Artisans have raced the clock at one of Melbourne's most loved theatres to restore a 1920s mosaic floor that has been hidden under carpet for 50 years.

The workmen laboured up to 19 hours a day for three months to return the elegant feature, created for the Forum Theatre's opening in 1929, to its former glory.

Melbourne-born, Italian-trained mosaic artisan Fabian Scaunich says the once broken and dirty floor of 200,000 mosaic pieces will be ready for the Comedy Festival launch at the Flinders Street theatre on March 28.

Mr Scaunich and two Italian workmates lifted 40,000 of the most battered pieces, and brushed and washed them.