Varnish provides strong protection for wooden furniture. It provides a clear protective topcoat for furniture that goes on over stain, if desired. According to Lowe's, the main downside to varnish is that the furniture can start absorbing moisture if the topcoat of varnish cracks. Wood table owners can apply a topcoat of varnish with relative ease with just a few simple supplies and steps.
Prepare the wood for finishing by smoothing it with sandpaper. Lowe's recommends sanding any rough spots on the furniture with 120 grit sandpaper and then sanding the entire piece with 220 grit sandpaper to smooth it.
Apply any wood filler, sealers or stains before applying varnish. Apply a wood filler to the table with a putty knife to fill in any open wood grain or fill in any scratches, if desired. Lowe's recommends applying a sealer before staining a piece of furniture to help the stain go on evenly. Individuals who want to change the colour of the table need to do so with a stain before applying varnish.
Choose a type of varnish for the table. Local home improvement stores and online stores sell a variety of varnishes. Keep in mind that varnishes come with different levels of glossiness and that different types of varnishes are made out of different chemicals. A study done at Gazi University determined that synthetic and polyurethane varnishes provide more scratch resistance than cellulosic (plant cellulose-derived) or water-based varnishes. However, synthetic varnishes may cost more and emit more unhealthy fumes when wet than water-based or cellulosic varnishes.
Paint the varnish on the table. In general, most types of varnish are simply painted onto the furniture with a paintbrush. Spraying the varnish onto the table may also be an option. However, check the instructions that come with the specific type of varnish being used for any special directions. The Gazi University study also found that three coats of varnish provided significantly more scratch resistance than just one coat of varnish, so consider applying more than one layer. Allow the varnish to dry completely before painting each additional layer.
If an old table already has a layer of scratched or cracked varnish, a new coat of varnish may help repair the table, according to Utah State University. To touch up an old coat of varnish, rub the entire table with paint thinner to remove any polishes, dirt and waxes, allow the table to dry thoroughly and then repaint it with a new layer of varnish.
Varnishes often have strong unhealthy fumes and are very toxic when ingested. Therefore, use them in well-ventilated areas and keep them away from young children who may accidentally eat them.