copy is requested I forward the tape to the end and let it
rewind.

With or without use, each tape is cycled once a year.  Reproduction
masters are maintained at no more than 70 degrees F, at an RH which
varies from 40-50 %RH over the course of the year.  To date, I have had
no problem.  However, I do keep the equipment clean.  Heads can pick up
dust and create scratches in audio/video tape.

As to motion picture film, if it is left tail out (i.e. has to be
rewound to play) and is stored in film cans there should be no problem
if the film is not run for a few years, provided the storage conditions
are stable (even if they are not "ideal").  There are problems with
nitrate and some acetate film stocks, especially in poor storage
conditions, but an amazing amount of film has survived.

If you can't get to everything all at once, do everything possible to
maintain a stable storage environment and cross your fingers.

One important thing to bear in mind as the preservation plan you speak
of is being written is that human readable records are likely to survive
longer than those which require interpretation by intermediate
machinery; i.e., film will be "readable" when the machinery which
"reads" audio/video tape is out-of-stock; un-repairable.

Jack C. Thompson
Thompson Conservation Lab.
(Istor Productions)
Portland, OR

                                  ***
                  Conservation DistList Instance 8:17
                Distributed: Thursday, September 1, 1994
                        Message Id: cdl-8-17-003
                                  ***