Polyurethane varnish gives bare wood a lustrous, hard-wearing finish which is easy to clean and maintain. As well as clear varnish, a wide variety of colours and natural wood shades are available. The clear varieties come in matt or gloss and these can be mixed. Polyurethane can withstand heat without marking, though intense heat may eventually damage the wood underneath. It is important to let the polyurethane set: with some varieties it can take up to two weeks to achieve maximum hardness.
Apply the varnish directly to the sanded wood with a paintbrush. Because the varnish must be applied in coats, it is a good idea to dilute the first with white spirit so it soaks in and seals the wood. When the first coat is dry, lightly rub it down with fine glass-paper before applying the next. Subsequent coats can be diluted in the proportion of one part white spirit to three parts polyurethane to give thinner coats which will brush on more easily.
Before applying the coloured variety apply one coat of clear polyurethane to seal the wood or you may get a patchy effect. For a matt finish, apply a final coat of clear, matt polyurethane after the coloured coats.
Finishing – with wax polish
Wax polish can either be used in conjunction with polyurethane, or by itself as an alternative finish. Although wax gives a warm, mellow look to the wood, it has hardly any resistance to heat and marks easily – so its use should be confined to more decorative furniture.
With polyurethane, use a proprietary, white wax polish. After the final coat of varnish has dried, rub over it lightly with a very fine (0000) grade of wire wool. Having brushed away the dust, rub in the polish with a coarse rag to give an even, matt sheen.
Finally, buff up the surface with a fine cloth. Successive layers of polish, built up at the rate of one every two days, will deepen and harden the finish.
For a pure wax finish, you can make up your own beeswax polish. For this you need pure beeswax – available from hardware shops – turps substitute and a glass jar.
Grate the beeswax with a cheese grater and put it in a jam jar. Pour in just enough turps to cover the wax.
Stand the jar in a pan of very hot water and stir until the mixture melts and forms a thick paste – on no account expose the jar to a naked flame as the turps substitute is highly inflammable.
Dip a clean rag in the wax and rub the mixture into the clean wood surface, taking care to spread the wax evenly. Apply enough wax to soak in to the grain but avoid leaving any proud of the surface.
When the wax has hardened completely – in about an hour – buff up the surface with a fine cloth.