Association of Research Libraries (ARL®)

http://www.arl.org/preserv/sound_savings_proceedings/Risk_reduction-2.shtml

Sound Savings: Preserving Audio Collections

Risk Reduction through Preventative Care, Handling, and Storage

Alan F. Lewis
Subject Area Expert—Audiovisual Preservation
Special Media Archives Services Division
National Archives and Records Administration

When I think about risk to a collection of machine-based AV archival materials, I think about:

Hence, our risk reduction thinking needs to have a wider scope than just the stuff on the shelf in the back room. As I view risk reduction, then, I try to think about the recording media as parts of an AV recording system, because without the system, the item on the shelf is of little use. Reducing risk, then, means reducing the risk to all the components of the system.

My assigned topic is to discuss care, handling, and storage:

So to understand these things, permit me to do some basic training first and then briefly review my “19 Conservation Concerns.”

Machine-based audiovisual recording systems are composed of three elements. The first and most obvious, because it’s the “stuff” on the shelf, is the recording media. It is the physical item that has been used to fix in some [hopefully] permanent way the sounds that are the collection, whether those sounds are music, spoken words, or natural sounds. For audio recordings, the media have had a variety of shapes: cylinders, flat discs of various thicknesses, endless belts, wires on spools, and ribbons of material running from reel-to-reel in the open or enclosed in housings.

The second element of a recording system is the equipment, the devices that initially captured and later can retrieve the sounds that have been fixed on the recording medium. Over the century plus that sound recordings have been in existence, the equipment has used transponders to convert sound waves into either mechanical energy or electrical energy. That energy, in turn, drove styli connected to diaphragms or electromagnets. Edison’s original acoustical cylinder machines, for example, used a horn-diaphragm-stylus-soft cylinder as the technology.

The third element is the standards that were developed as a part of the invention of the system. They specify all the details of how the signal passes through the technology, onto the recording medium and later, how they are retrieved in usable form. Again, using the example of a cylinder machine, the standards involved the dimensions of the cylinder, its speed of rotation, the relative softness of the surface to be incised, the number of grooves per inch that the device would cut across the surface of the cylinder, etc., etc.

Now, because I think it is very important to understand the recording media, let me get into a bit more detail. A typical audio recording medium is likely to have at least two of the following components:

It is important to understand that each of these components may have natural enemies which would include their own built-in seeds of deterioration, sometimes called inherent vice in the archives field, as well as unnatural enemies, the conditions we subject the media to over time: its use, overuse, and misuse.

The first component is the base or substrate. It is the physical foundation of the recording medium. It typically has physical size (dimensions) and a shape. It is a cylinder, a disc, a wire, or a tape and generally the term we use to describe the medium is the physical form of that substrate. (“How many discs do you have in your collection?”)

The second component is the information capturer, the technical system by which the information is transformed from sound energy in the air into whatever means is used by the system to fix it on the medium: variable grooves for cylinders and disc recordings and electromagnetic impulses for the magnetic media.

The third component, lacking in some recording media, is a linker, the physical or chemical means by which the information capturer is secured to the substrate. In original phonograph records, one-off instantaneous discs, the linker is the bond between the cellulose lacquer layer into which the grooves are cut and the base material which might be cardboard, aluminum, glass, etc. With legacy magnetic tape materials, the linker is typically a urethane plastic binder. (Modern mass-produced phonograph records have no linker because the grooves are impressed right into the substrate. Likewise, magnetic wire has no linker because the wire itself, the substrate, becomes magnetized.)

Bear in mind that because sound recordings come in so many types, I can’t go into any real detail about any of them in the short period of time I have. However, they include:

a. acoustically made mechanical recordings
b. electrically made mechanical recordings
c. magnetic wire recordings
d. magnetic recordings on paper, cellulose, and polyester base tape

With all of these, knowledge may get more difficult because there are original, one-off recordings and also mass-manufactured products. The bottom line is that if humans created these technologies, the standards and the recordings, something can and will go wrong with them over time. What can go wrong are what I call the “Attacks Against Recording Systems.”

First, with the recording media, there is their own inherent vice, the deterioration factors that are basically manufactured into the media because they weren’t manufactured for the long term. One might think of it as natural deterioration or natural aging because most media were designed for short-term, commercial use with little or no thought for their long-term keeping qualities. Secondly, because these media are handled by people and by machines, there is the wear and tear of overuse and mishandling by the uninitiated, the careless, or the mean-spirited.

Attacks against the technology begin with the real life fact of commercial obsolescence of technologies. Technologies give way as newer systems come on the market that are more desirable and therefore more acceptable. (Consider, for example, how computer removable storage technology has gone from 8” floppy discs to 5-1/4 inch floppies to 3-1/2” floppies to CDs.) Consider, too, that these technologies we use were more often designed for production and/or distribution purposes without thought to their long-term availability. Finally, there are the costs and ultimately the impracticality of equipment upkeep as technicians and spare parts become unavailable and as skilled operators retire or die.

Standards (and software if we’re in a digital domain) are also subject to obsolescence as new versions are developed and the old ones are consigned to the audiovisual scrap heap. In cases where new versions are marketed, the question of backward compatibility arises as version replaces version. Consider with grooved discs alone, how standards have changed with cutting inside-out to outside-in tracks, rotation speeds from 16-2/3 rpm and 78 rpm to 45 and 33-1/3 rpm (to say nothing of half-speed mastering!), and groove pitch from old standard (100 grooves/inch) to microgroove’s (200 grooves/inch).

Finally, there is the legitimate concern about quality loss through signal compression that discards information (lossey compression) and even what can happen with compression that doesn’t dispose of material (lossless compression) but may leave audible artifacts as a result of the electronic processes.

In summary, in my view, risk reductions starts by knowing the details about the media, the technology, the standards, and the software, and paying attention to those details.

Now, let me move on to my “19 Conservation Concerns” because whether handling the media or storing it, these are relevant. Again, because of the complexity of the audio recording field, much of this needs to be general and not medium- or system-specific.

+Environment. Conservators in all fields, not just AV media, cite the temperature and humidity conditions in which heritage media are stored as the single most critical factor in their long-term survivability. If materials held by an archive are not to be at-risk, proper levels of temperature and humidity are required. Because of the diversity of sound recordings to be discussed in this conference, I cannot make any single recommendation but rather suggest that each archive consider the variety of media it holds, do the research on a medium-by-medium basis, and design storage environments that are appropriate for each. I will say that at present, the U.S. National Archives holds its wire, acetate, and polyester magnetic media and its mechanical media at 65 deg. F @ 30% RH. The environmental control system must operate “24/7/365” and must be monitored and recorded continuously in order to have proof-of-performance of the system.

The traditional “no smoking/eating/drinking” rules always apply. Unpacking collections should take place away from storage and use areas so their “street dirt” isn’t introduced into those areas. Hard surfaced flooring rather than carpeting is desirable to make cleaning easier. Surface dusting and floor cleaning should take place on a regular basis and should be conducted without solvents or any other substances that have not been tested and found archivally acceptable.

Risk reduction techniques include using proper temperature and humidity levels for the preservation of the materials which, coincidentally, are levels that do not provide a hospitable environment for the critters. Pre-storage inspection and fumigating collections may be needed—but careful and knowledgeable fumigation so that the process to rid the collection of the problem doesn’t damage or destroy the collection itself! Good housekeeping, of course, will remove the other enticements of food or water that attract the pests. Finally, if there is a problem, use an integrated pest management system that first identifies the specific problem and seeks to solve only it. This avoids introducing broad-spectrum pesticides that may be more than are needed.

Discs are traditionally stored vertically to prevent warping and to prevent stacking too much weight in a pile of discs and causing breakage in the lower ones. However, in my opinion and based on observing what I believe to be stress fractures in some shellac-type pressings, the archivist should consider the various types of discs in a collection and make reasoned positioning decisions based on understanding the nature and structure of individual types of items. Glass-base instantaneous discs are very different from vinyl pressings and some should and could be stored vertically and some horizontally.

One school of thought on tape winding for storage suggests playing the tape through from end-to-end and leaving it unrewound. Assuming the machine is properly adjusted and aligned, this should result in a smooth and uniform tape pack with even tension throughout. Leaving the tape in this tails out orientation means that should there be print through of the signal, that problem will be audible as an echo with the ghost signal following the strong signal. If left heads out and print through develops, it will be a precho (this is a made-up word, a contraction for “pre-echo”) with the ghost signal heard before the strong signal which is more distracting to the human ear and human mind.

A frequently asked question has to do with the need for periodic winding of linear media like wire and tape. There seems to be as many schools of thought as there are audio archivists and their opinions include:

In new facilities or facilities to be renovated, consideration should be given to compact shelving in order to maximize the amount of material that can be stored per square foot in the expensive to construct and expensive to operate environmentally controlled and protected vault space. Don’t forget about floor loading, because compact shelving significantly increases it!

With regard to intellectual content, there are established rules and procedures for describing audio recordings that should be used. It is possible that in some kinds of collections, especially those containing unedited or untitled items, a name or number will have to be provided by the cataloger using a system that matches the system already in use with the collection or the institution. Whatever naming system is used, it is clear that individual media and individual containers should both carry that identification, and the marking system used should be archivally acceptable.

Consequently, in my opinion, the answer is to take a page from modern warehouse practice and develop a random location storage system. Such a system is one that takes into consideration the variable factors of environmental needs, size, positioning, etc. and assigns items to the next available shelf space that meets the requirements. Computer software can be developed or may already exist that can take into account all those variables. Bar codes or other automatic identification systems (AIS) can be used to identify the items as well as identify the shelf locations so the entire process can be virtually error free because it does not depend on frequent keyboarding of information.

In summary, then, audio collections are like some people’s lives: full of risk. It is our job as collections managers to know the risks to our media, our equipment, our standards, and our software, and to take steps to reduce or avoid them. Risk-reduction may be a full time job in your shop!

This paper represents work carried out for a federal government agency and is not protected by copyright.