Naturally the simplest way to get the best result will be to hire a professional painter. My guess if you’re reading this you’ve already called every painter in town no one will pick up time to take matters into your own hands..
At the shop we apply finishes inside our industrial spray booth using special catalyzed paint and many thousands of dollars’ worth of spray equipment. It’s a labor intensive and time consuming process to get a furniture-quality finish. Painting on-site or in the driveway is a different process. Professional house painters have their own tricks of the trade to get great results from the end of a brush.
I have no professional-level brush painting experience though will share what I’ve picked up over the years on painting home projects in my driveway. First thing: painting with a brush takes practice and skill. I prefer a foam mini roller as it takes a lot less skill to spread out an even coat of paint that way.
To paint our U-paint MDF shelves (or any raw wood) you’ll want to start with a stain-blocking primer. Usually 2 coats is what it will take to smooth out the surface and block the tannin from bleeding through. Its not so much the priming but more the sanding that produces the smooth surface reflected in the final coat of paint. Sand between coats with 220 paper to knock down any fuzz etc. Do not sand with spent paper. If your paper loads up with gummy spots then you’re too early. Be patient wait for it to dry nice and crisp and use fresh paper. You need to sand the primer completely smooth. If the primer isn’t sanded out smooth and lovely then the paint won’t be lovely either.
I like to use BIN pigmented shellac primer because it seals very well and dries quickly, maybe too quickly… you need to be ready to go when you dip the roller get moving keep moving keep a wet edge to the end don’t stop there is no time for repositioning have everything in place.
Cleaning and re-using rollers might sound less wasteful but in practice not so. Even a little debris in your finish is too much. So now you have to do it again anyway with a new roller to get it right. Don’t try to clean a roller. If you are going to use it again the same day or next day, get it loaded with paint then wrap it tight in a plastic bag leaving no air inside. This will keep the roller and paint fresh for a couple days. I’ve gone longer than a couple days with success on this but eventually it will dry out. Don’t wash a roller in the sink, doing so washes paint down the drain which is pollution. Some say it’s no big deal they treat the sewage.. this is false there is not a process to separate diluted liquids like paint from wastewater. The proper way is to roll the excess paint out onto a piece of scrap or cardboard etc. and then take the roller off and leave it to dry out. Once its dry put it in the garbage.. don’t put liquid paint in the garbage. Dry paint is fine to toss out.
There is more to paint than color. Quality paint will help you get a better result and offer better durability. Benjamin Moore Aura paint is a top performer, the Ben Moore regal is a little less money and quite good as well.
Stick with either matte or eggshell sheen. Higher sheen is more picky to work with and reveals more flaws. Some people say higher sheen is better suited for traffic and moisture etc. I don’t believe any of that. Lower sheen paints dry more readily and is more forgiving. If you are trying to paint shelves in your carport after work then you need as much forgiving as the day will allow. Lower sheen finishes are plenty durable/cleanable as long as you use quality paint.
Stand your shelves up on edge and lay some skinny sticks so it’s not touching the table except for the sticks that way you can coat the entire thing in one shot. You have to apply the right amount of wet paint to get a smooth finish. Too much paint will drip and run whereas not enough paint cannot flow into a smooth finish before it dries. Again, using a new foam 6″ mini roller is my preferred way to quickly paint.. go ahead splurge and use a brand new roller for your final coat.