Q: I remodeled my kitchen three years ago, upgrading to granite counters and a stainless steel sink, mounted from below. The contractor put caulk around the sink to seal the gap between it and the counter. Now, there is quite a bit of black mold on the caulk.
What can I do to get rid of the mold? Should I get the sink re-caulked?
A: We think what you describe as mold is more commonly known as mildew, a fungus that appears as a dull black mold, often with a musty smell. It thrives in hot, humid places: your kitchen qualifies.
The best way to remove mildew is to eliminate dampness and improve ventilation. Since eliminating water is impossible in a kitchen sink, the best way to attack the mildew is to kill it.
With any luck, getting rid of the mildew around your sink should be easy. You can kill it by applying chlorine bleach–any brand will do–full-strength to the caulk.
Use a small sponge to apply the bleach and be careful not to get it on you, your clothes or anything else you don’t want bleached.
Because you remodeled your kitchen fairly recently, we don’t think the mildew has had enough time to penetrate the caulk. It’s likely that what you see is superficial. A good dousing with bleach will make it disappear like magic; no re-caulking necessary.
But if we’re wrong and you have to replace the caulk, there’s good news and bad news. The good news is that a re-caulk job is cheap and you can do it yourself. The bad news is that you have to do it at all after three years.
Dig the old caulk out with a chisel or the tip of a flat-head screwdriver. Once the old caulk is totally removed, clean the surface. Your stainless steel sink won’t take kindly to being cleaned with an abrasive like an SOS pad. Use a Scotch-Brite pad.
After the surface is thoroughly dry, it’s time to apply the new caulk. The best caulk for use around a sink is a tub and tile caulk. Any hardware store will have it. Caulk comes in different colors. If you aren’t able to find one that suits you, consider using clear silicone caulk.
For a professional job, apply masking tape on each side of the joint to ensure a straight and uniform line. Apply the caulk in an even flow. Then dip your finger in water (mineral spirits if you’re using a silicone) and run it along the seam to get a smooth finish.
Wait a few minutes until the caulk has set a little, then pull the masking tape away from the joint. The wait ensures that the caulk won’t smear. If you let it dry thoroughly before removing the tape, you risk pulling the caulk out with the tape.
Take your time, and with a little care, you’ll have a perfectly clean, re-caulked and good-as-new kitchen sink. To prevent having to repeat the process, do an occasional cleanup with chlorine bleach to nip mildew discoloration in the bud.
By the way, chlorine bleach also works great to get rid of mildew in tiled showers. No need for special products. Full strength in a spray bottle is the way to go.
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