2.1.1.1 Cylinders
With cylinders, the groove is cut in a helix across the surface. The modulation of the sound signal is engraved vertically (“hill and dale”).
Figure 1: The recording and reproduction principle of cylinders.
There are instantaneous and replicated cylinders. Cylinder replication was possible either by a copying process from masters, which allowed a limited number of slave cylinders to be made. Another process was replication from a galvanoplastic negative, a copper tube, which carried the “inverted” groove on the surface of its inner side. These negatives were used to make wax casts or to create celluloid (=cellulose nitrate) positive tubes produced under high pressure steam. The celluloid tube was then stabilized by inserting a core made of plaster or other materials.
Figure 2: Replicated cylinders: wax (left), celluloid (centre) and wax “Pathé”.
Figure 3: Self recorded cylinders: wax, affected by mould (left) and “Edison Concert” (right).
The various wax compositions used for wax cylinders are chemically fairly stable, if properly stored. Wax, however, is highly susceptible to fungus growths and, as many cylinders were inadequately stored in their earlier lives, fungal infection (mycosis) is commonly found. Fungi aggressively attack the surface of the cylinders and seem to aim for wax as their primary nutrition source. Additionally, the digestion process is associated with the secretion of acids and enzymes, further damaging the material of the cylinders. Complete removal is not possible. Prevention of further fungus growth is, therefore, of utmost importance. Chemical breakdown can also occur under the same conditions that promote fungus growth. Typically this takes the form of “efflorescence,” which can be mistaken for mould, but appears to involve the actual separation of constituent materials in the metallic soap composition.
Celluloid cylinders suffer from brittleness of their cellulose nitrate surface, but catastrophic deterioration as occurs in nitrate films has not been experienced. Mechanically, all wax cylinders and the plaster cores of celluloid cylinders are extremely fragile.
