Time-lapse Video of Deterioration: Parchment and Iron Key, Incorrect Relative Humidity


Transcript of the video "Time-lapse Video of Deterioration: Parchment and Iron Key, Incorrect Relative Humidity"

Length of video: 00:01:46

[No audio or voice over in this video]

On screen: A piece of parchment with handwriting in poor condition, and an iron key, air abraded to remove any existing corrosion, were sprinkled with dust to simulate a collection space where some dust and spores are present.

[Two images of the objects appear side by side, with the left image depicting a light layer of dust on the objects]

The parchment and iron key were placed in 95% relative humidity (RH) to simulate a damp environment for 21 days. Photographs were taken every 10 minutes.

[A graph appears, showing conditions for the time-lapse sequence with time on the x-axis and temperature and percent relative humidity on the y-axis.]

Let's watch the time-lapse…

[The time-lapse sequence begins]

As soon as the relative humidity starts increasing, the parchment relaxes.

After a few days, the parchment begins to deform.

After 6 days, the surface of the key becomes dull and black corrosion spots appear.

After 12 days, white mould hyphae appear on the parchment.

After 17 days, the mould matures: black sporangia become visible.

On day 23, the relative humidity quickly returns to moderate levels. The parchment has suffered deformation during the period of high relative humidity.

[The time-lapse sequence ends]

The parchment and iron key are shown as they looked before being in high relative humidity.

As a comparison, the parchment and iron key are shown after being in high relative humidity.


Avoid damp, over 75% relative humidity, to prevent rapid mould and rapid corrosion.

Avoid relative humidity fluctuations to prevent deformation of parchment.

[Canadian Conservation Institute signature and Canada wordmark]

This video demonstrates how high relative humidity causes deformation and mould growth on parchment and causes corrosion on iron. This video was created by the Canadian Conservation Institute.

Cat. No.: CH57-4/17-2-2020E-MP4
ISBN 978-0-660-36440-7

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