A video of a Jacobean portrait being restored has mesmerised Twitter users.
The painting was bought by Philip Mould, art expert and host of the BBC One show Fake or Fortune, from a private collection at auction.
It features a 36-year-old woman wearing an elaborate red gown, dated at 1617.
Mould told the Press Association:
The general feeling was that the condition was so bad on the surface that it was irrecoverable.
What happens is that mastic varnish, otherwise known as the tears of Chios, naturally degrades, going yellow with time. If you leave a picture long enough it becomes yellow and almost opaque.
Secondly, if a picture is in an area where there is smoke, either from a fire, cigars or a kitchen, that can also greatly darken the varnish.
You will see on the painting, there are about eight or nine tests all over the surface, very carefully working out that crucial balance between taking off the dirt and the varnish (which is what you do when you clean a picture) and not affecting in any way the pristine paint layer beneath.
He tweeted a clip of the restoration:
Generally, people were entranced:
@philipmould Wow! What an unbelievably satisfying job that must be!