Polyurethane is a very tough, durable varnish that coats a piece of wood with a plastic-like coating. Polyurethane is impenetrable by many substances, even those that are acidic, making it ideal for use on cabinetry. When cleaning polyurethane cabinets, remember that you're cleaning the finish, not the wood, so using cleaning products suitable for the coating is very important.
Test the Finish
Before you do any polyurethane furniture care on your cabinets, test the finish to ensure it's actually polyurethane. Other finishes mimic the polyurethane look but react differently to cleaning supplies. Rub a few drops of boiled linseed oil into the wood. If it beads up, it has a hard finish, not an oil-based one.
Rub a little acetone, found in nail polish remover, over an inconspicuous spot in a small, circular motion. Lacquer will dissolve and varnishes and shellacs will turn sticky after a few minutes. Polyurethane will repel the acetone, and it will bead up like water. If you find your cabinets have a different finish, use lacquer furniture care or other finish care to clean them.
Dust Cleaning Polyurethane Cabinets
Keep your cabinets dusted well using a dry microfiber cloth. Brush very dusty areas or built-up dust off the cabinets with a stiff, nylon brush. Brush in the grooves of the cabinet gently. Use short, gentle strokes to remove the dust.
A small toothbrush can be used to gently remove dust in crevices. A vacuum with a brush attachment can also be used to remove dust from cabinets.
Grease and Grime Removal
When cleaning anything covered in polyurethane, remember that you're cleaning the finish, not the wood. Wax and furniture polish on polyurethane cabinets can build up and become a problem later on, so minimize their use on the cabinets. A moist cloth wipes away a lot of grime, dirt and grease, but you may need to upgrade to other cleaners for stubborn grime.
Mineral spirits on a clean rag will remove most smudges and dirt. You can also use a mixture of water and vinegar in a spray bottle to remove dirt and greasy marks on your cabinets. Greasy marks can get all over a cabinet whether you're cooking or there's just a lot of use.
Vinegar breaks up the grease without damaging, causing any abrasion to the polyurethane. Because vinegar works like a glass cleaner, it also won't cloud the finish like other cleaners and can break through any buildup. Rubbing alcohol applied in small amounts to a clean, dry cloth can also be used to rub away grease and grime, especially those found around knobs.
Polyurethane Cabinet Stain Removal
One of the best ways to get rid of stains on a polyurethane cabinet is to use a microfiber sponge and rub the stain away. Permanent marker, crayon and other stains are easily removed this way.
If the stain discolors the polyurethane, sand the stained area off with a fine grit sandpaper. Wipe away the dust left behind with a tack cloth and reapply a coat of polyurethane. Let it dry, and sand and reapply if it needs it.
If the stain splatters or covers a large area, take the door off if the stain is on the door and refinish it completely to get a uniform look. If the staining is on the cabinet itself, refinish that side.
Michelle Hogan is a writer and the author of 13 books including the 2005 bestselling memoir, "Without a Net: Middle Class and Homeless (With Kids) in America." Hogan studied English at American University and has been writing professionally since 1998. Her work has appeared in "The New York Times," "Redbook," "Family Circle" and many other publications.