The Smoothest Finish
Paint rollers are made for different surfaces and finishes. There are dozens of different rollers to choose from today. When selecting a roller remember, the longer the nap the better it is for a rough surface. Also the longer nap means you will be able to apply paint to your surface more quickly. The shorter the nap the smoother the application. So if your goal is a smooth surface, use a shorter nap and take your time applying the paint.
Three of the smoothest finishes are the Flockfoam, Microfiber and a Mohair Blend rollers. The Flockfoam roller is great for varnishes and urethanes, yet not so great for paint. Microfiber rollers work well on a rough surface. This roller however is an excellent roller to apply a smooth metallic finish to your wall.
My favorite is the Mohair blend — it works great with all paints and gives the smoothest finish. For instance, use this roller for the smoothest finish on a wood door.