Rapport

FFI-RAPPORT 16/00707

unless the temperature and relative humidity level get too low, higher levels than normal will

cause more damage than lower levels. If, however, they do get too low, this may cause some

changes to the mechanical properties of the piqlBox and the piqlFilm. The polypropylene (PP)

of the piqlBox is not notably vulnerable to changes in humidity, but lower temperatures will

cause brittleness in the material.

The polyethylene terephthalate (PET) of the piqlFilm, on the

other hand, is affected by both lower temperatures and relative humidity. It will also cause

brittleness to the point where the material might break, much like a cold rubber band.

addition, lower levels of humidity may cause static on the piqlFilm due to a slight contraction of

the emulsion layer where the information is written, which might cause difficulty in focusing

the images in the piqlReader [27]. Fortunately, these effects can be avoided simply by

conditioning the piqlFilm properly, i.e. letting it thaw under controlled conditions, before it can

be handled. Piql AS has conducted extensive tests to this effect. PiqlFilms have been stored in a

Cryotank which holds liquid nitrogen with a temperature of -196°C and varying levels of

relative humidity for 24 hours before being defrosted under controlled conditions. When the

piqlFilms were read back there were little signs of damage to neither the piqlFilm nor the data

written on it.

Lower rather than higher temperatures and levels of relative humidity can also

have positive effects on the longevity of the piqlFilm or the piqlBox. Market ―best practices‖

when it comes to storing photosensitive films is in fact to keep the storage conditions very cold,

near freezing.

Higher temperatures and relative humidity can affect the security properties of the piqlFilm in a

negative manner, yet the increased levels required for the negative effects to occur are quite

high. The piqlFilm has been subjected to extensive testing to determine these adverse effects.

High temperatures and high levels of humidity can cause the piqlFilm to warp because of

shrinkage along the edges, and it may affect readability, in the sense that the information gets

blurred when the emulsion layer starts floating out [27]. The integrity of the piqlFilm would

thus be greatly compromised, as the data is lost and cannot be read again. Additionally, in an

environment with higher levels of relative humidity there is a possibility of growth of

microscopic blemishes on the piqlFilm due to oxidation of the silver halide. Fungi may also

start to grow on the piqlFilm [27]. However, the tests conducted by Piql AS in collaboration

with other Consortium partners show that the temperatures required to generate these effects are

very high. The piqlFilm can withstand temperatures up to 85° Celsius at a relative humidity of

50 % percent for 23 weeks before there is a loss of mechanical properties which affects the

readability of the piqlFilm.

There are few plausible scenarios where such conditions exist over such a long period of time.

Additionally, our calculations show that the increase in temperature and relative humidity when

the environmental control systems are not functioning is modest, from 0.02 to 0.1° Celsius an

The properties and qualities of the piqlBox and piqlFilm were discussed in a telephone meeting with Espen Ommundsen, Principal

Researcher at Norner AS, and Yvonne Hed, Researcher at Norner AS, on 17.09.15.

Ibid

The information regarding the Kryolang project was part of an email correspondence with Janita Flo, Lab Manager at Piql AS, on

04.05.16.

The information regarding the test results of the piqlFilm’s exposure to high temperatures over extended periods of time was part

of an email correspondence with Svein Jamtvedt, Principal Researcher at Norner AS, on 27.05.16.