How to Remove Mildew From a Silicone Caulk

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You can solve your mildew problem.
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Where water tries to seep into vulnerable areas, a slim line of silicone caulk protects joints and cracks in the bathroom and kitchen, where moisture can build and create a problem. It also provides a surface that is ideal for bacteria to flourish when not properly cared for.

The silicone caulking that lines the bathtub or sink can become peppered with dark spots or splotches and emit unwanted odors that bring down the overall aesthetic of the living space. If mildew has already moved into the sleek surface of the silicone caulk, then removing it sooner rather than later can keep you from having to strip the caulk and completely replace it.

When Mold Is a Problem

Mildew is the first sign of mold and can bloom into a problem if not cleaned well. Mildew gives off the same strong and unpleasant odor as mold and can weaken the caulking and structure in and around the tile if left unchecked. The pungent odor of mildew may show up before the physical signs, according to Bob Vila.

In the bathroom, mildew begins to form on silicone caulk when the area isn't well ventilated or if water is allowed to stagnate on the surfaces. Dry off the shower or sink after each use to cut down on moisture.

Mildew or mold that is contained in an area of less than 10 square feet can typically be cleaned with household cleaners, according to Today's Homeowner. If mold is climbing up the walls and hiding behind panels, then you may need to call a professional to clean the area.

Natural Cleaners to Remove Mildew

The silicone caulking will respond well to basic natural cleaners, such as vinegar and baking soda, which deodorize and sanitize. Together, vinegar and baking soda make an effective and affordable cleaning solution. They are strong enough to take out mildew that has set in and mild enough to be used regularly and not hurt the integrity of the silicone caulking.

To quickly take out mildew, use straight vinegar rather than a diluted solution. Spray the vinegar onto the silicone caulking and let it sit for at least five minutes and up to an hour. If the mildew isn't completely removed, repeat the process.

For stubborn mildew stains, sprinkle the area with baking soda and spray the vinegar onto the caulking. After the mix stops bubbling, use an old toothbrush to work the leftover wet baking soda into the strip of silicone caulk. Let that sit for a few minutes before thoroughly rinsing and drying. Or you can make a paste of equal parts baking soda and water and apply that to the mildew on the caulking. Scrub it into the caulking and let it sit for 20 minutes or until dry before rinsing off and drying well.

Bleach to Remove Mildew

Using straight bleach to take out mildew or spots of mold can be problematic. Noxious fumes from the harsh cleaner can build up in small spaces and be overwhelming. When using bleach, the area needs to be well ventilated.

Molly Maid recommends mixing a solution of 1 part bleach to 10 parts of water and leaving it on the caulking for at least five minutes. Use the rough side of a dish scrubbing sponge to work the bleach into the caulking before rinsing.


Kimberley McGee is an award-winning journalist with 20+ years of experience writing for a variety of clients, including The New York Times, Las Vegas Review-Journal Home section and other national publications. As a professional writer she has researched, interviewed sources and written about home improvement, interior design and related business trends. She earned a B.A. in Journalism from the University of Nevada, Las Vegas. Her full bio and clips can be viewed at

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