The Two Best Caulks for Small Home Projects
We put eight caulks and sealants to the test in our labs—we evaluated cure time, durability, adhesion, and more
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I’m a renter so I’ve never had to caulk a bathtub or seal a joint in concrete, but I’ve watched as my dad sealed a hole around a doorframe or window with a caulk gun in my family home. He’s never described himself as a handy person and it shows—it’s always a messy, time-consuming ordeal for him. Sure, he could just hire a professional, but when you have a small enough gap to fill, doing the work yourself can be simpler than finding a contractor and less expensive, and earns you bragging rights with your less handy friends.
- The Products We Liked: DAP Kwik Seal Flex Seal
- More on Caulks and Selants: Caulks v. Sealants Caulks You Can Skip Where Shouldn't You Use Caulk? How We Tested Caulks and Sealants
See CR's Caulk Test in Action
What Is the Difference Between Caulk and Sealant?
Caulk and sealant are often used interchangeably. On some of the products we tested, both terms were used right in the product name, but there is a difference between the two. Both can be used to fill and seal gaps around and outside a home. Once dry, caulk is usually stiff and inflexible, so it is better suited for areas with little movement, like baseboards and window frames, to avoid cracking. Sealants are a little bit flexible and are better suited for bathrooms, kitchens, and outdoor applications where they may be exposed to moisture, movement, and temperature fluctuations, and are usually made from silicone and cannot be painted. Caulk is made from acrylic or latex and can be painted once cured (the time it takes for the caulk to completely dry and become impermeable to water).
Flex Seal’s Flex Caulk was the best performer in four of the five tests we put each product through in our labs. It had the best adhesion to painted wood and ceramic tiles and was impermeable to water instantly, even though it had a 24-hour cure time. Several brands had shorter water permeability claims than the time required for the caulk to totally cure.
It also did not crack when it was exposed to freezing and hot temperatures and was the easiest of all the products to dispense. However, it is the most expensive caulk we tested (based on the price at the time of publishing), so if you’re working on a large project that requires large amounts of caulk, it isn’t the best option, if you’re looking for cost savings. According to the brand, this caulk “lasts for years” and is also sold in a 100 percent silicone formula, but we didn’t include that version in our tests.
This caulk is packaged in a pressurized container with a built-in dispenser, so there is no need for a caulk gun, making it easier to dispense. Unlike many other caulks, you don’t have to cut the tip to size. Instead, the flow of caulk dispensed is controlled by twisting the top—the only product we tested that offered this feature. Amézquita and two CR technicians also found it very easy to dispense. After using, place the cap back on the top to prevent it from drying out before your next use.
*Based on Amazon price at time of publication.
DAP Kwik Seal Kitchen & Bath Adhesive Caulk was the second-best performer in our tests. Like our Editor’s Choice from Flex Seal, the 5.5-fluid-ounce tube does not require a caulk gun to dispense. Instead, you just have to cut the top of the tube and squeeze the amount of caulk you need manually, like dispensing toothpaste. Just like squeezing a tube of toothpaste, squeezing from the bottom of this tube of caulk is the best way to dispense it, according to Amézquita.
Like with the caulks that require a caulk gun, once you cut the tip, there’s no changing the size of the hole the caulk is dispensed from, unless you start with a smaller hole and then cut it larger. Though this product is simpler to use than a caulk with a gun, it is thicker and harder to push through the tube, so those who struggle with weakness in the hands (like those who suffer from arthritis or carpal tunnel syndrome) may find DAP difficult to use. It ranked third in our ease of dispensing tests.
Although it was not the top performer in any of the tests we conducted, it cost just 88 cents per ounce (at Walmart.com at the time of publishing), had the second-best adhesion to painted wood, and showed no changes after being exposed to extreme cold and hot temperatures for several days. The label recommends this caulk be used for kitchen, bath, and plumbing applications. It has a one-year warranty and, like most other caulks, can be painted once cured. Like the Flex Caulk, it also has a cap so that you can avoid having the caulk dry out between uses.
*Based on Walmart price at time of publishing.
Caulks You Can Skip
Most other caulks and sealants we tested worked well enough—they didn’t excel in our tests to highlight individually, but depending on the job, they should be fine to use for home projects. The other caulks and sealants we tested were: GE Advanced Silicone Caulk for Kitchen & Bathroom, Gorilla Waterproof Caulk & Seal Silicone Sealant, Loctite Polyseamseal Tub & Tile Adhesive Caulk, and White Lightning Painter’s Preferred All Purpose Acrylic Latex Caulk. Two additional products below, a caulk and a sealant, performed poorly in the tests in which some others excelled.
DAP Alex Plus All Purpose Acrylic Latex Caulk Plus Silicone was among the worst in our adhesion and permeability tests. The adhesion of this caulk was poor on both painted wood and ceramic tiles. After allowing it to cure for 24 hours, the skin that formed on the surface of this caulk was thin and still spread when pressed with a finger. It was also the only caulk that cracked after being exposed to temperatures of minus 6° F and 100° F for 24 hours each. It was the most cost-effective model, at 39 cents per ounce.
After 24 hours of cure time, Sashco Lexel Elastic Sealant had the worst adhesion to painted wood and ceramic tiles, even though it had the longest list of recommended surfaces on the label. According to the label, it can take up to 14 days to cure completely. Two of the caulks we tested had the same curing times on their label but displayed a better performance in adhesion after just 24 hours of curing than this sealant. In our dispensing, temperature durability, and skin removal tests, it showed an average performance.
Where Shouldn't You Use Caulk?
As useful as caulk is to fill gaps, there are some places you should avoid applying it to. Paul Hope, CR’s deputy content editor for home, says you don’t want to apply it to things that open and close, like the sash of windows. If you want to open them again, you’ll have to remove the caulk. “’I’d also say it’s not the right material choice for every situation. Larger holes in wood, for example, might be better filled with wood filler.”
He also stressed choosing the right type of caulking for the project you’re working on. For example, silicone caulk is more water- and weather-resistant, so it’s a good option for bathrooms and other areas that may be exposed to water often. But it can’t be painted, “so the issue is you won’t want to use that on any spots that you might want to paint on the exterior, like wood trim,” says Hope.
In our testing, we found that the fine print on caulk labels included extensive lists of surfaces they work best on. We suggest reading those labels closely to ensure you’re choosing the right caulk for your project.
How We Tested Caulks and Sealants
We tested caulks and sealants for their adhesion, ease of dispensing, permeability, cure time, durability at cold and hot temperatures, and ease of removal from skin.
For our adhesion tests, we dispensed each product in the following ways:
• In a zigzag pattern to adhere two pieces of painted wood together
• In a straight line to adhere two pieces of painted wood together
• In a straight line to adhere two ceramic tiles face to face
• In a straight line to adhere two ceramic tiles face to back
After curing for 24 hours, force was applied until the pieces were separated or the maximum force CR tester Amézquita could apply to them was reached. One of the sets of ceramic tiles was submerged in water during the adhesion test to determine whether water would weaken the caulk’s adhesive ability.
Our durability test involved placing a caulked wood joint that had been allowed to cure for five days in a minus 6° F walk-in freezer for 24 hours. Then it was transferred into an oven set to 100° F. A second caulked wood joint was placed in a 100° F oven and then moved into a minus 6° F freezer. Both joints were inspected for cracking, shrinking, or any other changes.
Four ceramic tiles were used to conduct permeability and cure time tests after 15 minutes, 30 minutes, 24 hours, and several days. Water was dripped over the caulk to see whether it would roll off. The stiffness and skin (the hardened layer that forms on the surface of the drying caulk) of each model were also noted.
Two CR technicians, Jonathan Tuczynski and Matthew Guayara, dispensed two lines of each caulk to evaluate their ease of use. For the models that required a caulk gun to dispense, the same gun was used by both technicians. To assess the ease of removing each product from the skin, Amézquita dispensed about ½ inch of caulk on his forearm, let it stand for 30 minutes, then removed it with warm water and soap or with his fingers, if necessary. In our tests, Gorilla Waterproof Caulk & Seal 100% Silicone Sealant was the trickiest product to remove from his skin. Note that you should not apply caulk directly to the skin, so we do not recommend replicating this test at home. If any caulk ends up on your skin during use, wash it off immediately with warm water and soap.
