Transcript of the video "Time-lapse Video of Deterioration: Two Iron Keys, Incorrect Relative Humidity & Pollutants"
Length of video: 00:01:50
[No audio or voice over in this video]
On screen: two keys are shown side by side.
Two iron keys were air abraded to remove any existing corrosion.
One key was kept clean and handled only with gloved hands.
The other key was made dirty by handling it with bare hands, and exposing it to salt and dust collected from a household vacuum to simulate unfavourable handling practices and poor pollutant control.
Both keys were placed in 85% relative humidity (RH) to simulate a damp environment. Photographs were taken every 30 minutes for a month.
[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].
After 1 day in the damp environment, there is no visible corrosion on the clean key. However, there are spots of visible corrosion on the dirty key.
After 18 days, the clean key has some small spots of corrosion. By contrast, the dirty key on the right is nearly covered with brown corrosion. The corrosion is spalling off the key, and landing on the surface below the key.
[The time-lapse sequence ends]
The clean key is shown before and after being in the damp environment. The light corrosion on the clean key after being in the damp environment demonstrates that high relative humidity on its own will corrode metals.
Next, the dirty key is shown before and after being in the damp environment. The heavy corrosion seen on the dirty key after being in the damp environment demonstrates that high relative humidity plus pollutants will corrode metals even faster than the damp environment alone.
Avoid damp, over 75% relative humidity, to prevent rapid corrosion. For metals, the lower the relative humidity, the slower the corrosion.
Wear gloves during handling.
Avoid exposure to dust and salts.
[Canadian Conservation Institute signature and Canada wordmark]