| |



A protective caulk is a waterproof sealant that is commonly used in home-based repair works or even new domestic fittings. The purpose of caulking is to prevent water damage and offer other sealing solutions.

Caulking an undermount sink, in this case, is an important home improvement DIY project that helps prevent water from leaking underneath the sink. Almost all undermount sinks are known to leak from the recessed edges (if a protective sealant/adhesive is not applied correctly).

We’ve followed sink formula, a sink plumbing blog to write this informational article about caulking an undermount sink.

The process of caulking an undermount sink is, however, essential if you have the correct step-by-step guide.

How to Caulk Undermount Sink:

Homeowners and DIY’ers want to know how to caulk undermount sink.

Usually, there are seven steps involved for a successful outcome.

As opposed to the drop-in sink, you risk having water damage and mold formation underneath the sink cabinets if you do not caulk an undermount sink.

Step-by-Step Guide

Items and Tools You’ll Require:

Caulking under-mount Sink the traditional way is not only messy. It is an unprofessional style that leaves faults. So, to get the job done correctly, you need the necessary tools and utilities.


  • Premium kitchen caulk
  • Tack cloth
  • Caulk gun
  • Spatula/flat putty stick (if needed)
  • Scraper or a retractable utility knife

Safety equipment

  • Safety gloves

Step 1: Choose the correct caulk

Kitchen caulks are available in diverse brands and types. You have the general-purpose caulk, standard latex caulk, and the outdoor butyl rubber caul for instance.

So, for most kitchen use, the standard latex caulk is the correct sealant to consider.

Thus, purchase the correct kitchen caulk right before you begin to caulk undermount sink.

Step 2: Cleaning the surface

Clean the surface with soap & water for first time caulking. If you want to reseal an undermount sink, you need to first remove the old caulk using a scraper or any other similar tool.

You should use the retractable pen knife to remove old caulk from the countertop and sink corners.

Also, you can alternatively use scouring powder for a more detailed countertop scrubbing. Finish prepping the countertop with rubbing alcohol.

Step 3: Applying tape on the working surface

Applying duct tape, masking tape, or any other similar alternative along the edges of the working surface can help achieve cleaner results.

Apply straight strips about ¼ of an inch from the edges of the undermount sink and the countertop.

Step 4: Applying caulk on the undermount sink

First, cut the tip of the caulk tube with a utility knife. Note that you should follow the manufacturer’s guide.

Next, insert the caulk tube on the caulk gun before you begging the delicate caulking process.

– Operating a caulk gun:

Usually, you need to hold the caulk gun at a 45◦ angle. Squeeze the gun handle until the caulk begins to ooze smoothly from the tip of the tube.

Start slowly but consistently as you progress through the entire work surface.

Step 5: Smoothing the caulk

After applying enough amount of caulk to the entire surface, you should smooth it off.

Use a spatula and a dump cloth to smooth off the caulk. Once the caulk is evenly smoothed off, you need to confirm that there are no air spaces trapped along the undermount and countertop edges.

In most cases, people use their fingers to smooth off the caulk. However, you can use a spatula or flat stick.

Step 6: Removing the tape

Removing the tape and removing the excess caulk is a straightforward process. However, before you remove the tape, you need to check if the caulk is completely dry.

The average drying time for a standard caulk is between an hour or even two.

Slowly and carefully pull the tape away from the countertop to avoid peeling off the pre-installed caulk.

Step 7 (optional): Painting the caulk

Although painting the caulk is optional, it is a unique way to complete the countertop’s appearance.

How to do it: Wait for the caulk to cure completely before applying three coats of your preferred paint.

Pro Tip.

Caulking tape is another great alternative to consider

You need to apply enough strips of the recommended caulking tape along the outer edges of the countertop as well as underneath the undermount basin. Apply straight strips (about ¼ of an inch from the edges) for a more professional outcome.

The painter’s tape and magic peel are two recommended caulking tapes to always consider. These caulk tapes are available in both narrow and wide sizes.

Also, before we forget, you should cut mitre edges on the caulk tape to facilitate easy tape installation around the corners.

Caulking tape can be used to reseal an undermount sink.

How to Caulk a Stainless Steel Sink on Tile

A stainless steel sink that is sitting on top of tiles can be easy to caulk. You not only need the necessary tools in this case. You need the expertise and a guide for cleaner results. An undermount stainless steel sink, on the other hand, can be a bit tricky.

Here are all the necessary steps to follow.

  1. Choose the correct caulk: Note that not all caulk will stick on tiles or even the stainless steel material (non-porous materials). The silicone caulk, in this case, offers the best service compared to the other available options.
  2. Prep the surface: Next, ensure that both the stainless steel sink and tiles are clean and dry before you apply the caulk. You can use water and dish wash detergent to clean the surfaces.
  3. Allow the surface to dry completely: After rinsing the surfaces, you should give it enough time to dry completely. (Probably an hour or so)
  4. Tape the tile and the stainless steel sink: Applying tape on the surface ensures a much cleaner result.
  5. Install silicone caulk on the caulk gun: Carefully fit the silicone caulk tube on the caulk gun prior to beginning the caulking process.
  6. Applying caulk on the surfaces:

Squeeze the gun handle until the silicone begins to ooze from the caulk tube. Apply the caulk evenly along the edges of the tiles and the stainless steel sink.

For drop-in sinks, you should first lift the sink (at a reasonably sufficient height) and apply enough amount of caulk on the tile’s surface. Then, lay the sink on top of the caulk and leave it to dry.

Note: If the silicone caulk does not bond precisely with the stainless steel surface and tile, you should try to apply grout then reapply the caulk.


Caulking a sink not only gives it a fresh new beginning. Caulking ensures that there is no more water leakage that eventually damages the cabinets. Additionally, maintaining the caulk on an undermount granite kitchen sink ensures quality service.

With the above step-by-step guide, you should know what to do and what to consider when caulking an undermount sink.

So, if you were doubtful about caulking an undermount or even a drop-in sink, now you have a guide to help you.

Sharing is caring!

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.