Preparation is a huge part of finishing. Failing to prepare the wood will surely lead to a bad finish no matter how good your equipment or coating. Let’s talk first about sanding. You must start with a completely dry piece of wood. If you have stripped it, let it dry thoroughly, this could take a few days if the humidity is higher. Then give the wood a light sanding. We suggest 180-grit sandpaper, but no more than 220. Anything finer will affect the woods ability to absorb the stain, especially on closed-grain woods such as maple and cherry. Anything coarser than that will leave visible scratches that will show up in your finish. Even if you don’t plan on using a stain, you want a little scratch pattern on the surface to promote the adhesion of your sealer or finish coats.
If you plan to use a stain, do a small color test on the bottom of a chair, inside of a drawer or bottom of table top, allow the stain to dry for an hour, if it is a water based, or overnight if it is oil-based. Then apply a little of the topcoat to make sure it has the proper sheen.