Cleaning audiograph disks

There are several thousand audiograph dictation disks of recordings
of the Utah Legislature and Supreme Court.  I'm interested in
identifying the materials they're made of so we can clean them
before duplication them and make sure we house them properly.

The audiographs were recorded between 1952 and 1989(!).  The disks
and the audiograph players were manufactured by Gray Audiograph
Dictation Systems, Gray Manufacturing, Inc.  Each disk is 8 inches
inches in diameter with two 1 1/8 inch slots.  They're blue plastic
and a little softer or floppier than the phonograph disks I've seen.
They remind me of the records they used to have on kids' cereal
boxes sometimes.

St. Laurent recommends cleaning grooved disks with a combination of
types of Tergitol and distilled water.  I'm concerned that Tergitol
will be difficult to obtain and work with.  My guess is that the
audiographs are vinyl, so we could clean them with isopropyl alcohol
and distilled water.  That seems easier.  However, I'd like to be
sure since I know alcohol is bad for shellac.

I appreciate any information you can share with me about identifying
and cleaning these materials.

Sarah Talley
Preservation Archivist
Utah State Archives & Records Service
P.O. Box 141021
Salt Lake City, Utah  84114-1021
801-538-3186
Fax:  801-538-3354


                                  ***
                  Conservation DistList Instance 14:3
                  Distributed: Thursday, July 6, 2000
                        Message Id: cdl-14-3-010
                                  ***