Transcript of the video "Time-lapse Video of Deterioration: Oil Painting, Incorrect Relative Humidity"
Length of video: 00:01:51
[No audio or voice over in this video]
An oil painting, several years old, on sized canvas, with no backing board was placed in a chamber at 50% relative humidity (RH) and keyed out tightly so that any changes in tension would be emphasized.
The painting was photographed in normal light (lit from the front with a light source that emits no heat).
Then it was photographed again with transmitted light (lit from the back, with a light source that emits no heat) so that light shines through any cracks.
[Two photographs of the same painting with different lighting are shown side by side.]
The relative humidity set point in the chamber was dropped in three steps to simulate a drop in RH to very dry conditions:
- 50% to 35%
- down to 25%
- down to 5%
[A graph shows conditions for the time-lapse sequence with time on the x-axis and percent relative humidity on the y-axis, showing that the painting spent 3 days at 35%, then 4 days at 25%, then 6 days at 5%.]
Let's watch the time-lapse…
[The time-lapse sequence begins]
At 50% RH
After 1 day at 35% RH, new fine cracks open up. Pre-existing cracks grow wider and longer.
After 3 days at 35% RH, there is a slight increase in damage at 3 days but most damage from 35% RH occurred within 1 day.
After 1 day at 25% RH
After 1 day at 5% RH
A pattern of concentric cracks indicative of a previous blow to the painting becomes visible. The cracks follow the direction of the heavy impasto.
[The time-lapse sequence ends]
The painting is shown as it looked before the relative humidity drop. As a comparison, the screen transitions to the painting as it looks after the relative humidity drop.
After the relative humidity drop, with normal light, the cracks are not visible, but with transmitted light, the cracks become apparent.
[Two photographs of the same painting with different lighting after the relative humidity drop are shown side by side]
Avoid very low relative humidity for paintings, as it will expand pre-existing cracks and can create new ones.
[Canadian Conservation Institute signature and Canada wordmark]