How to Caulk a Bathroom Sink (The Complete Guide)

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Over time caulk can develop black mold or dry and crack around a bathroom sink. This it can look very ugly but more importantly, when the seal cracks, it could lead to water leaking under the sink.

Removing old caulk and then re-caulking a bathroom sink may seem like a daunting job, but it’s really not that difficult.

In this guide, we will walk you through the entire process of how to caulk a bathroom sink step-by-step. We’ll start by explaining what caulk is and how to remove the existing caulk from your sink. Then we’ll show you how to apply the new caulk in a neat and professional manner.

Let’s get started!

What Is Caulk?

Gorilla Waterproof Caulk & Seal 100% Silicone Sealant

Typically, caulk these days is made of latex and silicone, but it wasn’t always the case. It came along when sailors needed a form of sealant for their boats and ships, so they used cotton dipped in a tax mixture which was stuffed into the gaps to create a seal, be it not a very good or long-lasting one.

Eventually, a soft silicone gel was created that was at first in a liquid form but, when dry, would stick to the surface and harden into a type of waterproof rubber material while creating a seal, making it perfect for caulking the bathroom.

When caulking any surface in the bathroom, it is important to remember that the surface will determine whether you need to use a latex or silicone caulk to get a seal that lasts the test of time. For instance, when caulking a porcelain or stone sink, it is best to use latex, while silicone is best suited for surfaces made of metal such as copper or stainless steel.

The caulk is available in different colors to best match the surface of the sink to give you that professional finished look.

How To Remove Existing Caulk From The Sink

removing caulk
Photo by Yellow Brick Home

Before we start to caulk the sink, the old caulk needs to be removed and the surrounding surface cleaned. However, if this is a brand-new installation, you can skip this part.

Materials and tools

  • Blade 
  • Denatured Alcohol or Acetone
  • Hot water
  • Towels, cloth/paper
  • Sponge

Directions

Step 1 -Soften the Caulk

If the existing caulk is water-based, then dip your cloth in hot water and place it over the caulk; however, if the caulk is silicone based, then dip the cloth in acetone or denatured alcohol.

Step – 2 Cut the Caulk

Leave the cloth on the caulk for 20 minutes allowing the caulk to soften, which will make it easier to cut out. Take the blade and cut the caulk out completely, ensuring to remove any small bits left behind.

Step – 3 Clean the Surface

For the new caulk to be effective, you will need to make sure the area is completely clean. Use a nonabrasive sponge with either hot water or acetone to remove any leftover residue.

How To Apply New Caulk To A Bathroom Sink

Apply New Caulk To A Bathroom Sink

You can find entire rows of shelves full of different caulks or sealants in your local hardware store. However, there are a few things you will need to consider before going out and buying that tube of silicone or latex caulk.

Silicone caulk is best suited for metal surfaces such as copper or stainless steel. Alternatively, if you have a farmhouse porcelain or ceramic sink, then a latex caulk is a much better option.

There are also various colors and shades available now, so finding one that matches your surroundings should not be difficult; however, if you can’t decide which color caulk to get, then you could simply opt for the clear gel.

What You Need

Gorilla Waterproof Caulk & Seal 100% Silicone Sealant, 10oz Cartridge, White (Pack of 1)

Caulk (silicone/latex)

Red Devil 3989 9" Extreme Duty Caulk Gun - Thrust Ratio 26:1,Black

Caulk gun

Amazon Basics Masking Tape, 0.7 Inch x 180 Feet - Pack of 3 Rolls

Tape (masking or painters)

Homax Perfect Bead Caulk Finisher, Black

Caulk smoothing tool

Directions

1. Clean and Tape

Every time you approach the sink, you will inevitably stare at the caulk, so you need to make sure that you do a neat, clean, and professional job.

Before starting the caulking process, ensure the surface around the sink is clean and dry; otherwise, the caulk will not be able to do its job properly.

To get the perfect line and with minimum mess, apply tape on the tiles and the sink surface, leaving a 2mm to 3mm gap where the two surfaces meet for the caulk.

2. Apply the Caulk

Use the caulk gun to slowly apply an even bead of caulk around the sink in between the tape, ensuring you maintain even pressure on the gap. Start at one stop when the caulk gun needs re-loading.

3. Smooth the Caulk

Grab the caulk smoothing tool and ease over the caulk bead smoothing the caulk, ensuring there are no bubbles or streaks.

4. Remove the Tape

Once you are satisfied with the caulk around the sink, you can proceed to remove the tape. Slowly peel the tape off, revealing a beautiful straight, smooth line of caulk on your sink.

5. Dry

The caulk needs time in order to cure, so wait at least 16- to 24 hours before using the sink. Fresh caulk may allow water to seep through, so it is essential the caulk does not get wet.

FAQS Frequently Asked Questions

Why do I need to tape my sink or bathtub when caulking?

This can be quite a messy job if you are not careful when caulking. Applying tape will not only give you a professional clean finish, but it will potentially save you time cleaning the tiles or bathtub and sink after.

Can I fill large holes with caulk?

The short answer is no. Typically, you should try to keep the width of the caulk under a quarter inch and the depth no more than half an inch. A caulk backer rod should be used in larger gaps, filling the gap and caulking on top, creating a lasting seal.

How do I caulk a bathtub?

The weight of the water will generally shift the bathtub stretching the caulk over time. To prevent this from happening, fill the bathtub with water before caulking. Ensure the area is clean and dry. Apply the tape on the tiles and the bathtub surface, ensuring you get a straight line and avoid any mess.

What is the difference between latex and silicone caulk?

The main difference between the two is that they are used on different materials. Silicone-based caulk is typically used for metal surfaces and glass. Latex-based caulk is used for surfaces such as ceramic, porcelain, and wood.

How long will a sink or bathtub caulk last?

A sink or bathtub caulk can last up to 10 years, depending on maintenance. If the sink and bathtub are regularly cleaned and dried after use, then it can prolong the life of the caulk.

Can I put the new caulk over the old caulk?

In most cases, you want to put caulk on your sink or bathtub because either the old caulk has split and is leaking or has mold growing on it. Putting new caulk over the old will not only look ugly, but it won’t solve any of the issues you are experiencing.

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