How To: Deal with mildew on honeycomb shades

Q. In my bedroom, I have 10-year-old vinyl replacement windows that I keep covered with heavy-duty, top-down-bottom-up honeycomb shades. In the winter, when I open the shades in the morning, there is a lot of condensation on the windows, and I have noticed black mildew on the windows near the bottom and on the back of the shades. I have used 100 percent vinegar, a diluted bleach solution, and a commercial sodium carbonate spray, but none of these has eliminated the mildew. Are we in danger? What should I do?

Columbia

A. There are two issues here: health and appearances. Mildew on shades is clearly unsightly, but if there is just a tiny amount, it’s not likely to be a health issue if the overall air quality in your home is fine. However, the mildew could also be a sign of excessive humidity, which can lead to an overall musty environment. That is more serious.

To figure out the scale of your problem, buy a humidity sensor, also known as a hygrometer, for $10 to $20 at a hardware store. If the relative humidity is above 70 percent in the bedroom (or other rooms, although obviously not the bathroom immediately after a shower!), you need to take steps to get the reading down, ideally below 60 percent. If the reading is high only in the bedroom at night, try leaving the door open. A sleeping person expires a lot of moisture during the night, and it condenses on the cold glass, creating an ideal situation for mildew to grow. Opening the door allows some of the moisture to move on to other rooms.

If the humidity is high throughout your house, try running bathroom fans longer or replacing them with ones that are more efficient, opening a window for a while each day unless it is more humid outside, and using an exhaust fan in the kitchen when you are cooking and washing dishes. If these don’t bring down the reading enough, try running a dehumidifier.

In addition, you might want to check for drafts and seal any gaps you find around the window where the mildew is showing up. Opening the shades during the day, which it sounds like you’re doing, also helps dry out the surfaces and keep mildew from growing. Opening blinds only at the top isn’t a good strategy when mildew is a problem because keeping the bottom enclosed reduces air circulation in the coldest area, where condensation and therefore mildew is most likely.

As to cleaning up the mildew, the spores are just as likely to make someone sick whether they are dead or alive. So removing the mildew by wiping it away is important from a health standpoint. But dousing the stains with bleach or other products is more of a cosmetic issue. Focusing on “killing” the mildew is pointless, because plenty of live mildew spores are always wafting about.

As to how to remove the stains in the blinds, call the manufacturer. Or call one of the well-known makers of blinds similar to yours and ask for cleaners in your area that they recommend. (The Hunter Douglas referral number is 888-501-8364.) Professional cleaners of window coverings have several effective methods that work on honeycomb shades, including injection-extraction and ultrasonic cleaning, coupled with spot treatment of especially stubborn stains. It might not be possible to remove the mildew stains entirely, however.

I need to have a pad made for a window seat. The space is quite large (921 / 2 inches long by 22 inches deep). Having two cushions side by side would be acceptable. Do you have a suggestion for someone who can make this for me?

Woodbridge

This is the kind of job that any upholstery shop should be set up to do. Two in Woodbridge are Nelson’s Upholstery (703-590-7271, www.nelsonupholstery.com) and Prince William Upholstery (703-496-4335, www.princewilliamupholstery.com).

It’s no problem to order a single long cushion. Or you can have two or even three smaller ones, though the price might be higher because there are more sides to sew and zippers to install.

Prices vary a lot, depending on the foam and fabric you select, and also on whether you want corded seams. When a cushion will be used a lot, thicker, more dense foam makes sense, as do corded seams, because these wear better than plain seams. If the cushion will be mostly for show, you could skimp on these.

Upholstery shops usually carry fabric or have sample books that you can peruse and order from, but prices tend to start at about $25 to $30 a yard, so people often shop at fabric stores or order online. Be sure to pin down design details, such as foam thickness and whether you want cording, before you buy because those affect the yardage.

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Send home-improvement questions to localliving@washpost.com . Please put “How To” in the subject line, tell us where you live and try to include a photo.

 
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