One must always prepare the wood before applying the finish. Imperfections will only be highlighted by the finishing product. Rub down the wood with a 120 grade sandpaper and give a final sand with grade 180 or steel wool working in the direction of the wood grain.
The most common products for protecting wood are oil or water based varnishes, Danish or teak oil and wax. Varnishes are generally resistant to heat and water but read the product information for more information. Wax and teak oil offer a quicker finish/work time but do not offer the same level of protection. Always ventilate your work area and do not smoke near any polyurethane based products. Superior varnishes are often solvent based although there has been great improvements in water based products over the last ten years. Varnishes come in gloss, satin and matt. Discuss with your paint supplier what quantities will be needed for the job. Varnishes can be bought clear or with an added stain. You can always add stain yourself but do not mix oil and water based products. Wood stain will penetrate the wood while varnish will simply sit on top of the wood. I would advise that you follow the required drying time recommendations.
When applying the varnish use a brush and make confident long strokes. Between coats lightly rub down the wood and wipe the surface clean with a dry cloth before re-applying the next coat. Wood which is to be close to water, such as a kitchen, will definitely require a third coat of the varnish.
Danish oil has a faster drying time. Apply with a brush or a cloth – at least three coats. When the first coat begins to dry, wipe the wood surface with a cloth evenly spreading any surplus oil. When fully dry, lightly re-sand and apply the second coat and again wipe the wood with a clean cloth to spread the oil. Apply a third coat if necessary.
Wax works best on hard and dark woods and will require frequent further applications to build up depth and a resistant surface. When using wax begin with a coat of Danish oil and then apply the wax. After you have rubbed down the work surface apply a generous amount of wax using a lint free cloth. Rub the wax onto and then into the surface and leave for several hours. Now use a stiff brush to buff the wax in the direction of the grain. The next step is to wrap a clean cloth around the brush to give the surface a final buffing.
Teak oil is generally used for teak. This product will leave a matt finish. Apply the coats in the same way as you would for Danish oil.
As with most varnishes, oils and wax, further applications are recommended generally on an annual basis to protect the wood from strong light and water. When re-applying finishes use a furniture restorer product. Apply with a clean cloth rubbing the wood gently which will dissolve the old finish and can then be easily wiped off. A fresh finishing product can then be re-applied.