Hand sanding should always be done with a back-and-forth motion that is parallel to the grain of the wood, not across it. Between sanding passes, the surfaces should be wiped clean with a tack cloth or clean cloth moistened with mineral spirits. This will remove sanding dust and keep the wood pores clear so that the subsequent sanding action is effective.
It is best to use sanding blocks when hand sanding, in order to keep the sandpaper in firm contact with the wood surfaces. A flat block will suffice for sanding flat expanses. You can wrap sandpaper around scraps of carpeting, dowels of different sizes, foam pipe insulators, or other makeshift objects to conform the sandpaper to various shapes matching the contours of your woodworking piece. You can also sand by folding the paper and pressing by hand. Try to avoid dulling or rounding over the edges of decorative contours when sanding.
When sanding is complete, the wood should feel silky smooth to the touch. Before moving on to staining and top-coating, make sure to wipe the wood clean again.
Before sanding end grain, run your fingers along the edge. You should notice that one direction feels smoother than the other direction. Sanding in the smooth direction will yield better results.
Sanding Between Finish Coats
Most experienced woodworkers apply two or even three coats of varnish or oil finish to a woodworking project. Between coats, the surfaces should be lightly sanded with 320- or 400-grit silicon carbide sandpaper. Wipe the surfaces clean before applying the next coat.
For the very best finishes, some woodworkers take a final step of wet-sanding the final dried topcoat with silicon-carbide wet-dry sandpaper. Use mineral spirits or water as a lubricant, and wipe the surface completely dry after finished. A final buffing with a non-woven synthetic pad will shine the surface to a uniform glossy finish.
For a truly professional look to your woodworking projects, always hand sand before moving on to staining and finishing. The effort will clearly show in the quality of your finished work.