Q: I bought some of the humidifier balls that are being promoted in many catalogs — white, porous ceramic globes that sit in bowls filled with water. Today I discovered to my horror that they both have black mold spots on them. I soaked them for several hours in hot, soapy water, but it didn’t remove the black stains. I tried scrubbing the stains with a sponge, but that didn’t work, either. What can be done?
— Luanne Johnson, Orrville
A: Detergent won’t kill mold, but chlorine bleach will. I’d try cleaning them with a solution of about one part chlorine bleach to 10 parts water. Bleach is caustic, so protect your skin and eyes and be careful not to splash the solution on your clothes or anything else you don’t want bleached.
Since the humidifier balls are porous, cleaning alone may not remove all the stains.
Try covering the moldy spots with a paper towel soaked in undiluted bleach and letting it sit overnight in a well-ventilated area. (That’s a great trick for whitening moldy bathroom grout, by the way.)
After that, I’d just keep an eye on them and clean them often to prevent more mold growth.
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