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How to remove paint from wood without damaging the finish

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Q: I had painters in my house a few weeks ago and I noticed some paint left on my dining room sideboard. This is a beautiful cherry cabinet and is part of a custom set made for me by John Landis. How do I remove it without damaging the furniture?

A: Because you know who made your piece, a quick phone call to John Landis Cabinetworks in New Jersey (215-520-9071; jlcabinet.com) was all that was needed to identify the type of finish: a Sherwin-Williams catalyzed varnish. John Landis, who designs all the parts his company makes but now has a team working on fabrication and finishing, said he also adds paste wax for extra protection over varnish on surfaces that will wear a lot, like the top. and surrounding edge on your dresser.

Paint doesn’t adhere well to catalyzed varnish and especially wax, so there’s a good chance you could scratch the paint off with a fingernail, he said. That would be especially likely if he had noticed the painting earlier. Water-based paint, which accounts for the majority of paints in use today, dries in a few hours, but takes several weeks to cure and become tough enough to withstand washing or scrubbing.

Christopher Brazie, whose LinkedIn profile identifies him as “Technical Services Specialist, (old paint fart)” for the Industrial Wood Coatings Division at Sherwin-Williams, also said that scraping paint with a fingernail is the best thing to do. you can try first. There is no risk of damaging the finish or altering its gloss, or staining the surface with paint residue, which could happen if you smooth the drip with solvent.

But since the paint is probably already cured, it may not be scratchable. Brazie said that when asked about how to remove cured paint splatters from clear wood finishes, one of her first questions is if the splatters are overspray, a bunch of little dots that fell when the paint was sprayed. paint, or paint stains that dripped or were smeared from a brush. The splashes dry quickly because they are so small, she said. The best way to remove them is to buff them with a woolen pad, like the kind used by car polishers to polish vehicles. Mounting the pad on a drill or polisher works best, because the speed removes the paint, but it’s also possible to hold it down and polish it yourself, she said.

Drops and stains from a brush take longer to dry, which means they are easier to scrape off or clean at first. But if the drips and stains heal, you may need to apply a solvent to soften the paint so you can scrape or wipe it off without damaging the finish.

Fortunately for you, using a solvent is probably less risky with conversion varnish than with other finishes. Conversion varnish, made by many companies, is a two-part finish that must be mixed in a precise ratio before spraying. Traditional lacquer finishes, used by some furniture and cabinetmakers, are one-component finishes. The conversion varnish becomes thicker, which means the applicator has to apply fewer coats. Coats are also more scratch resistant and, in most cases, more resistant to food spills or household chemicals. Brazie said conversion varnish is the best clear finish for wood furniture. β€œIt is the clearest transparent layer, and the most resistant and durable”.

Sherwin-Williams manufactures three types: Sher-Wood White Waterborne Conversion Varnish; a similarly named product that has “Kemvar LF” in its name; and Sher-Wood F3 Kemvar varnish. The LF is the code for “low formaldehyde content”. The F3 version does not contain formaldehyde.

All are sold as industrial finishes only (not like the ones you’d normally find in a home center). According to product data sheets, 22 chemicals, including foods such as lemon juice and butter, as well as solvents such as household ammonia, 50% ethyl alcohol and turpentine, have no effect on the varnish of basic conversion, which represents the majority of sales, or in the low formaldehyde version. But formaldehyde-free conversion varnish is not as durable. It is listed as resistant to only 10 liquids, the same as for Sher-Wood catalyzed lacquer (Precat). But even that list includes alcohol, specifically 100-proof alcohol, which includes whiskey.

That all three conversion varnishes and the catalyzed lacquer list alcohol as something that is unlikely to damage the finish is significant: Alcohol is often the safest way to soften and dissolve cured water-based paint, Brazie said. But the ratio of alcohol to water should not be more than 50 percent, so she suggested diluting the denatured alcohol with a quarter to a half of water. If you’re using 70 percent isopropyl alcohol, mix 7 teaspoons with at least 3 teaspoons of water.

Do not pour the diluted alcohol mixture on the wood. Instead, moisten a corner of a soft cloth and apply the solution with that. Wait a minute or two and check if the paint is soft. If not, wait a little longer. Alcohol evaporates quickly, so reapply if necessary to keep the paint wet. When the paint softens, scrape it off.

If you don’t have the advantage of knowing what kind of finish your furniture has, you could still start by trying to scratch the paint off with a fingernail. That is always safe. But before using a solvent, even one labeled for use on furniture, you’d be wise to make sure it won’t affect the finish. Try somewhere that isn’t very visible, like the inside of a leg. Apply some solvent, wait a couple of minutes, then rub with a cloth to see if any finish comes off or if the surface becomes dull. Alcohol dissolves shellac, for example.

Do you have a problem in your home? Send questions to [email protected]. Put “How To” in the subject line, tell us where you live, and try to include a photo.

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