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When all the items to be included in the capsule had been gathered together they accounted for about 60% of the capsule's 500,000m³ capacity. Numerous storage trials confirmed that there was sufficient space to store all these objects while keeping items of a similar nature together and taking into account the storage needs of individual items.
These individual needs posed the most challenging problems. For example, every object would need to be suitably sterilized and disinfected in order to prevent the growth of mould and bacteria. The atmospheric and sealing conditions had to be such as to prevent changes in quality and colour. Special treatment would be required for items in which some deterioration was inevitable. And, not least, new technologies would have to be found for the treatment of books, film, magnetic tape and other media.
Research into these and other preservation problems was initiated by the technical committee. A number of technical sub-committees considered items in specific fields, such as biology, or specific materials, such as rubber. The Research and Development Centre set up a preservation department which collaborated with the research institutes of Matsushita Electric and other bodies in finding solutions to all kinds of problems, both large and small. The results of their work are summarized here:
Dust is a carrier of mould and bacteria. Therefore every object in the capsule had to be handled and treated under the most sterile conditions in a dust-free environment. Every object was thoroughly sterilized before storage using the most appropriate of several sterilization methods, including ethylene oxide gas, radiation and heat. Since many of the objects were vulnerable to heat, the majority were sterilized with ethylene oxide. There was some anxiety about this method since it requires a relative humidity of about 40% and temperatures between 30-50ºC. Moreover, carbon dioxide or fluorocarbon must be used as a diluent gas. Under test, however, it appeared that in almost every case ethylene oxide treatment would not accelerate deterioration or it would have negligibly damaging effect. In cases where ethylene oxide treatment was inadvisable, the objects were sterilized by gamma radiation.
The construction and material of the capsule body would protect the contents against the intrusion of humidity, heat, ultraviolet light, oxygen, carbon dioxide and harmful gases. The capsule would be filled, after sealing, with argon gas. However, additional atomospheric control measures were required, particularly in relation to interior humidity.
A large quantity of zeolite was used to de-humidify the interior of the whole container. The environment of every object needing a special level of humidity was adjusted before the object was individually sealed, using zeolite and silica gel. Argon gas with an RH of 40% was provided for film and lacquered objects. Air with an RH of 5% was provided for seeds. Samples containing moisture were sealed within fused quartz glass tubes; unlike ordinary glass, quartz does not deteriorate in the presence of moisture. In the case of rubber, vinyl chloride and leather objects (where there is a danger of deterioration affecting other objects) these were sealed individually in steel foil bags, plastic film or quartz glass tubes.
After every kind of material had been studied closely, a few materials were determined to be extremely prone to deterioration. Wherever possible, these materials were replaced with others having a similar function or appearance. In cases where replacement would destroy the whole purpose of their inclusion, deterioration was accepted and the objects concerned were given special treatment. Let us examine some of these special cases and the ways in which they were treated.
At the present time, the only satisfactory way of prolonging life in living organisms is to keep them in a dormant state at a temperature of minus 20-30ºC. Since the time capsule was to be buried underground at a temperature of around 17ºC (at the time of burial the temperature was 17.5ºC), the environment of the capsule prevented these conditions from being met other than by the provision of some kind of refrigeration system. To construct a refrigeration system which would operate for 5,000 years was out of the question.
Under these circumstances, and hope of servival for 5,000 years could only be entertained in the case of lotus seeds and certain microorganisms. However, it was felt that all the seeds and microorganisms in the capsule could provide a very valuable academic record and the range of specimens was made as wide as possible. Particular emphasis was placed on enzymes, given their vital role in all life processes. In every case, biological specimens were prepared most carefully according to their individual atomospheric needs. Prior to sealing in quartz glass tubes, each specimen was either freeze-dried or dried after storage at low temperature.
A certain pessimism about the survival of seeds and bacteria was balanced out to some extent by the potential of Capsule No. 2, which will be opened for the first time in the year 2000 AD. This capsule contains two stocks of bacteria and phage which can be cultivated in turn during the 100-year opening cycle of the capsule. Instructions to this effect have been laid down in the examination procedures for Capsule No. 2.
As far as the higher forms of life are concerned, the capsule contains a great deal of reference material of various kinds. Books contain detailed descriptions of flora and fauna. The sounds made by various animals are recorded on magnetic tape and there is film of Japanese birds and animals threatened with extinction. Insects have been encased in resin. The record of living things on this planet in the year 1970 is very comprehensive.
In the case of natural rubber, long-term preservation is possible as long as the material is pure and there is strict control over the process of vulcanization. The same holds true for synthetic rubber. However, in the case of mass-produced rubber components forming part of common objects, it was not possible to have any control over production quality. These parts can be expected to produce separated sulphur as a result of excess vulcanization. In order to protect the environment of the capsule, objects containing such parts were sealed in quartz glass tubes. Vinyl chloride made by the conventional process tends to decompose and produce chlorine over a long period of time. These items were treated in the same way as mass-produced rubber.
Leather has a very long history. Examples of leather documents used by the ancient Egyptians have survived for 4,000 years; however, these are in a fragmentary state and later examples of leather footwear and clothing show varying degrees of decay. Leather is composed of animal protein, albuminous fibres, gelatin and enzymes which break down into amino acids over a long period of time. At present, despite improvements in tanning processes, there is no known method of preventing or retarding the process of decay.
Nevertheless, since the 20th century may be the last in which leather is used on a large scale, it was felt to be important to include examples of leather products. The best that could be done in the way of preservation was to offer the protection afforded by the environment of the capsule itself. All items made of leather were stored together in a sealed inner compartment.
The purpose of building a large capsule was to include many full-sized objects, but it would have been impossible to cover the whole spectrum of life in 1970 without recourse to various forms of compact records such as books and photographs. The sound and movement of life today could only be conveyed by film, recorded tape and phonograph records.
Over 100 items of record media were placed in the capsule. This figure includes original paintings, books, newspapers, messages and reports, etchings, photographs, tape and phonograph records, 16-mm film with soundtrack and microfilm. The range of media was deliberately made as wide as possible in order to demonstrate the present level of printing and recording technology. Age-acceleration tests in conditions simulating those inside the capsule were conducted on all the media; the complexity of this study and the search for preservation methods can only be described briefly here.
During manufacture, Japanese and Western papers absorb very small amounts of oxygen and moisture. It is these constituents which provoke the brown and brittle characteristics of very old paper. Although oxygen and moisture could be eliminated from the capsule itself, nothing could be done about their presence in paper – or for that matter, in fibres and textiles.
When various papers were tested under reduced pressure for two hours at a temperature of 120ºC, all exhibited some degree of browning, loss of strength and lowered molecular weight. Papers that suffered the least deterioration were those composed of long and rather thick fibres and, of these, ganpi washi (a hand-made Japanese paper, from the plant Lychnis coronata) and a Western paper used for insulating high-voltage cables gave the best results. A certain degree of browning would be inevitable over the years in both these papers, but to nothing like the degree expected of ordinary Western papers. Ganpi wash, coated with white pigment, was used for the four picture scrolls "Japanese Manners and Customs." (S-16-1, 2, 3 and 4).
Not all the printed media in the capsule were original works and when it came to mass-circulation magazines, for example, two main precautions were taken. Firstly, it was required that these magazines were printed on white paper using black ink so as to ensure legibility despite advanced browning of the paper. Secondly, each was screened for undesirable constituents in either the cover or the binding.
Numerous tests were done on pigments and paints and it was concluded that synthetic pigments containing only a small amount of impurity were sufficiently stable. The disadvantage of these synthetic pigments is that they are available in only a limited range of colours. Of all the paints tested, shiniwa paints, in which the pigments are dispersed in glass, gave the best results.
After pigment, the second major constituent of paint is the binder and this binder varies according to the end usage of the paint. Various binder-pigment formulae were tested in order to find out which were most suitable for printing and painting. As far as printing was concerned, the highest grade of printing ink was found to be acceptable. But for the purposes of Japanese-style painting, in which the conventional binder is glue and water with alum as an auxiliary agent, it was found that glue and alum interact progressively with paper, and low-grade glue is particularly damaging. This problem was resolved by mixing shiniwa paints with the highest grade of glue available, shikanikawa (processed from the bones of deer), and the very minimum quantity of alum. When the colour range of synthetic pigment alone was insufficient, small amounts of conventional but unusually stable paints were added to give the required colours.
The printed works in the capsule include original works as well as existing books and magazines. These books and magazines were, in most cases, stored in their original format. In theory; there was enough space in the capsule for most of the original works to be printed and stored in standard format also; the main reason for using microtechniques was to show the level of our achievements in this field.
The most sophisticated microprinting technique is the electron beam exposure method in which the letters are legible only through an electron microscope. One hundred pages of standard-sized material can be inscribed on a single silicon plate 25mm square. However, since the scanning device is bulky and the amount of material involved did not necessitate such extreme reduction in size, it was decided to use conventional microtechniques in which the print can be read with the naked eye or at low magnification. Four representative microtechniques were selected: Etching on stainless steel plate; microbook; etching on silicon plate; microfilm.
Etching on steel plate can be read by the naked eye. It was used for "The 1970 Rosetta Stone" (S-31-1-1), a message inscribed in Japanese and the five United Nations languages of Chinese, English, French, Russian and Spanish. The opening instructions, and the technical drawings of the capsule and its burial positions, were similarly inscribed on the same material.
The microbook is an example of advanced printing technology. It is possible to print letters only one tenth of a millimetre high but since such a degree of reduction was not needed, the printed letters were merely reduced to one-quarter their original size. These letters are clearly legible through a magnifying glass. The paper used for microbooks was an India paper which had scored highly in the tests for browning mentioned earlier in this section.
Etching on silicon plate is a new method which makes use of techniques developed for the photo-etching of printed circuits. The rate of reduction can be very great, but in this case the text was reduction-printed to a size legible through an ordinary microscope. Microfilm was used for the reproduction of standard works that were out of print and for certain instructions and diagrams. The treatment of the film medium is discussed below.
At present, no other commercial product surpasses silver halide emulsion film in resolving power and gradation. Depending on the purpose of the film, selected silver halides are emulsified with gelatin and the prepared emulsion is spread in a uniform coating on the film base. Both of the main constituents of the emulsion pose long-term preservation problems.
If gelatin is allowed to become dry it contracts, cracks and, in the case of film, peels off the polyester base. This problem can be avoided quite simply by maintaining humidity above 30%. However, moisture in the gelatin accelerates inter-reaction between oxygen contained in the gelatin and the grains of developed silver. As a result of oxidation, the image becomes transparently spotted with silver compounds ; progressively the image fades and ultimately it disappears altogether. The maximum life of black-and-white film developed by the conventional process is 500 years at best. Since the life of de-hydrated film would be even shorter due to cracking and peeling, some radical change of process was required in order to preserve the film in conditions of 30% humidity while lengthening the life of the image. This process was gold-treatment.
After the film had been developed and fixed it was passed two or three times through a tank containing a solution of gold salts. The gold replaced the silver particles on the film to sufficient degree to prevent oxidation. This treatment was given to microfilm and motion picture film – in the latter case, given the importance and immediacy of moving images, gold-treatment was a particularly significant development.
Gold-treatment cannot be applied to photographic paper because, unlike the polyester base of film, the paper absorbs moisture and chemicals. The washing process is extended and difficult and, overall, the results are not satisfactory. For this reason, all printed photographs were microfilmed and stored in that form ; written images were stored as negatives and all other images as positives.
Film and printing paper for colour photography show severe fading within only 50 years, in some cases after 10 years. This is due to the instability of conventional dyes. Since colour film with stable dyes is not available and gold-treatment cannot be applied to colour film, dye-transfer was used for the reproduction of colour images. Dye-transfer is a method of colour photography which is intermediate in technology between photography and printing. It involves the use of three separation negatives in register - red, green and blue - and stable dyes and pigments to colour in each stage of the positive print. After careful finishing and washing, the result is a faithful reproduction of the original colour image. The dye-transfer process was used for actual-size photographs of paintings done by Japanese school children on the theme "To the People 5,000 Years Hence" (A-3-2). The photographs will survive infinitely longer than the original watercolour paintings, or colour photographs produced by the conventional process.
There are three practical methods of recording sound: Optical recording, represented by the optical band applied to motion picture film; magnetic recording using magnetic tape or wire; and mechanical recording, the phonograph record. Of these, the most practical and popular for domestic use are magnetic tape and phonograph records, both of which provide excellent fidelity when used with recording and playback equipment of high quality. For the purposes of the capsule, tests were conducted as to the feasibility of using several representative recording systems.
The motion pictures in the capsule have an optical band on the film itself. This band contains a photograph of electrical impulses which can be "read" by a device in the film projector and translated back into sound. Although gold-treatment applied to the film would protect the band from oxidation, there was some uncertainty as to its effect on the quality of the sound. Under test it was discovered that the replayed sound, though clear, was somewhat hard in tone. Despite this minor drawback, it was decided to use the conventional sound-on-film system.
Initial discussions about magnetic recording systems centred on the choice between tape and wire. There was no major anxiety about the loss of magnetic properties since there is evidence of magnetism – in rock, for example – surviving for tens of thousands of years. Having decided to proceed with tape, which is superior to wire in fidelity and clarity, it was necessary to investigate ways in which to preserve its physical characteristics. These characteristics are dependent on the proper dispersion of ferric oxide in a suitable binder. A suitable binder was found and the magnetic coating was applied to a stable and durable polyester base. After acceleration heat-treatment, it appeared that the drop in recording level within the audio frequencies would be no more than 2-3 decibels at 10kHz after 35,000-60,000 years . This negligible deterioration would result from changes in the physical characteristics of the binder. As a precaution against magnetic induction occuring between the layers of wound tape, the polyester base was adjusted to 50 microns.
In the course of testing magnetic tape it was found that high frequencies are the frequencies most seriously effected by long-term changes in physical characteristics. This indicated that videotape, which requires stable performance at high frequencies, would not be a suitable medium for use in the capsule.
The phonograph record is one of the oldest surviving recording media and it remains one of the most popular, especially in home fidelity systems. The record itself is durable and easy to use and the reproduction equipment is relatively simple. Nowadays, the records are made of vinyl chloride; they are structurally simple but the production process has many disadvantages as far as long-term storage is concerned. The filler and plasticizer have a tendency to separate over a long period of time, creating an unacceptable amount of disturbance in reproduction quality.
However, phonograph records are so much a part of the life and leisure of our age that by some means or other they had to be included. The means was a complete change of material, to nickel silver electro-plated with gold. These "gold" phonograph records are impervious to corrosion yet capable of normal stereophonic reproduction.
The capsule contains sufficient data and equipment to enable all the media to be transcribed. For tape, there is a scale-drawing of a tape recorder and three tape recorder heads. For records, a drawing of a player and a semi-conductor cartridge. Photographs and drawings of a 16-mm film projector and a microfilm reader are also included.
After every object and record medium had been suitably treated and sterilized, it was packed in one of the capsule's 29 stainless steel compartments. The internal design of the capsule (see Section III : Internal Plan of the Capsule) divided the space into units of varying capacity according to the requirements of different categories of objects and media.
Three compartments were hermetically sealed : No. 27, containing film and items printed on conventional paper, and Nos. 8 and 9, containing leather, rubber and other materials subject to decomposition. The uppermost compartment, No. 29, fits into the neck of the capsule. It contains a complete list of the contents, records relating to the sponsors and the construction of the capsule, drawings and devices for transcription of the record media, the 1970 Rosetta Stone and a Japanese flag.
Each of the compartments was wrapped with ceramic wool of aluminosilicate (Si2O-Al2O3). This material provides a perfect inert packing between all the metal surfaces within the capsule, preventing direct metal-to-metal contact and localized pressure.
In December, 1970, the last compartment was carefully fitted into the neck of Capsule No. 1. For those who watched, it was a thoughtful moment. If this capsule is allowed to rest in peace, its contents will not be seen again for 5,000 years.
The contents of this site are excerpted from THE OFFICIAL RECORD OF TIME CAPSULE EXPO'70(March 1975). Please note that company and organization names may differ from those of the current ones.
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