This is primer in aerosol form special for car body galvanized panels.

Alfa Romeo Rosso 130 paint in aerosol can. These can be easily ordered at every car paint shop.

Alfa Romeo Rosso 130 paint in aerosol can. These can be easily ordered at every car paint shop.

These are the hinges primed. A second layer will be applied after 24 hours.

Two coats of red paint sprayed with 24 hours difference between them.

Close-up of the upper hinge.

Close-up of the lower hinge.

The armrest and door card and has been removed along with the door check.

Wiring harness has been removed and the door is about to be taken away.

A view with the door removed. Note the A-pillar color mismatch which concludes that the painting process during production was done with the door on the car.

The upper hinge has been removed and the remains of seam sealer will be cleaned. Use masking tape to avoid damage on the wing.

Lower hinge has been removed.

This is the old and worn out hinge. Note the foil piece on the lower part of the hinge. Clean this foil with alcohol as it must be reused to the new hinge.

This is the old and worn out hinge. It is the pin that wears out and theoretically if one can press out the old pin then a new pin can make the hinge as new again.

Mask the area and spray a quick layer of red paint just to cover the primed area.

I have omitted to take more photos as the procedure is the same as done on the right side door.
Steps required 

Install the new hinges in position with the bolts hand-tight.
Install the door and adjust it carefully taking into account the door edges and alignment; once this is done tighten the hinges bolts as much as possible.
Remove the door, paint the area to match the rest of the paintwork
Install the door, fully tighten the bolts fixing the door to the hinge and restore door check, wiring, door cards etc.

Upper hinge painted and lubricated.

Everything back in place.

Final check of the door gaps and alignment.