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.
Nylon or nylon/polyester brushes are best used with latex paints and water based finishes. Keeping these tools CLEAN is the key to a great job and longevity of the tool itself. Here are some tips to help you keep your finishing brushes clean: For all brushes used with water based materials, simply wash out as much material as you can with warm water.