Bathtub Caulking Tips

How to achieve smooth caulk.

If a lumpy caulk job bugs you, check out these tips to help anyone learn to run a smooth bead of caulk. With advice from a pro painter and a tile setter, you'll soon be caulking everything around the house.

By the DIY experts of The Family Handyman Magazine

Overview

I'm always surprised when people ask, “How do you get such a smooth bead of caulk?” For me it seems easy and I usually just reply that it takes practice. But after talking with a painter and a tile setter who both spend a lot of time caulking, I discovered a few techniques that will cut the practice time to a minimum. You can get good results right away. In this article, we'll show you how to get a neat caulk bead around a bathtub, but you can use the same techniques for other caulking as well.

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A nice bead starts with a well-prepared tip

The biggest mistake most people make is cutting too much off the tip of the caulk tube. In general, the size of the hole should be about two-thirds the width of the desired caulk joint. Most caulking jobs around the home only require a narrow bead. If you're caulking woodwork to prepare it for paint, start with the opening very small, just over 1/16 in. diameter. For tub caulking, a 1/8-in. diameter hole is usually about right. Some caulk tubes need to be punched in order to start the flow of caulk. Nails aren't always long enough. Use a thin, stiff wire like a scrap electrical wire or coat hanger to avoid enlarging the hole at the tip.

You'll notice 45-degree marks on the tips of some caulk tubes, indicating the angle you should cut the tube. But some pros recommend a blunter tip angle, about 60 degrees. Give it a try. You can always cut the steeper, 45-degree angle if you don't like it. Regardless of the angle of the cut, the key is to hold the caulk gun at this same angle while you're filling the joint.

A smooth tip makes a smooth bead. So use a sharp knife to cut the tip, and follow up by smoothing the tip with fine sandpaper (close-up photo).

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Match your caulking speed to the size of the bead

To apply a smooth bead of caulk that's just the right size, you have to find the best balance between pressure on the handle and application speed. The trick is to keep the pressure constant and vary the speed according to the size of the joint. To get a small, fine bead of caulk, you've got to move the tip along the joint at a rapid clip. Keep the caulk gun at the same angle and try to fill the joint as you go, but don't worry if you leave a gap. It's easier to make a second high-speed pass than it is to clean up excess caulk from going too slowly. You can slow down a little for larger caulk joints, but keep the speed steady.

Squeeze the caulk gun handle steadily to maintain an even flow of caulk (Photo 3). Keep the gun moving as you let up and give the handle another squeeze. When you reach the end, quickly lift the tip from the surface and release pressure. Clean excess caulk from the tip before you start a new bead (Photo 2).

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Smooth the caulk with your finger

Smoothing not only makes the caulk look good—it ensures good adhesion on each side of the gap. Forget about special tools. Just use the tip of your finger (Photo 4). Wet your finger with water for latex caulk. Then use a wet rag to clean off your fingertip. Rinse the rag often. If you're using silicone caulk, wear a tight-fitting latex or vinyl glove and wet the fingertip with denatured alcohol. Keep your beads of silicone and urethane caulk slim to make smoothing easier. If you get much excess, they're hard to clean up and things can get really messy if you keep wiping your finger on the same rag. Use paper towels or a roll of toilet paper instead so you can use a new piece every time you wipe off your finger.

Choosing a Caulking Gun

I've talked to pros who swear by the expensive frame-type guns instead of the more common cradle-type (photos below). If you do a lot of caulking, it may be worth spending $15 to $20 for one of these. I admit they work smoothly and are easy to use. But for my money, a medium-priced (about $5) “dripless” gun is the way to go. Look for the “dripless” label on the gun. These are designed to take pressure off the tube as soon as you release the handle so you don't end up with a river of caulk flowing out every time you set the gun down. I also prefer a gun with a smooth rod, without notches.

Frame- and cradle-style caulking guns
Use Masking Tape for Perfect Caulk Joints

It takes a little longer, but the technique shown in Photos 1 and 2 below makes it easy to get a perfect caulk joint every time. This tip is handy if you're using silicone caulk because cleaning up excess silicone is always difficult. Place two strips of masking tape about 3/16 in. apart where you want the caulk joint. Be careful to keep the lines straight and an even distance apart. Press the tape tight to the surface, especially at grout joints or other depressions, so caulk doesn't ooze under the tape.

Apply two strips of masking tape, leaving space
between them for the desired caulk joint width. Lay
a bead of caulk and smooth it with your fingertip.

Immediately pull the tape away from the caulk at an
angle as shown.
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Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • Caulk gun
  • Painters tape
  • Rags
  • Utility knife

You'll also need sandpaper.

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

  • Caulk