Fountain pens: flush the nib with plain lukewarm water whenever you change ink, and every four to six weeks in regular use — never hot water, detergent or solvent on the nib unit. Brass and copper: uncoated metal darkens where your hands touch it; wipe with a dry soft cloth to keep the patina, or polish back with a little brass polish kept away from nibs, lacquer and inlay. Lacquered pieces should only ever be wiped. Rollerballs write best stored capped, tip-down or horizontal. Keep pens out of direct sunlight, in their case or a pen roll.