Mildew is a type of mould that discolours surfaces with black patches and gives off a musty smell. It thrives in warm, dark, damp environments. Mildew can build up in camper vans that didn't dry properly prior to closing up, or in campers in damp climates that have been covered and closed for long periods. Effectively cleaning bad mildew stains involves not only removing the stains, but killing the mould and preventing it from recurring.
Open up the camper van to dry in the sun. Open any pop-up canvas sections and all of the doors and windows. Remove any mildewed mattresses or cushions and set them out in the sun.
Remove the covers from cushions, pillows and mattresses. Clean the mildew out of them with a vacuum cleaner.
Spray them with a solution of 59 ml (1/4 cup) of bleach mixed with 4.5 litres (1 gallon) of water (test a hidden part of an unremovable cover to make sure it is colour-fast with the bleach solution before spraying). Let the bleach sit on the surface for several minutes. Then scrub the stains with a brush. Leave the cushions and mattresses to dry completely in the sun.
Wash any other stained fabrics and cushion covers in washing powder and very hot water. Leave them in the sun to dry.
Remove interior mildew just as you would clean it in your house. Use a 50/50 bleach and water and a soft cloth or brush to scrub mildew from sinks, showers and any stained wood and vinyl surfaces. Rinse well.
Check the manufacturer's instructions before applying any cleaner to canvas parts of a camper. The canvas is usually treated with a waterproofing material that you don't want to strip away.
Wet the interior of any pop-up canvas with clean water. Scrub the canvas thoroughly with hot water and washing up liquid to remove as many of the stains as you can.
Wash the inside of the canvas with the 50/50 bleach solution, unless otherwise specified by the manufacturer. Let the bleach sit on the canvas for several minutes. Then rinse the canvas with clean water and a cloth.
Wipe all interior surfaces dry with a soft cloth.
Close all the camper's doors and windows before cleaning any exterior canvas pop-up parts or awnings. Spray the canvas all over with a hose, and clean the exterior canvas as described in Steps 7 and 8. Rinse with the hose.
Spray any remaining exterior mildew off the camper with the hose. Clean stubborn mildew stains with the 50/50 bleach solution and a cloth or brush.
Leave the camper open in the sun to dry completely. Open all the doors and windows, as well as any awnings and pop-up sections.
Open your camper at least once a month to air it out and to check for any mildew build-up. An open box of bicarbonate of soda placed in any closed areas like showers or cupboards can help prevent future mildew.
Very badly stained canvas that resists this treatment may have to be replaced.