When painting a woodworking project, cabinets, or wood trim, paint drips are a common problem, and they can be especially frustrating when they dry before you notice them. Paint drips are usually caused by applying too much paint to your project in a single coat, typically from an overloaded paintbrush. Gravity causes the excess paint to run, and as it begins to dry, the paint congeals in visible drips. The good news is you can fix paint drips even after the paint has dried, and it's even easier if you catch them 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 just 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 usually creates unsightly cross-strokes that are 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 already too dry, and any additional brushing will just exaggerate the problem.
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 it is still damp, the paint may 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; sanding back and forth, opposite the direction of the drip, causes the paint to gum up or flake away, leaving you with a bigger blemish. Take care to sand only the drip itself, avoiding the surrounding paint.
Once you're satisfied that the drip has been flattened fully, apply another topcoat or two of paint. Once the paint dries, 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 if 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. Let the putty dry, then sand as directed. It's a good idea to first prime the puttied area to prevent problems with the topcoat; sometimes paint will develop pinholes if it is applied directly over putty. After priming, apply another coat or two of topcoat paint to hide the repair area.