Use a Philips-head screwdriver to remove the screws from the hinges holding the cabinet door in place, then remove the door from the cabinet body. Unscrew the hardware from the cabinet, and set it aside for reattachment after you complete the antiquing process.
Clean the cabinet and the cabinet door thoroughly with a mix consisting of one-half cup TSP (trisodium phosphate) mixed with two gallons of warm water in a large bucket. Use a sponge for cleaning cabinet surfaces, taking care not to saturate the wood and cause warping. Rinse with clean water, and then pat the cabinet and door dry with a rag. Place the door onto a drop cloth for painting.
Mix one part white glaze with one part gray paint using a wooden stir stick in a paint pail to create your antiquing mix. The glaze will appear white when mixing, but will dry clearly on the cabinet, leaving only the translucent gray of the paint behind.
Dip a sponge into the glaze mixture and apply the glaze to the cabinet door Use a circular motion to apply the glaze in a light layer onto the door. The glaze, upon drying, will dull the paint on the cabinet door while making it appear slightly weathered by age as well.
Wipe the majority of the glaze from the door immediately with a rag to leave behind only a light layer of the coating. Leave a bit more of the glaze in any recessed areas of the cabinet door, however, to help with the illusion of natural aging in the piece.
Use the same process that you used to apply the glaze to the cabinet door to cover the cabinet body with a layer of glaze as well. Make certain that you get the face of the body of the cabinet as well as the sides, covering all surfaces that are visible to viewers.
Allow the glaze to dry overnight before reattaching the fixtures to the cabinet door and rehanging the door back into place.