Attach a soft-bristle upholstery brush to a vacuum hose. Vacuum dust and dirt off the banana rush backs, seats and arms. Turn the chair over and vacuum it from the underside.
Pick out dirt carefully with a wood skewer or sharpened dowel from the area where the chair back meets the seat and arms. Brush dirt away with a paintbrush.
Wet a natural sea sponge with clear water and squeeze out the sponge so it remains damp. Wipe the banana rush chair's seat, back and arms to remove stuck-on bits of dirt. Turn the chair over and wipe the underside.
Spray the banana rush chair seat, arms and back with plain water from a spray bottle to prevent the materials from drying out and cracking. Spray enough water to dampen the banana rush without saturating it. Repeat this procedure every four to eight weeks, depending on the humidity in the house.
Place banana rush chairs in an area of the room that is out of the direct sunlight. Sunlight is damaging to banana rush and causes it to fade and dry out. Keep banana rush seats at least 24 inches from radiators and baseboard heating.
Dip the corner of a rag into paste furniture wax and apply a very thin coat over the entire banana rush chair. Follow the weave to prevent a waxy buildup in the chair's crevices.
Set a banana rush chair on a tarp outdoors. Mix 1 cup of turpentine with 2 cups of boiled linseed oil. Dip a rag into the mixture and wipe it onto a banana rush chair that is overly dry or beginning to crack. Continue to wipe the boiled linseed oil and turpentine onto all surfaces of the chair until the banana leaf and rush no longer accepts the mixture. Let the chair sit for one to two hours. Wipe the excess mixture off the chair with a soft, clean rag.