Guide to Polyurethane Finishes

Antique Finishes - Lacquer - Oil Finishes - Painted Finishes - Polyurethane - Shellac - Varnish

Polyurethanes are liquid plastic resins that dry to a durable satin or gloss finish. Polyurethane finishes are much more resistant to moisture and spills and moderate heat than traditional varnishes, and do not need much protection. Most manufactured furniture is not polyurethane coated, as it requires considerably more drying time and intercoat work to apply commercially.

Dust regularly with a soft dry cloth and wipe dry. When needed, wipe with a moist cloth, not wet. This will remove fingerprints and light soil. When dirt or grime have built up, clean with mineral spirits.

Wax or polish can build into an enemy. Remove it with a cloth dampened with mineral spirits. Clean small areas at a time. Wipe each area with a clean cloth before going on to the next. Wear rubber gloves to protect your hands, and dispose of them afterward, or wash in hot suds and air dry. Air-dry cloths used in cleaning to evaporate the solvent before disposing.

Test for Existing Finish on Furniture

• Rub a Few Drops of Boiled Linseed Oil Into the Wood - If it absorbs, the wood has an oil finish. If it beads up, the wood has a hard finish (continue).
• Rub Acetone Over a Spot in a Gentle, Circular Motion - Polyurethane finishes shed acetone like water. Lacquer dissolves in 30 seconds with rubbing. Varnishes and shellacs turn to a sticky, gel-like substance after a minute or two (continue).
• Try a Few Drops of Denatured Alcohol - Shellac dissolves quickly in denatured alcohol. Varnish reacts slowly.

Antique Finishes - Lacquer - Oil Finishes - Painted Finishes - Polyurethane - Shellac - Varnish

This article has been contributed in part by Michigan State University Extension