What Materals In 78 Rpm Records

Amon Skres

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26-01-2025

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78 RPM records, a mainstay of the recording industry from the late 1800s to the mid-1950s, were crafted from a specific blend of materials designed to withstand the limitations of early recording technology. Understanding their composition helps appreciate their historical significance and inherent fragility.

The Core Material: Shellac

The primary component of a 78 RPM record was shellac, a natural resin secreted by the lac insect. This resin was processed and mixed with other materials to create a workable compound. Shellac provided the record's structural integrity and contributed to its characteristic warmth of sound, though it also contributed to its brittleness.

Fillers and Reinforcements: Improving Durability and Sound

To enhance the shellac's properties and reduce manufacturing costs, various fillers and reinforcements were incorporated into the mixture. These typically included:

• Filler materials: These materials added bulk to the shellac and helped reduce the cost of production. Common fillers included various types of mineral powders, like clay or calcium carbonate. The exact composition varied between manufacturers and sometimes even within the production runs of a single manufacturer.
• Pigments: While not structurally essential, pigments added color to the records. Common colors were dark brown, black, and various shades of reddish-brown. The color often depended on the filler materials used.

The Process: From Mixture to Masterpiece

The carefully measured mixture of shellac, fillers, and pigments was then heated and molded into the familiar disc shape. A master recording was used to create a negative mold, and the shellac mixture was pressed into this mold, resulting in the finished record. The process required careful temperature control to ensure the shellac flowed correctly and solidified properly.

The Fragility of 78s: A Legacy of Materials

The materials used in 78 RPM records—while sufficient for their time—contributed to their inherent fragility. Shellac is prone to warping, cracking, and chipping, especially with age and changes in temperature and humidity. The fillers, while strengthening the shellac, didn't eliminate its brittleness. Therefore, the proper handling and storage of 78 RPM records are crucial for preserving this important piece of audio history.