I don't know about how the modern art world does it but varnishing a an antique painting is very bad. Varnish shrinks over time and pulls the paint with it, causing it to crack. I know one guy who works at a premier auction house. His job is to remove the varnish from rare paintings. You'd be amazed how many paintings turn up that were stolen from museums by the Nazis.
And by the way, that is some superb work!