Living organisms require specific conditions in order to thrive, and mildew is no exception. This fungus grows in damp, warm conditions with a propensity to cling to dirty surfaces. When Roman shades hung in a room with a high humidity level become dusty or dirty, they turn into a prime location for the growth of mildew spores. To prevent damage to the shades the mildew must be carefully removed from the surface.
Lay a plastic dropcloth outdoors in a sunny location. When this is not possible, place the dropcloth in a dry room that gets a few hours of direct sunlight.
Remove the Roman shades from the window and lay them on the plastic dropcloth. Allow the shades to sit in the sun for a few hours to kill the mildew spores. Vacuum the shades, using an upholstery attachment, to remove spores on the surface.
Place rubber gloves on your hands to protect you from coming in direct contact with mildew spores. Combine 1 cup rubbing alcohol and 1 cup warm water in a bucket. Make a larger one-to-one ratio of solution if you have several shades to clean.
Dip a clean sponge in the diluted rubbing alcohol solution. Wring out the sponge so it's as dry as possible. Gently blot the Roman shades to kill mildew, ensuring that you get in between each bend and groove of the shades.
Press a clean cloth into the Roman shades to remove excess moisture. Allow the shades to dry on a clean dropcloth before hanging them in the window.
Use a dehumidifier in rooms prone to dampness. Spray your shades with disinfectant spray once or twice a month to prevent the return of mildew. Keep your shades free of dust and dirt by vacuuming regularly with the upholstery attachment. Mildew is more likely to grow on a dirty surface.