St Paul's Cathedral and dozens of other buildings in Melbourne's CBD are being defended from graffiti with a coating that repels paint, but authorities are still losing the war against "recidivist" offenders whose tags are verging on household names.

One of the newest tools used by the City of Melbourne to tackle graffiti is a shield or guard that stops spray paint penetrating into stone walls and other surfaces.

Melbourne City Council graffiti removalist Ben Ivory working in a laneway near Chinatown. Credit:Eddie Jim

The coating is used to protect 54 sites around the central city, following persistent attacks on churches, heritage statues and commissioned murals.

The council keeps a record of every tag removed from Melbourne's streets, and though the data is yet to be extensively analysed, it reveals the most damaging graffiti vandals go by the aliases Nost, Pork and Lamb – whose tags can be seen sprayed all over the state.