78 rpm records

Elizabeth Dunford <elizabeth.rl.dunford [at] googlemail__com> writes

>I work at a historic house where there is a small but significant
>collection of 78 records belonging to the original owner of the
>house. They all date from before 1950 and are stored in albums. Some
>of these albums represent collections put together by the owner,
>whilst others are as bought, e.g. Mozart Symphonies. They are mainly
>Columbia and HMV records, purchased, we think, during the 1930
>although some date back to the mid 1920s.

There are very useful articles both in the Plastiquarian (summer
2000) and in Antique Photograph News (September-October 1993), on
the manufacture of 78s.  You are most likely dealing with shellac
discs, and possibly some vinyl.  Shellac disks tend to be thicker,
and are often a dark brown colour.  These were made of shellac,
copal resin and a mineral filler (many variations in recipe were
used depending on manufacturer).  They are very susceptible to
fungi, and also to dimensional change in high humidity. The results
of aging include embrittlement, warping, loss of extender and
condensation of shellac.  These were replaced by vinyl records
towards the end of World War II, originally in the smaller 45
format. Vinyl records in America, went on general sale in 1948;  and
larger LP records in 1950. They are characterized by being thin and
a variety of colours.  They are generally resistant to mould or
fungi growth.

Sue Warren
Manager, Conservation
Canada Science and Technology Museum Corporation
1867 St. Laurent Blvd.
PO Box 9724
Ottawa Terminal
Ottawa, Ontario K1G 5A3


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                  Conservation DistList Instance 24:48
                  Distributed: Tuesday, April 19, 2011
                       Message Id: cdl-24-48-006
                                  ***