The phrase "loaded brush" means when someone is intentionally using their influence or power in a biased way to achieve a particular outcome. It implies that the person has a hidden agenda or is favoring one side unfairly. Full definition
Looking at the painting with me he explains how he achieved the rainbow stripes by loading a brush with contrasting colours and drawing it across the canvas. (patternsthatconnext.wordpress.com)
Willem de Kooning (1904 - 1907) used with loaded brushes and garish colors that seemed to collide rather than settle down into co-existence. (thoughtco.com)
Nonetheless, a shaving bowl is not all that essential, as you can always build up the lather directly on your face after loading the brush with soap. (primandprep.com)