The causes of moldy build-up in front-loading washing machines may be water around the rubber door gasket, detergent accumulation in certain parts of the washer and leftover grime. Mold thrives in areas that are moist or not allowed to dry completely.
Front-loading washers tend to be more susceptible to mold growth because some machine parts do not dry completely after a wash. These types of washers also use less water than other washers; therefore, substances not completely washed away by water such as powder detergent, fabric softener and debris from clothes can settle in parts such as the detergent dispenser and around the door gasket. These substances accumulate and keep these areas damp, which becomes ideal for mold growth.
Some suggestions to prevent mold growth in front-loading washers include removing damp clothes from the washer immediately after washing, using liquid instead of powder detergent, putting in dryer sheets instead of using fabric softener in the wash cycle, using less detergent than recommended and cleaning the washer periodically according to manufacturer specifications.