Choose a varnish that is specifically made for salad bowls to ensure the varnish does not contain chemicals that will be harmful when working with food. This varnish comes in a variety of colors.
Sand the cutting board on all sides to create a slightly roughened surface. Wipe the board with the dry cheesecloth to remove the dust created from sanding.
Add equal parts water to the salad bowl finish and apply the mixture to a small area of the test wood to see how fast it is absorbed. If it is not absorbed immediately add more water to the mixture 1/4-cup at a time and continue testing until it is absorbed immediately.
Lay some newspaper on a flat working surface. Lay the cutting board on top of the newspaper. Use the cheesecloth to apply the mixture of varnish and water directly to the top of the cutting board until it begins to seep out of the bottom of the board. Set the board on a vertical side to dry overnight.
Sand the cutting board lightly and reapply the mixture until it seeps out the bottom. Set it on its side to dry overnight again. Repeat this process again until the finish doesn't absorb. Wipe the cutting board with a clean cloth.