Preservation Issues

To date, the Library of Congress has preserved hundreds of thousands of sound recordings in most historic audio formats. The Library's sound engineers have transferred cracked 78's, delaminating instantaneous lacquer discs, snarled and broken wire recordings, moldy cylinders, and deteriorating open-reel tapes to more durable formats. In recent years, the Library has focused on using high-quality, digital files as the preferred preservation format, while retaining all original recordings in the hope that future technology may be able to free the sound from them. Such digital preservation, which is increasingly being embraced by audio archives, promises to allow the easy migration of files to future systems.

Other preservation efforts of the Library include working with the National Recording Preservation Board to commiss standards and reports on audio preservation through the Council on Library and Information Services (CLIR). Currently, the Library is also collaborating with the Lawrence Berkeley National Lab on an exciting new imaging technology that will allow discs to be played back without any part of the player touching its surface.

Preservation Issues with Cylinders

There have been several formulations of the audio cylinder. The earliest "cylinder" recording capable of playback was the foil that Thomas Edison wrapped around a drum. Early Bell Tainter cylinders had a cardboard core with a wax coating. HUMIDITY. Such recordings are sucsceptible to delamination and are sensitve to changes in temperature. A corrosive mold preys on later formulations of wax cylnders and it can completely dissolve the grooves. Proper temperature and humidity must be maintained to insure against such damage. Some wax recordings also become extremely fragile with age and the slightest touch can cause them to crumble.

 

MOLD TWO PROBLEMS

1) Fungal Metallic soap compounds (brown wax) susceptible to biological attack. Fungus feeds on organic compounds in the metallic soap. Causes irreparable physical damage.

2) Efflorescence -- exudation of usually oils and waxes to surface. They cause discoloration add surgace noise. NOt truly mold. Often confused with mold.

 

Celluloid Cylinders (Blue Amberol, Indescrutible, Lambert)

Celluloid sleeve supported on a core.

Celluloid shrinks over time due to loss of camphor, which was originally used to make celluloid moldable.

Builds up stresses because core constrains shrinkage. Tension causes cracking and splitting.

 

 

Preservation Issues with Instantaneous Lacquer discs

There are a number of preservation problems that beset lacquer discs. Probably the most common is the exudation of palmitic acid that serves as a plasticizer, keeping the lacquer pliant. The early sign of deterioration is the appearance of a powdery, white residue on the discs surface. Once the plastcizer is gone the lacquer surface becomes brittle and cracks. In the example shown to the left nearly the entire playing surface of this glass disc has vanished. Engineers at the Library of Congress labor to transfer such recordings to a new, more stable format before such extreme damage occurs.

Another major concern with lacquer discs is that during World War II because aluminium was a war material,

 

 

Preservation issues with 78-rpm disc formats