Polyurethane varnish is easy to apply and hard wearing, it’s available in a wide range of lustres (from matt to high gloss) and also different tints and colours.
Polyurethane stands up to handling and exposure to heat, water and alcohol (unlike wax and French Polish), which makes it ideal for tables and trays etc.
Polyurethane varnish also has the advantage that it gives a high build and is easy to apply.
Application of Polyurethane Varnish
Varnish is usually applied using a brush. The brush should be kept specifically for applying varnish (if the brush has been previously used with paint, its use with varnish can lead to contamination of the varnish). Only the best quality paint brush should be used to avoid hairs breaking off and becoming trapped in the finish.
Before applying varnish, make sure that the surface is smooth, dry and free of dust – wiping the workpiece with a cloth damped with white spirit will help remove fine dust. Avoid varnishing in a draughty, damp or dusty area so that the finish is not ruined.
When varnishing a largish area, mentally divide it up into a number of squares (see right) and apply the varnish to each area in turn until the whole area is covered (for left-handed people, reverse the horizontal numbers by starting at the top right-hand corner).
Apply the varnish in three stages:
- Load the brush with varnish and brush it on along the grain of the wood.
- Without applying any more varnish, spread it across the grain of the wood.
- Finish off by 'laying off' the varnish - i.e. using soft strokes of the brush (just the tips of the bristle) along the grain.
If you need to apply another coat, wait until the previous coat is dry and then lightly rub down the surface using a very fine sandpaper before applying the next coat.