Happy Maintenance Monday! Here is a tip to keep your Blinds and window sills in great shape!: Do not leave windows open during rainy weather. The moisture or water spots will create a permanent stain, and may damage windowsills and walls. Blinds can be wiped clean with a warm, damp, sudsy cloth. Rinse and wipe dry. Avoid gritty or harsh cleansers, as they will damage the finish.