When painting a woodworking project, one of the most frustrating problems that can occur is when you have a paint drip that you don't catch in time to fix. Paint drips are usually caused by applying too much paint to your project at one time, typically from an overloaded paint brush. The good news is, you can fix paint drips even after the paint has dried, but of course it's easier while the paint is still wet.
If the Paint Is Still Wet
If you catch the dripping paint while the paint is still relatively wet, you can probably brush out the drip. The trick is to make the brush strokes in the same direction that you used for the surrounding area. Don't try to knock down the drip by brushing in the opposite direction, as this will likely create unsightly cross-strokes that will be equally difficult to remove. Try a few brush strokes and see what happens: if this has little effect on the drip or if the paint feels tacky, stop brushing; the paint is too dry and any additional brushing may cause more of a problem than if you had left it alone.
If the Paint Has Dried
Often it's best to let a paint drip (and the surrounding area) dry completely before trying to remedy the problem. It's important to let the paint dry completely before tackling the drip. If you don't the paint can peel up when you try to scrape or sand it.
A paint drip creates a raised area that is highlighted by the paint's shininess. Therefore, the first step is to cut down or sand the raised area. Start by lightly scraping down the drip with a clean scraper, razor blade, or 5-in-1 tool. The less you can disturb the surrounding area the better.
After you've removed the raised portion of the drip, try sanding out the remaining blemish with 220-grit sandpaper.
Sand only in the direction of the drip. If you try to sand back and forth, the paint will tend to gum up or flake away, and you'll have a bigger blemish. Take care to sand only the drip, avoiding the surrounding paint.
Once you're satisfied that the drip has been addressed as best you can apply another topcoat or two of paint, and the blemish should be barely noticeable.
A More Extreme Fix
If you've scraped and sanded and there's a recessed area where the drip was, or there's any other damage due to your repair efforts, you can fill the area with a glazing putty, such as Bondo. Spread on the putty with a putty knife, then scrape off the excess with a small drywall knife or taping knife. Let the putty dry, then sand as directed. It's a good idea to prime the puttied area to prevent problems with the topcoat; sometimes paint can end up with pinholes if it is applied directly over putty without primer.