Regardless of whether you are working with softwood or hardwood the initial treatment of the wood surface contributes a lot to its longevity. Properly seasoned, dry and new wood is preferable to wet, inadequately seasoned and deteriorated wood.
The steps from start to finish may take a few stages depending on the number of coating layers you decide to apply, surface area, drying times (indoors and outdoors) etc so it might be a good idea to set aside a few days to make sure you get the job done right first time around. Ideally you want to sand down old or rough wood surfaces and use wood filler to fill in dents and holes.
Almost all types of wood surfaces require some sort of base coat or primer. Primer promotes the adherence of subsequent paint layers to the wood. This protects both the paint layers and the surface being painted resulting in an overall longer lifespan of the paint job. Correct preparation and choice of primer is essential, particularly on exterior surfaces, since different types of wood absorb moisture to a greater or lesser extent than others. New woodwork should be primed before leaving the workshop if it will be exposed to the weather.
New primed woodwork should not be left exposed to the weather for any length of time, as one coat of primer is not sufficient protection against moisture penetration. Interior woodwork, particularly in new unheated premises, should be primed without undue delay. Surfaces in permanent contact with brick, stone, plaster, etc. (e.g. door and window frame edges), should be primed before the woodwork is fixed. A second coat of paint is advisable on such surfaces, especially on end grain, to give added protection against moisture penetration.
Wood preservatives previously applied to woodwork to combat rot, mould and insect attack, can cause such problems as bleeding, loss of gloss, poor drying, and more when the wood is painted. When surfaces of this kind are to be painted it is best to get the advice of a professional paint supplier.
Softwoods, commonly used for interior and exterior work (e.g. doors, architraves, windows, skirtings, barge boards, fencing and claddings), are often porous and have varying degrees of expansion and contraction when subjected to temperature and moisture changes.
On exterior work, the paint system must be sufficiently elastic to allow for the natural movement of the wood, and at the same time provide a good water resistant and weathering surface. Gloss or similar oil paints must be used as the finish.
Interior softwood surfaces are not subject to the same rigorous conditions and most decorative paints can be employed. In conditions of high humidity and condensation use synthetic gloss, eggshell, or ready-mixed oil paints.
Hardwoods are less porous and do not expand and contract to the same extent. As they are more expensive than softwoods their use is normally confined to sills, ledges, etc., or parts where a clear finish is required. Certain hardwoods, such as teak, have a natural oiliness which can affect paint adhesion unless the oil is removed from the surface immediately prior to painting.
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