Clean the countertop thoroughly, removing any dirt, oil or food residue.
Sand the countertop with 80-grit sandpaper on the belt sander. Always sand with the grain. Wipe the counter thoroughly with a soft cotton cloth--not a tack cloth--to remove the sanding dust.
Sand the countertop with 120-grit paper on the belt sander. Wipe down the counter again. Finish by sanding the butcher block with a 150- to 180-grit sandpaper. Wipe the counter again, ensuring there is no sawdust anywhere on the counter.
Dip the brush into the stain. Apply the stain to the countertop with a steady hand in long strokes. Start from the top and side edge and bring the brush toward you. Brush back and forth to even the stain. Dip the brush again and brush the stain alongside the first strokes. Do not let the edge of the stain dry before you add another stroke.
Let the stain dry, then carefully and lightly sand with the grain again with 180-grit sandpaper. Wipe clean.
Repeat the staining and sanding until you've reached the desired color. The stain may turn darker when it's completely dry.