Photograph the hob from directly above before lifting anything, because a wide Emilia carries several trivet sections that are not interchangeable. Soak the enamelled parts flat in a non-caustic degreaser and dry all cast iron by hand.
An Emilia hob is the top of a wide freestanding Italian range, and the number of separate pieces is what makes it different from a built-in cooktop.
Count the pieces before you lift them
A 900mm or 1000mm Emilia carries trivets in several sections across its width, plus burner caps and crowns in three or four sizes. On a hob this wide the sections flanking a central burner are frequently cut differently from the outer ones, and they look identical until one of them rocks.
Photograph from directly above and lay the pieces out in the order they come off. It takes ten seconds and it is the difference between an afternoon's work and a fortnight of pans sitting unevenly.
The general method
Soak the trivets and enamelled caps flat for an hour in hot water with a non-caustic degreaser, in a tub lined with an old towel so cast iron does not chip the porcelain. Work them with a stiff nylon brush rather than wire. Our cooktop cleaning guide covers clearing ports and looking after the ignition electrodes.
Dry every cast iron piece by hand, immediately, because exposed iron rusts fast in Sydney and a piece left wet once tends to keep rusting at the same spot.
Part of the range below
On a freestanding Emilia the hob is not a separate appliance. It shares a fascia with the Emilia oven beneath it, which means anything sprayed on the cooking surface runs down onto the controls for the whole machine.
Spray onto the cloth. On a range this size the control panel is the most visible part of the appliance and faded markings are permanent.
Bought for the look, and kept for it
An Emilia range is chosen rather than inherited. Somebody wanted a wide Italian gas hob and paid for it, which means the appliance is usually kept for a long time and the owner notices how it presents.
That has a practical effect on where effort is worth spending. On a rental hob the cavity and the trivets are what get inspected. On an Emilia the trim, the fascia and the evenness of the burner caps are what the owner looks at every day, and a hob where one cap sits slightly proud reads as wrong from across the room even though it cooks perfectly well.
So take the extra minute on reassembly. Seat each cap deliberately, check they sit level with one another rather than merely lighting, and wipe the fascia last with a clean cloth. On an appliance somebody chose, presentation is part of the job rather than a nicety.
What actually goes wrong
Trivet sections back in the wrong positions, so pans rock.
A burner that will not simmer, from a cap on the wrong crown.
Faded fascia markings, from cleaner sprayed on the hob.
Rusted cast iron, dried by air.
Should you do it yourself?
Do it yourself, lifting the burners every month or two.
Get someone in if the hob base has set hard, or for the whole range in one visit, which is how most owners approach it.