Hardwood furniture needs only cleaning and, where the original colour is wanted, oiling. Softwood needs stain or paint, and iron and steel need rust removed and a primer before repainting.
Furniture kept dry over winter, or under a breathable cover, lasts far longer than furniture left exposed.
Garden furniture left outdoors weathers quickly, but most of it can be brought back with cleaning, minor repairs and a new finish. The treatment depends on the material.
Teak, eucalyptus, acacia and other dense hardwoods contain natural oils and last for decades outdoors without treatment. Left alone they fade to a silver-grey, which is a change of colour only and does no harm.
Dirt, algae and lichen are removed with warm soapy water and a stiff brush, working along the grain. A pressure washer on a high setting tears the soft fibres out of the surface and leaves it rough; a low setting held well back is the most that is advisable. Once dry, a light sanding with fine paper restores a smooth surface.
The original colour can be brought back with a proprietary wood cleaner and kept with teak oil or a sealer, reapplied once or twice a year. Oil applied over a dirty or damp surface traps mould and turns black.
Rags soaked in linseed, teak or Danish oil can ignite on their own as the oil dries. They are spread out flat outdoors to dry, or soaked in water, before being thrown away.
Pine and other softwoods rot unless protected. Furniture is checked each spring for soft, dark patches, particularly at the feet and joints where water collects. Sound timber is sanded and given a fresh coat of exterior wood stain, preservative or paint; flaking paint is taken back to a firm edge first. Small areas of rot can be cut out and filled with exterior wood filler, and standing the legs on stone or plastic feet keeps the end grain out of wet ground.
Rust is removed with a wire brush and coarse abrasive paper down to bright metal or a firm surface. A rust-inhibiting primer or rust converter goes on the same day, followed by one or two coats of exterior metal paint. Joints, undersides and the feet deserve most attention, since rust starts where water sits.
Paint on furniture made before the 1970s may contain lead. Such paint is not dry-sanded or burned off; the precautions are described under lead paint, asbestos and paint disposal.
Aluminium does not rust, though it can develop a dull or powdery surface. Washing with soapy water is usually all it needs. Chips in a powder-coated finish are touched up with matching metal paint to stop the coating lifting.
Plastic furniture is washed with warm water and washing-up liquid. Stains and the grey film left by algae respond to a paste of bicarbonate of soda or to diluted white vinegar; abrasive cleaners scratch the surface and make it hold dirt. Faded plastic can be painted with a primer and spray paint made for plastics.
Sunlight eventually makes plastic brittle. A chair with cracks in the legs or seat is unsafe and cannot be repaired. Rigid plastics are accepted at many household recycling centres.
Natural rattan, cane and willow are not weatherproof and belong indoors or in a conservatory; outdoors they are wiped clean, dried and kept under cover when not in use. Most outdoor "rattan" is a woven synthetic resin, which is washed with soapy water and a soft brush to clear dirt from the weave.
Removable covers are washed according to the label. Fixed fabric is brushed, sponged with soapy water, rinsed and dried fully in the open air. Mildew grows on fabric put away damp, so cushions and parasols are dried before being brought in.
Bolts and screws work loose as wood shrinks and swells, and are tightened each spring. Rusted fixings are replaced with stainless steel or brass. Loose glued joints are cleaned out and reglued with waterproof exterior adhesive, then clamped until set. Folding mechanisms and hinges take a drop of oil.
Furniture lasts longest in a dry shed or garage over winter. Where that is not possible, a cover made of breathable fabric keeps rain off while letting moisture escape; plastic sheeting tied tightly traps condensation and encourages mould. Raising the feet off the ground and tilting table tops so that water runs off both help.