Video

Shown in the videos above is an actual cornice being steam cleaned this shows how effective this process is.  The whole area is sealed before the process starts to prevent damage to other areas of the room. 

This video was taken at:-

29 Wellington square
Chelsea
London.

It is a Grade 2 listed building and this work was carried out on February 27th 2014.

The cornices date to 1840 and have never been cleaned or striped