The painting has been restored at least twice before. The first time occurred in 1975, following an attack wherein a man wielding a bread knife slashed the masterpiece and claimed he “did it for the Lord.”
“Anybody who attacks ‘The Night Watch’ must be a lunatic,” Dr. P. J. Van Thiel, the museum's acting director at the time, told The New York Times
The second restoration happened in 1990 after a man sprayed acid on the painting. The damage was repaired, but it appears it needs an update. A white haze has begun to appear on some parts of the painting, especially in the area surrounding the knife damage, where it is bleaching out the figure of a small dog.
The restoration project is expected to be a multi-million-euro job and will take several years to complete. “As we say in Dutch, conserving paintings is a monk's job. It takes a lot of patience,” Dibbits said.