Cutting boards are useful tools to have in your kitchen. Instead of buying one at a story you can make one yourself. Here are a few things to consider.
Sandpaper is graded as medium, or numbers 60, 80, and 100. Fine sandpaper numbers are 150 and 180, and very fine is graded 220, 240, and 280. Medium is usually used for the first sanding, fine for smoother results and very fine for smoothing finishes between coats. Sandpaper can be used wet for some finishes.
Do you want a clear finish or do you want a stain the cutting board to blend with the other pieces in your home? Do you prefer high gloss or satin?
Do you want the wood to be smooth and slick or do you want to feel the wood's grain?
Durability and Protection
How is this piece going to be used, and what are you going to set on it? Do you need minimum protection from watermarks and scratches?
Ease of Application
How do you want to apply the finish? Will you be using a rag, brush, or spray? A helpful hint is to visit an unfinished furniture store and talk to them about your needs. Look at their finishes and don't hesitate to bring a table leaf with you if you are trying to match a finish. Try a finish you might want to use on a scrap piece of wood that has been smoothed down to your project's finish. You can save a lot of heartache by taking this time to check before applying a finish that doesn't work.
You can fill in nail holes with wood putty/dough before sanding if you are not planning to stain the wood. If you are staining, fill the holes after the stain is applied. In either case, match the wood putty closely in color to the stock or use sawdust and wood glue to make your own putty.
Step 1 - Sand
Sand with a fine, wet sandpaper (start with a 120 grit on plywood and 60-80 grit on other lumber) wrapped around a felt pad or use a pad or orbital sander. Use aluminum oxide sandpaper because its grit material lasts longer.
Step 2 - Vacuum
Vacuum frequently to remove dust. Finish manufacturers recommend which grit of sandpaper to use with their specific finishes to achieve the smoothest result. Feel the wood to check on the smoothness as you work because touch is really the only way to get a smooth surface. Make sure that you remove all dust, finger marks, and excess glue before applying the finish. Vacuum or brush the entire piece clean and then wipe with a tack cloth.
Step 3 - Use Sealer
An optional step here would be to use a sanding sealer, which seals the wood so the stain goes on even.
Step 4 - Use Polyurethane
When it is time to finish and polyurethane is your choice, vacuum the room and let the remaining dust settle for 24 hours. Wear lint-free clothes and use the fastest drying polyurethane available. Use a tack rag to remove dust before applying polyurethane and between coats, after you sand. Do not apply polyurethane over a coat of shellac or lacquer. A polyurethane finish is recommended as it is highly water-resistant and bathroom racks may have a lot of water splashed on them.
If you are using a brush position the piece in horizontal sections then apply the paint, varnish or stain across the grain. Brush out the paint with the grain, using the brush as a wiping tool. Clean the brush as it collects liquid.
Pull the brush across the unit's surface with the bristles held almost vertically. Let each side dry between coats.
Step 5 - Decide on Stain
Check the varnish to see if a certain stain is called for. Read the label for drying times and how many coats to apply. Apply two, preferably three coats of urethane varnish using a good quality natural bristle brush. Between coats, wet sand the finish. Rub the surface until it feels smooth. Wipe off any residue and then apply the next coat. To get the best finish, rub with fine pumice or mineral oil.
Apply your finish in a well-ventilated space with lots of room. Cover the floor in the area that you will be applying the finish so that if a spill occurs it will not leave a permanent stain. Follow the manufacturer's instructions. The finish is the first thing you and your friends will notice, so take your time.