Have you ever used a scrub brush to clean something? Using a scrub brush in conjunction with a cleaning chemical is like a one/ two punch. The scrub brush provides the mechanical action to remove the really tough dirt. If you believe the harder you press down on the brush when scrubbing the better you’ll clean you would be wrong. Brushes actually clean best when the tips are moved back and forth over the surface. If you press hard the bristles get bent down and you’re scrubbing with the sides of the bristle. Try this on your hand and you’ll see what I mean. It’s the tips of the brush that really do the work. Hope this helps more professionally.