Wooden stairs can get worn down over time and lose their original smoothness. Stairs that have become rough present the danger of splinters when walking on them barefoot. For this reason, it is important to smooth down stairs before they become too rough or dangerous. Sanding down stairs is a fairly easy process, although it is a bit time-consuming to sand down every stair, depending how big the flight of stairs is. After you are done sanding the stairs, apply a wood sealant or stain, which will protect the stairs in the future.
Sweep dirt and debris off the stairs, then vacuum the stairs thoroughly.
Load the 50-grit sandpaper into the belt sander and sand each step, making sure to sand in the direction of the grain. Sanding against the grain of the wood can scratch the stairs.
Vacuum up all the accumulated dust. Load the 100-grit sandpaper in the belt sander and sand the stairs again. The 100-grit sandpaper is finer and will give the wood a nice, smooth feel.
Vacuum up all dust and debris and wipe down with a damp cloth. Apply a sealant or wood stain, if desired.