The letters below are composites of the questions we hear all the time, in hardware aisles, at backyard barbecues, and from anyone who finds out what we do for a living. Names and places have been changed, mostly for alliteration.
Can I just caulk over the old stuff?
Dear Rosie, the caulk around my tub looks tired but it's mostly still there. Can I just run a fresh bead right over it? It would save me a whole afternoon.
Signed, Layering in Lansing
Dear Layering, I love you, and no.
New caulk needs to grab a clean, solid surface. If you lay it over the old bead, it bonds to the old bead, which is exactly the part that's failing. And if that old bead is silicone, which around a tub it usually is, the new caulk won't bond to it at all. You'll get a nice-looking line that peels off in a few weeks, with mold happily growing in the layer between.
Spend the afternoon. Cut out the old caulk, clean off the film, dry the joint, and start fresh. Our removal guide makes it go faster than you think. The only time caulk-on-caulk is fine is a thin touch-up pass of latex over a latex bead you laid yourself that shrank as it dried.
My roommate used silicone on the baseboards
Dear Rosie, my roommate "helped" by caulking all our baseboards with clear silicone. Now we're painting, and the paint just beads up and peels off the caulk. Help?
Signed, Painted Into a Corner
Dear Painted, your roommate's heart was in the right place, and their caulk was not.
Standard 100% silicone can't be painted. Paint simply won't hold on it. There are a few specialty "paintable silicone" products, but results vary, and they won't rescue what's already there. The fix is to remove it: slice it out, then scrub the joints with mineral spirits or isopropyl alcohol to get rid of the slick film. Then caulk with a paintable acrylic latex and paint once it's ready. For a tube we like on trim, see our painter's caulk review.
Afterward, maybe send your roommate our Which Caulk Are You? quiz. It's a gentle way to start a conversation.
How long do I really have to wait before I shower?
Dear Rosie, I re-caulked the shower this morning. The tube says to wait 24 hours. Is that serious? I have a date tonight.
Signed, Getting Ripe in Reno
Dear Ripe, it's serious, and I say that with deep sympathy for your date.
Silicone cures by reacting with moisture in the air, from the surface inward, and it needs time to cure through before water hits it. Showering early can wash out the surface, leave the bead soft underneath, and set you up for leaks and mildew. Some fast-cure silicones advertise much shorter shower-ready times, and if yours does, go by the tube. If it says 24 hours, give it 24 hours, and a little longer if your bathroom is cold or the air is very dry. Siliconized acrylic caulks can take longer than silicone before they're happy with regular soaking.
In the meantime: the gym, a kind neighbor, or the sink. Tell your date it's a caulking thing. The right person will understand.
The gap under my baseboard is huge
Dear Rosie, there's a 3/4-inch gap between my baseboard and the floor. How many tubes of caulk will it take to fill?
Signed, Gap-Toothed in Galveston
Dear Gap-Toothed, more than you'd like, and it won't work anyway.
Caulk is for joints, not canyons. A 3/4-inch bead of latex will sag, shrink into a gully as it dries, and crack the first time the floor moves. The classic fix for a big gap at the floor is trim: a strip of shoe molding or quarter round nailed to the baseboard hides the gap completely, and then you caulk the small joints it leaves. If you really need to seal a wide gap, push in backer rod first so the caulk ends up a sensible size; our backer rod guide explains how. And it's worth asking why the gap is there. A floor that's settling may be telling you something.
For smaller gaps, the tube calculator will tell you exactly how many tubes to buy.
My clear caulk came out white
Dear Rosie, I bought clear caulk for my backsplash, but it came out of the tube bright white. Did the store give me the wrong one?
Signed, Cloudy in Cleveland
Dear Cloudy, probably not. Breathe.
Water-based "clear" caulks go on milky white and turn clear as the water evaporates. A thin bead might clear overnight; a thick one can take several days, and cool or humid weather slows it down. Give it time. Clear silicone, on the other hand, looks clear-ish straight from the tube. If a water-based clear bead is still cloudy after a week of mild weather, it may be too thick to dry through, or the tube may have frozen at some point. More on colors and clarity in the caulk aisle, decoded.
Why does my exterior caulk crack every winter?
Dear Rosie, every spring I re-caulk the trim on my house, and every winter it cracks again. I'm starting to take it personally.
Signed, Cracked in Cheyenne
Dear Cracked, it isn't personal. It's physics.
Outdoor joints open and close as the seasons change, and that movement is biggest in exactly the places you're caulking. Basic acrylic latex can't stretch very far, and if the joint is too narrow, too shallow, or bonded on three sides, even a good sealant will tear. Here's the fix:
- Switch to a high-movement exterior sealant, like an elastomeric, polyurethane, or hybrid. Look for ASTM C920 and a movement class of 25 or better. Our reviews of Sashco Big Stretch and OSI Quad Max are good places to start.
- Use backer rod or bond-breaker tape so the bead only sticks to two sides. See three-sided adhesion.
- Caulk in mild weather, so the joint is mid-range when you seal it. The weather guide explains why.
Do those three things, and next spring you can spend your weekend doing something else. Like caulking something new.
Should I caulk the bottom of my windows outside?
Dear Rosie, I'm sealing up my windows before winter. Do I caulk all the way around the outside, bottom included?
Signed, Weeping in Walla Walla
Dear Weeping, what a good question, and the answer is: check before you seal the bottom.
Windows are designed to shed water, and many need a way to let out any water that gets inside the frame or behind the trim. Vinyl and aluminum windows often have small weep holes or slots along the bottom of the frame. Never caulk those shut. Many window makers and installation guides also call for leaving part or all of the bottom edge of the exterior trim or flange unsealed, so water behind it can drain out instead of being trapped. The sides and top are usually sealed. Your window maker's instructions are the final word, so look them up for your model. Our windows and doors guide covers the rest.
Is it weird that I find caulking relaxing?
Dear Rosie, I re-caulked my kitchen last weekend and it was the most peaceful afternoon I've had in months. I'm thinking about doing the bathroom just for fun. Is something wrong with me?
Signed, Bead-Curious in Boise
Dear Bead-Curious, there is nothing wrong with you. There is, if anything, something very right.
Caulking is slow, steady, and deeply satisfying. It asks for your full attention for a few minutes at a time, rewards patience, and leaves you with a clean, finished line that makes your home a little better. Plenty of people find that restful. You're among friends here. Very serious friends.
Go do the bathroom. Then, when you run out of joints, come play Bead Master or try the caulk crossword. Welcome to the club.
Keep your beads smooth,
Rosie
We can't answer individual letters, but chances are your question is already in our FAQ.