Painting over the English language

The English language is constantly changing,  traditional sayings become obsolete, sometimes because of new developments in technology

 For example, a new paint is being used to paint the Forth bridge, a job that previously had to be constantly repeated because of the huge size of the bridge. Because the job was so repetitious, other repetitious jobs came to be described as `like painting the Forth bridge.’
The job of constantly painting the bridge has been ongoing for the past hundred years, but the work should come to an end in about four years. The Forth bridge is a rail bridge which spans the Firth of Forth in eastern Scotland.
There’s a similar British saying to this which is `like watching paint dry’, meaning a task which is so uninteresting and seemingly endless that it is like watching a coat of paint dry, a process which can take hours.
In theory this saying is also an endangered species because of the availability of quick drying paints. But in reality it can still be heard, so perhaps new technology doesn’t always have an adverse effect on the English language.
One painting-related saying which really does seem to have vanished into obscurity is the saying `painting the town red’, meaning to celebrate in a wild, abandoned way. It was often used by older people but is rarely if ever used by modern teenagers.
Another paint-related old saying is to `white wash over’ something. White wash is an old name for white (usually water-based) paint. This kind of paint was often used to paint the walls of buildings, quite often to hide defects  in them. 
Because it was used to hide defects, it was also used to describe an investigation or report, usually an official investigation or report,  which attempted to hide defects.  For example, if a government produced a report, and if someone suspected that it had defects, or was trying to hide something, they might claim “This report is a white wash!”
It is still sometimes used, but it is threatened by the phrase `cover-up’ , which also means a report, usually an official report, that is trying to hide something.   
One reason for the  decline of `white wash’ might be because simple white, water-based paints like this are often no longer used to paint the walls of buildings, and to cover up defects. They have mostly  been replaced by modern `masonry paints’, which are more effective. 
This is another  example of how new technology has helped to change the English language.