Brush Marks from a Poor Paint Job
DEAR TIM: My son was visiting me and decided to do a good deed. With the help of my wife, he painted our front door. The color is a magnificent bright red but the finish has many brush strokes. Up close, the door looks horrible. What is the best way to refinish the door? Can I simply sand the high spots or must I strip the paint from the door? My son and wife used a disposable brush. Was that the problem? How can I avoid brush strokes in a newly painted finish? Renard I., Rochester, NY
DEAR RENARD: Ugh! I have seen my fair share of painted surfaces that look good except for the defect you describe. Other defects such as unfilled holes, unsanded peeling-paint edges, uncaulked cracks, etc. can also ruin an otherwise great paint job. Professional painters and those that sell paint sundry items constantly preach the mantra of using the best tools when painting, as well as doing all necessary preparation before paint is applied. Your wife and son had the best of intentions, but possibly underestimated the required steps to achieve professional results.
The actual technique of applying the paint may not have been a problem. It is entirely possible that the previous coat of paint had the ugly brush marks and this new coat of paint could not hide them. Certain paints have more body to them and some can hide subtle surface defects by bridging over them. Even if such a paint was used, I would never depend upon it to cure an obvious surface defect. If the previous painter created the problem, the surface should have been sanded to remove the brush marks.
At this point the best thing to do is to wait until the new paint hardens enough so that it can be sanded. This curing process can take anywhere from 10 to 30 days. In certain situations it may take longer than 30 days. If you try to sand uncured paint, it will rapidly clog the sandpaper. Attempting to sand a paint finish less than five days old can lead to disastrous results as the film can actually tear apart. If you are so impatient that you can't wait, then chemical stripping is the path you must take. Personally, I would only strip the door as a last resort. Paint stripping can be a messy task to say the very least.
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I would start sanding using a hand-held power sander that has an orbital sanding pattern. These power sanders do an excellent job of removing surface defects when equipped with the right paper. Try using 120 grit aluminum oxide sandpaper for the first sanding. Aluminum oxide is the light brown sandpaper you see at paint stores or home centers. It is self-sharpening and affordable. You will know the paint is hard enough to sand if the sander begins to produce dust from the paint film. If you don't see any dust and the paper has started to clog with paint, I would stop and try to sand again in five to seven days.
Once you are able to successfully sand, the surface of the door should be very smooth to the touch after you run the sander over it several times. Before you begin to sand the offensive brush strokes, run your hand across them. You should be able to feel the uneven surface unless you have very thick calluses on your fingertips. After sanding with 120 grit paper, you should be able to instantly feel a much smoother surface. Do not hesitate to change the sandpaper on a frequent basis. Fresh paper cuts faster.
Once the door surface is smooth and dust-free, it is time to repaint. If you desire as smooth a finish as possible, I would absolutely remove the door from its hinges and paint the door while it is laying flat on two sawhorses or portable work stands. Be sure to use the most expensive brush you can buy and match it to the type of finish paint you choose to use. China bristle is often preferred for oil paint and a polyester brush is usually the weapon of choice for latex based paints. A professional grade brush will yield incredible results.
I would also consider using a flow extender additive to the paint unless the paint manufacturer specifically tells you it will void the paint warranty. Flow extenders tend to reduce the surface tension of the paint allowing the paint to spread out evenly under the force of gravity. By painting the door while it is flat, you essentially eliminate the possibility of runs in the paint. Once the paint is dry, you can put it back on the hinges making sure to remove any weatherstripping from the door jamb. If the uncured paint touches the weatherstripping, it can peel away from the door the next time you open it.