Mold spores establish colonies and spread rapidly in locations where moisture isn't able to dry completely. Bathrooms and kitchens often attract mould colonies, which may give off a telltale musty odour and appear on walls, ceilings and other surfaces as a white or green powdery substance. Bleach won't completely kill mould, but is a good pre-cleanser for mouldy walls and ceilings. To kill mould colonies, use borax or borate dissolved in water. Many detergents, especially those designed for automatic dishwashers, contain borate.
Don protective eyegear, gloves and mask. Inhaling mould spores can make breathing more difficult for people who suffer from asthma or other respiratory illnesses.
Remove all items and furnishings from the area you're about to clean. If you detect or suspect any mould on them, close them up tightly in plastic trash bags to prevent mould spores from spreading to other areas of your home.
Dissolve 1 cup of washing powder in a gallon of warm water. Working in small sections, wash the walls and ceilings with the mixture. Scrub stains to help remove deep-ground mould.
Allow surfaces to dry. Use fans and open windows to speed the drying process.
Add 3 tbsp of bleach to a quart-sized spray bottle. Fill the bottle with warm water. Spray the mixture on mould spots, working top to bottom, left to right. For large areas, dissolve ¼ cup bleach in a gallon pail of warm water and apply with clean rags.
Wait for the walls and ceilings to dry completely. Dissolve 1 cup of borate-based detergent in a gallon of warm water.
Apply the solution to the walls and ceilings with clean rags. Allow the area to air dry, using fans and open windows to quicken the process.
Sweep and wash floors, counters, appliances and other surfaces with the borate solution before returning moved items to the room. Be sure all surfaces and items are mould-free, or mould colonies may return.
Use a dehumidifier to keep moisture-prone areas dry.
Don't allow people to move in and out of the room while you're cleaning away mould. They can easily carry mould spores from one place to another. Attack new mould colonies as soon as they form to keep mould from spreading.