10 tips for a better caulking job

How to get clean, weathertight seals

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Caulking seems like a pretty easy thing to do, and all in all it is. But there are some tricks of the trade that can make a big difference between a smooth, hassle-free caulking job and one that’s frustrating and perhaps a little sloppier than you’d like. So before your next caulking project, here are a few things to keep in mind.

Gather up a few simple tools

For any caulking job, you need only a handful of basic items, all of which are available at any home center, hardware store or paint store.

First of all, you’ll need a good-quality caulking gun. Skip the 99-cent bin and those low-end guns that utilize a ratcheting plunger, easily recognized by the series of notches cut into the plunger’s shaft. Ratcheting guns don’t operate smoothly, so it’s hard to apply a clean, uniform bead.

Instead, for around $10 you can buy a pro-grade gun, which has a couple of moveable plates that grip a smooth plunger rod. The action is much smoother, and it’s also easier to release, so you have less wasted caulk dripping out of the tube. Ideally, the gun you select should also have a rotating barrel, a rod for puncturing the caulking tubes, and hook on the end for hanging the gun (more on that in a moment).

In addition to the caulking gun, you’ll need a 5-gallon bucket, several rags, a utility knife, and some disposable gloves. If you have large gaps to fill, you’ll also need some foam backer rod, as described below.

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Prepare the joints

First of all, you need to prepare the areas that you’re going to be caulking. Like anything else, if the area is dirty, dusty, wet or filled with debris, you won’t get the results you want. Use a brush, putty knife, compressed air, or other appropriate tools and techniques to clean out the cracks you want to caulk. If you’re repainting, be sure that any old paint is cleared out. On new wood, be sure the wood is dry and free of sawdust, and has shrunk as much as possible.

The manufacturer’s directions on the caulking product you’re using will specify how large of a gap that particular caulk will fill without sagging — typically 1/4 to 3/8 of an inch in width. If you try to fill anything wider that what the caulking is rated for, it will simply sag into the gap or the caulk film will split; either way, it means an unsightly caulking job that’s not weathertight.

The solution is to use what’s known as a backer rod. This is simply a round foam rod, which is sold by the roll in different diameters. Use a rod that’s slightly larger in diameter than the gap, so that it compresses into the opening. Cut the rod to the desired length, then press it into the gap so that it’s slightly below the surrounding surfaces. You can then caulk the gap on top of the backer rod, without worrying about the caulk sagging into the gap.

A few simple techniques

One of the easiest ways to ensure that the caulking bead isn’t too large and sloppy is to start with a small bead in the first place. To do that, use your utility knife to cut the end of the caulking tube to create an opening that’s no larger than the bead you would like to produce. Also, cut the tube at an angle, rather than straight across. A small, angled opening in the tube will produce the cleanest, easiest-to-control caulking bead.

Another simple trick is to keep the end of your caulking tube clean and free of dried caulking. To do that, fill your 5-gallon bucket with enough clean water so that you can hang the caulking gun from the edge of the bucket by its hook and have the end of the tube suspended in the water. That way you can easily transport and store the gun and tube while you’re working, without the tip ever drying out.

To apply the caulk, start at one end of the gap you’re trying to caulk, then pull the gun toward you as you gently squeeze the trigger. Getting a clean bead is a matter of the right combination of trigger pressure and gun speed, but it doesn’t take much to master the technique.

As you start to approach the end of the bead, let up on the trigger pressure, and as you come to the end, press the release button to relieve the pressure on the tube and stop the caulking flow. There’s often still going to be a slight flow of caulk out of the end of the tube even when you release the pressure, so have a piece of scrap cardboard available to set the gun on, or hang it back in the bucket and allow the excess to drip back in there.

There are different tools available for smoothing the fresh bead if necessary, but to be honest, most everyone, including the pros, still use their finger. You’ll probably want to be wearing gloves to avoid a lot of washing up afterward. Also, when running your finger along those joints, be really careful about picking up a splinter, or cutting yourself on nails or even the sharp edge of old paint.

Keep a damp rag with you at all times. It’s the only way to keep your hands, your equipment, and any adjacent surfaces clean. Rinse the rag often, because it will quickly begin to stiffen up as it gets caulking on it. You’ll also find that after a short time, rinsing won’t do much good any more, and that’s when it’s time to change both the rag and the water in your bucket. If you remember to do both, you’ll find that your entire caulking project runs a lot smoother, and everything stays a whole lot cleaner.

Remodeling and repair questions? Email Paul at paulbianchina@inman.com. All product reviews are based on the author’s actual testing of free review samples provided by the manufacturers.

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