How to remove buildup from old wood furniture
You’ll find advice online that includes wiping off the sticky stuff with vinegar and water or using a homemade mixture of equal parts turpentine, white vinegar, and boiled linseed oil.
Jeff Jewitt, refinishing expert and author of “Refinishing Furniture Made Simple” and other refinishing books, recommends starting by putting on nitrile gloves and dampening a rag in paint thinner or mineral spirits. . Rub a small area in circles, he says, then twist the cloth to expose a clean area and move on to the next spot.
This treatment will remove oily dirt, old wax and varnish, but it will not remove water-soluble dirt, which is often a bigger problem. For this, he recommends using a capful of Dawn dish detergent in a pint of warm water.
Carol Fiedler Kawaguchi, finishing expert in Bainbridge Island, Washington, and owner of C-Saw (cfkawaguchi.com/csaw), a company that focuses on restoring antiques, typically skips the step involving paint thinner or mineral oil, and instead of Dawn uses original Murphy Oil Soap ( $4.59 for 16 ounces at Ace Hardware) diluted in lukewarm water. The label suggests using ¼ cup, or two ounces, in a gallon of water, but for a smaller job, you can mix three teaspoons of cleaner with four cups of water. For tough jobs, you can double the strength of the cleaner.
It may seem counterintuitive to clean wood furniture with a high water content cleaning solution, but remember that you are now cleaning the finish, not the bare wood. The trick, according to Jewitt and Fiedler Kawaguchi, is to avoid saturating the finish or creating puddles.
Jewitt uses a clean, damp, non-dripping cloth, and he frequently folds it over to expose clean areas. Fiedler Kawaguchi uses a well-wrung, soft scouring pad or sponge. She frequently rinses the sponge or pad in warm water, wrings it out, dips it in the cleaning solution, and wrings it out again to clean a new area.
Both Jewitt and Fiedler Kawaguchi recommend doing a light final rinse with plain water and a clean, wrung-out cloth. “The idea is to keep water rinsing to a minimum,” Fiedler Kawaguchi said. When she’s finished, she wipes the surface.
If the part is still tacky when dry, the finish itself is likely compromised and simple cleaning will not suffice.
Fiedler Kawaguchi’s next step is to determine if the finish is shellac, a natural resin created by a type of insect. Shellac is a common finish on antiques, but it’s rare on modern furniture, which is usually coated with lacquer, varnish, or polyurethane. Pour a small amount of denatured alcohol over the finish, wait a few minutes and see if the finish is sticky; if so, the finish is shellac.
If it’s shellac, Fiedler Kawaguchi puts on nitrile gloves and goes over the finish, this time with denatured alcohol on a cloth or soft scouring pad. When she’s lucky, it revives the finish enough and no further work is needed. “He can sometimes pull the grimy stuff out without taking it all off,” she said.
You can stop at any time, wait for the surface to dry, and test if it’s still gummy. Once the sticky material is removed, a new coat of shellac can be applied if needed, as fresh shellac sticks to old shellac.
If the finish isn’t shellac, switch to a solution of half denatured alcohol and half lacquer thinner, which will remove the gummy shellac. Lacquer thinner is a stronger (and more toxic) solvent than denatured alcohol, so she makes sure to have good ventilation. She uses shop towels to wipe up the residue.
If that doesn’t work, she uses Citristrip Paint and Varnish Remover Gel ($12.98 a liter at Home Depot), which removes many finishes, including paint, varnish, polyurethane, lacquer, and shellac. . Wearing nitrile gloves thick enough to withstand strippers and working where there is plenty of ventilation, she applies the stripper with a brush and waits for the finish to soften, which can take anywhere from 30 minutes to 24 hours. The surface should also be covered with plastic overnight, so that the stripper does not dry out.
She then uses a nylon scraper – never metal – to remove most of the residue. She gets the rest by using a heavy-duty 3M stripping pad ($2.98 for two at Home Depot) with a little paint thinner or turpentine, plus shop towels.
For a final rinse, she uses paint thinner or turpentine. (It avoids water, as the surface is bare wood at this point.) Once the surface is dry, which may take some time after applying paint thinner, it is ready for staining or an oil-based finish. For shellac, hairspray, or a water-based stain or finish, a final cleaning with denatured alcohol is also required to remove oily paint thinner residue.
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