How to Caulk a Bathroom Sink with Flex Shot

“How to Caulk a Bathroom Sink With Flex Shot” was written by a member of the Flex Seal Editorial Team. 

So, you have a seam behind your bathroom sink that separates it from the wall. No big deal, right? Not exactly. As steam and water get behind the sink, it creates an ideal environment for mold and mildew, potentially leading to costly damage to your wall. The good news? Flex Shot can easily seal seams and make them look nice, too. Keep reading to learn how to caulk a bathroom sink using Flex Shot.

Materials Needed

● Flex Shot (colour of choice) 

● Box cutter or knife

● Paper towels

● Optional: Caulk remover and razor scraper

Note: Before using Flex Shot, read all directions carefully and take proper safety precautions, such as being in a well-ventilated area and wearing protective gear while applying. 

1. Getting Ready to Use Flex Shot

Start by removing any old caulk along the areas where you’ll apply Flex Shot. To do this, run a caulk remover along the previous caulk line and use a razor scraper to remove any remaining bits. Then, make sure your project area is clean, dry, and free from grime, mildew or dirt.

Now that the surface is prepped grab your can of Flex Shot and a box cutter or knife. Carefully cut the tip of the extension tube at a 45-degree angle so that it’s large enough to achieve the desired bead size. Please use caution when doing so.

Flexpert Tip: The farther down you cut the extension tube, the larger the bead size. 

2. How to Caulk Around a Bathroom Sink With Flex Shot 

For this DIY caulking project, we suggest using Flex Shot white or almond since they are mildew resistant. To apply, simply press the extension tube to dispense the product. For a perfect bead, use a steady, even motion, making sure to fill in all the gaps along the back of the sink where it meets the wall. Be sure to use a large enough bead to not leave any space for leaks to sneak through.

Flexpert Tip: You can control the size of the bead by adjusting how fast you move through the area you’re caulking. Slower speed, thicker bead.

3. Finishing Up and Storing Your Flex Shot

Flex Shot can be tooled within 20 minutes of application, so once your desired areas have been treated, take your finger or a caulking spatula and smooth out the product. Use a paper towel to remove any excess Flex Shot and allow approximately 24-48 hours for the product to fully cure.

Flexpert Tip: We do not recommend cleaning with harsh chemicals or scrubbing as this may cause the product to become slippery or break down.  

Once fully cured Flex Shot remains flexible and waterproof and will not fade, dry, shrink, crack, yellow, or deteriorate. This makes it perfect for protecting your sink and bathroom walls for years to come.

Now that your DIY sink caulking project is complete, it’s time to store Flex Shot properly. Remove the extension tube and clean it with a dry paper towel. Extend a small bead past the applicator tip to form a plug. This plug will cure and help the remaining product stay fresh. Simply pull or cut off this plug when ready to reuse.



By Amanda Tacconi 

Amanda Tacconi is an Editor at The Flex Seal Family of Products, where she focuses on writing and editing articles for the company’s blog.

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