Frequently Asked Questions
How do I make a time capsule?
The container must be strong and airtight
to prevent the entry of moisture, dirt
The container should be non-corrodable.
By far the best modern material for burial
is stainless steel which is relatively
cheap, easily fabricated and stable in
The capsule should be welded shut (difficult
to open but will provide an excellent
seal if the welding is done well). Lead-tin
solder should not be used as it will deteriorate
in the ground, allowing water into the
capsule. Screw on caps can be used as
opposed to welding or alternatively wing
nuts can be used to clamp the lid in place.
However, screw threads can 'seize' when
left under pressure for a long time, making
them difficult to unscrew.
Bottles made of stable glass may survive
very well, but are prone to being broken
due to shifting foundations, frost or
carelessness at the time of retrieval.
The use of plastic containers is open
to debate. Not much is known about the
long term stability of most plastics under
burial conditions and it is possible that
they may crack under extreme conditions
and the seals may also be prone to wear.
Large diameter high density polythene
pipes have been used. The end caps can
be heat sealed or threaded caps sealed
with Teflon tape.
PVC (polyvinyl chloride) pipe should
not be used for time capsules as it will
eventually deteriorate and release acid
affecting the contents of the capsule.
Before burying, the capsule should be
wrapped in a waterproof membrane.
Interior of the capsule
Prior to sealing the capsule it should
be packed with a 2.5"-3" layer
of ceramic wool fibre, completely surrounding
the documents, to protect them from the
heat of welding.
The environment inside the time capsule
should be dry and oxygen free. After welding,
oxygen should be removed by flushing the
capsule with dry nitrogen through a small
hole left for the purpose. The nitrogen
will displace the oxygen in the container.
The hole should be sealed rapidly.
Silica gel or another humidity control
system will help control the humidity
in the capsule.
Contents of the capsule
Non paper objects:
Objects which can decompose and thus give
off corrosive substances should be avoided.
This includes all plant, animal and insect
specimens and anything containing batteries.
Polyvinyl acetate (PVAC) or polyvinyl
chloride (PVC) will release acid as they
age and should be included only with extreme
caution. Objects should be wrapped in
acid accepting paper, buffered acid free
tissue or washed cotton. These materials
will absorb acid.
Rubber also deteriorates over time, releasing
sulphur. Materials made of rubber should
not be used in capsules.
Textiles should be clean and insect free.
Most textiles survive well in a nitrogen
All wood, especially oak, gives off acid.
It should be kept away from any electronic
or metal items before they are inserted
into the capsule.
Metal items should be free of visible
corrosion and in sound physical condition.
Avoid polishing items before they are
inserted into the capsule.
Electronic devices should have their batteries
removed and discarded. Leave instructions
on the voltage and current requirements
of the device. Solar powered devices are
a useful alternative. Paper instruction
manuals should be stored away from anything
Use archival quality audio and video
tape. Bear in mind that the equipment
necessary to play back these items may
not exist when the capsule is opened!
Permanent paper (i.e. paper of an archival
quality) should be used. If permanent
paper is not used, all documents should
be deacidified to help prevent chemical
degradation. A professional paper conservator
should be employed to do this.
Newsprint is destroyed rapidly by acid
residues left in the paper from the manufacturing
process. Newspapers must be deacidified.
If typed documents are to be included,
a pure carbon type writer ribbon should
be used. If hand written, archival record
ink, not biro, should be used.
Before being placed in the container,
the documents should be dried so as to
reduce the relative humidity to 30%.
Each artefact or set of documents should
be placed in an inert polyester bag prior
to insertion into the capsule. This will
ensure that dissimilar materials are isolated
from one another.
Black and white photographs should be
used in preference to colour material.
All colour photographic material has
a relatively short life and may be in
danger of darkening or fading. Polaroid
photographs should not be used even in
short life capsules due to their instability.
Burying the capsule
Place the capsule in a cool, dry location,
where it will not be exposed to great
fluctuations in temperature.
Time capsules are most commonly found
buried below ground level in the foundations
of buildings. A drained concrete or brick
vault lined with fibreglass should be
built in order to minimise temperature
fluctuations and prevent access of water.
The site of a time capsule is often marked
in some way. The International Time Capsule
Society exists to maintain a register
of all known time capsules, to promote
research into the history, variety and
motivation of time capsule projects, to
educate and raise awareness of time capsules
among the public and scholarly community
and to act as a clearing house for information
about time capsules.
For more information contact:
Dept of Ethnography
The British Museum
Museum of Mankind
6 Burlington Gardens
Tel: +44 (0) 20 7636 1555 ext 8027
Fax: +44 (0) 20 7323 8013