Remove the knobs and other hardware from the cabinet. Put painter’s tape around the perimeter of wall-mounted sections of the cabinets to protect the wall. Lay tarps on the floor around the base of the cabinets.
Hand-sand the cabinet surface with 100-grit sandpaper, to dull the shine. Don’t try to remove the existing finish, just the shine.
Use your paint brush to apply refinishing glaze thickly over each flat span of the cabinets.
Let the glaze sit for about five minutes, watching the surface of it for indications that it’s starting to dry. It will start to get dull and less shiny.
Wipe off the glaze with dry rags before it’s completely dry. Wipe lightly, so the glaze is taken off just the flat spans but remains partly on the cabinet in the inner corners and other tight spots. It should create the effect of age, with the underlying finish showing through the glaze in most of the surface but not all of it.
Let the glaze dry for 12 hours.
Brush varnish over the whole cabinet to seal in the glaze. Let it dry for six hours. Apply a second varnish layer. Reinstall the hinges and hardware.