What were 78s made of? - Part 1

  • An interesting discussion started up the other week on 78-L regarding what 78s were made from. Although as a general rule, most were made from shellac, it is also true to say that some were made of different materials. The discussion on 78-L brought up some interesting finds which I summated below:

    As one member of the list pointed out, a Wiki article suggested bakelite was used in the manufacture of 78s. The wiki suggested:

    "Until the advent of vinyl around the 1940s, most gramophone records were pressed from shellac compounds (although some were made from bakelite)" "Recording cylinders produced by the Edison Electric Company (now General Electric) and 78-rpm phonograph records were originally made of Bakelite. "

    A knowledgeable member of the list refuted some the wiki claims by stating:

    Edison's chemists produced a substance nearly identical to Bakelite (which was developed by Leo Bakeland just a few miles away and practically at the same time) that Edison named 'Condensite'. Both are phenolic resins derived from coal tar using phenolic acid ('phenol') as a solvent. The surfaces of Edison's 'Diamond Disc' records were made from this substance and comprised the playing surface. The Condensite was laminated to the record core, the core being composed of a mixture of wood flour (finely ground sawdust), hide glue as a binder, and later, clay, to resist moisture absorbtion. For a time, a thin layer of rubber was between the core and the surface, but this proved prone to delaminating and use was discontinued. During WWI, Edison's supply of phenol feom Germany's Bayer Pharaceutical was cut off due to Britain's naval blockade, so Edison began manufacturing his own. Within a short time, his company was supplying phenol to all the allied countries. However, his phenol was not as refined as Bayer's, consequently Diamond Discs produced during the WWI period have noisier surfaces than earlier and later examples. The wiki articles are also incorrect in saying that the records were produced by "the Edison Electric Co". Not true! They were produced by Thomas A. Edison, Inc. and many were marked "A Product Of The Edison Laboratories" on the label. Someone needs to edit the wiki articles!

    Another member of the list added more on the Edison manufacturing processes:

    Polyvinyl chloride was developed in the 1930s, and was used for pressing transcriptions almost immediately. It wasn't used for commercially released records until the late 1940s. Very early cylinders were a kind of wax compound, but by the 1890s a harder compound Edison came to describe as a 'metallic soap' was used. The Lambert company was one of the first to use celluloid to mould his cylinders from (these cylinders had a cardboard core), and Edison began using celluloid for his Blue Amberol cylinders (using a plaster of Paris core).

    As Beil points out on the 78-L list, Berliner had a slightly different record manufacturing process:

    I do want to add that Berliner used celluloid for his discs in the early 1890s before shellac -- possibly by 1889 but definitely in 1892 thru 94. There should be some additional research done on whether Berliner really used hard rubber at all. I tend to think that some might have mistaken the celluloid pressings for hard rubber because hard rubber is mentioned in passing in a Berliner letter (I think). I seem to think that he might have experimented in having pressings made but found them lacking. I believe also that the Dethlefson and Frow books detail that the earliest Diamond Discs are also surfaced with celluloid, which they called the transfer sheet process. I had not heard the explanation that this was really rubber coated with condensite. Can we have a reference? Also, in addition to the coreless Lambert celluloids, the cardboard cored Indistructibles and the plaster cored Edison Blue Amberols, there also were the U.S. Everlasting cylinders which had some sort of hard tar core.

    Another source from the list found a website which stated something different in relation to Berliner record manufacture...


    "These records are not made of shellac like records made later, but of gutta-percha: an inelastic compressed and vulcanized natural latex or rubber isolated from the sap of several species of tropical tree, but mainly from Palaquium gutta. They are pressed from metallic matrixes" BTW, please notice that perfect sound on this sample: http://www.archeophone.org/Berliner5inch/berliner-532.php I really don't know what Berliner used to record his own voice, but this sounds almost like electrically recorded to me. I'll follow this interesting discussion up with a further post soon.