dependent for existence, occurrence, character, etc., on something not yet certain; conditional (often followed by on or upon): Our plans are contingent on the weather. 2. liable to happen or not; uncertain; possible: They had to plan for contingent expenses.
But they don't do a worse job, either. Sure, expensive bristle brushes allow you to spread the varnish out smoothly, but so does a forty nine cent foam brush. So it makes sense to use the lowest-tech, least expensive tool to do the job.
Sand the surface of the wood with 50-grit sandpaper. Use soft, slow strokes to remove the old varnish. Follow the grain of the wood and contours of any decorative elements. Repeat the process with 120-grit sandpaper and 220-grit sandpaper until the varnish is removed and the surface of the wood is smooth and clean.