Silicone Caulking Basics
For caulking around bathroom and kitchen fixtures, nothing lasts longer or keeps out moisture better than silicone.
Synopsis: It’s not hard to make a mess with a tube of silicone caulk and a caulk gun — plenty of us do. This article, written by an experienced renovation contractor, explains how to apply this material so it goes where you want it to. Tips cover the simple tools used to shape a bead of caulk once it’s in place.
Sealing a bathroom fixture, kitchen fixture or ceramic tiles with silicone caulk is one of those small details that — done well — raises a job above an ordinary level. I don’t know how many times I’ve seen the effect of a good tiling job — and sometimes even a superior one — spoiled by sloppy caulking.
Proper silicone caulking accomplishes two things. It prevents water from finding its way into the gaps where two surfaces meet, with enough flexibility to maintain the integrity of the seal even if the materials shift a bit over time. And when the caulk is smooth and even, it helps to prevent the accumulation of dirt and mildew outside the seal, which helps to maintain the aesthetics of the job over time. A workmanlike job accomplishes the first purpose, but it requires more practice and care to accomplish the second.
Silicone caulk is the caulking of choice for ceramic tile, showers, tubs, sinks and other bathroom and kitchen fixtures. It costs more than latex caulk, but it lasts longer — up to 20 years. It’s a rubbery material with a tenacious grip, so it does a better job of stretching and flexing. Because it stretches without cracking or splitting, it does a better job than latex of sealing out water that inevitably accumulates next to kitchen and bath fixtures. Also, it has a wide temperature-application range and can withstand temperatures from below 0°F to about 400°F.
The drawbacks include silicone caulk’s finicky nature when it’s being tooled and its reluctance to adhere to painted surfaces, plastics or oily woods. Also, silicone caulking is generally not paintable.
Start with the right stuff
The basic caulking tool is, of course, a caulking gun, but even here a little care is needed. A gun that operates with ratchet action is no good for fine work. With ratchet action, you have to release the trigger and reach around to the back, grab the end of the rod and twist it to relieve pressure in the tube. In that time, it’s easy for excess material to squeeze out, and the action can cause the tip to jerk, which spoils the bead.
Instead, find the type with a (usually) hexagonal rod and no notches, which is released by pressing your thumb on a tab behind the handle. This type of caulk gun delivers caulk with a smoother flow, and the pressure can be released instantly so that you won’t have to take your eyes or your hands away from the work. (Tub and tile caulk in a squeeze tube works only on very small jobs. There’s just not enough caulk there to give a long and consistent bead.) Some caulk guns have a spout cutter that is incorporated in the handle, but I prefer to cut the spout cleanly with a sharp knife.
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