Stick and Seal: The Basics of Adhesives, Glue and Caulk
It'd be great if there was one caulk or one adhesive that did it all. But for nearly every job there is a specific caulk, adhesive or glue. And while they often are thought of together, they can't always be found together. You'll find them distributed throughout a store and grouped together by application.
For example, look near the paint aisle and you'll find the caulk section. Head over to tile and flooring, roofing and masonry, and there will be a nice selection there as well. The location of glue and other adhesives also range widely, but often occupy a smaller section near the paint, with some construction adhesives found next to the caulk in a completely different aisle.
But there is a method to the madness, and it just takes a little savvy to make sense of it all.
Seal the Deal With Caulk
We all want a “tight” house with no drafts or leaks so we save money on energy bills and keep out moisture to avoid water damage and mold. We also want our water-laden areas — the kitchen and bathroom — to keep water where it belongs.
For bathrooms you'll need caulk labeled for tub and tile. These are formulated for high-moisture areas and resist mold and mildew. Within this type of caulk are several variations, included sanded ceramic-tile caulk, which is available in colors to match the color of your grout so you're not limited to bright white or clear caulk.
Caulk for use around doors, windows and molding will be clearly marked. Generally, the same caulk can be used for all of these applications. Make sure that the product you get is labeled as paintable because paint will not adhere properly to certain types of caulk — it will bead up like oil trying to mix with water. For outdoor applications, select caulk rated for exterior use. Most often these will be either silicone-based or an acrylic blend with silicone added. Image 1 shows three varieties of caulk including: tub and tile; paintable acrylic blend window, door and molding; and silicone window, door and molding.
Although it can be tempting, caulk shouldn't be used as a filler. For gaps larger than 1/4 inch, you'll need to use a spray foam or backer rod to fill larger gaps, and then follow up with caulk. Backer rod is usually found with weather stripping.
Most caulk comes in a tube that requires a caulk gun, which consists of a “trigger” that drives a plunger pushing the caulk through the tube toward the tip. Caulk guns are a must-have and range from just a few dollars to $12 or more. They all perform the same function, so there's no point in buying the most-expensive caulk gun unless you're a pro. Your best bet is a midrange gun at about $6. Some of the cheaper ones — less than $3 — can stick and have to be taken apart and reassembled frequently, which is not something you want to do in the middle of a job.
After you've applied a bead of caulk, simply use your finger followed by a damp paper towel to smooth it out. If that's a bit messy for your liking, many spreading tools are available.
Caps and Applicators
Some tubes of caulk will come with a cap. If not, a great trick for capping an open tube of caulk is screwing on a wire connector onto the tip. Connectors are threaded so they will grab onto the tip and stay in place.
Caulk manufacturers also make smaller tubes of caulk that don't require a caulk gun. They're a lot like a tube of toothpaste. Many of these come with tips that can be screwed on and removed, which makes cleaning much easier.
Getting a Grip With Adhesives and Glue
The white glue we used in school always comes to mind when we think of the sticky stuff, but other than making construction-paper art, it's not very practical in DIY situations.
Not all wood glues are the same. Titebond has three main varieties and they are pretty easy to identify by their label. Plain Titebond is the typical wood glue you'd want to use for most woodworking and carpentry jobs. Titebond II can be as well, but it also offers waterproof/exterior uses. Titebond III, which some woodworkers simply use as a default glue, has good exterior capabilities and has a longer “open” time than the other Titebond glues. Open time refers to how long before a glue starts setting. This is important if you're working on project that requires a lot of setup or assembly prior to being clamped.
When using wood glue, make sure to apply a solid bead and spread it evenly using an acid brush. Apply enough so that the mating surfaces are thoroughly covered.
Construction adhesives, such as Loctite and Liquid Nails brands are best for large projects like laminating beams. They’re also good for smaller jobs like attaching trim, molding and paneling, especially if you don't want to use fasteners. They're not all quick-setting, so you'll need to check the label.
Liquid Nails can be used in multiple applications and with multiple materials. It's perfect for a wide variety of jobs, everything from repairing vinyl flooring to shoe repair. And one of the best parts is that it dries clear and can be cleaned up with water.
In the last few years polyurethane glues, such as Gorilla Glue, have become popular for a lot of uses, primarily repair jobs. The product requires the bonding surfaces to be dampened to activate the adhesive. This process creates a foam that penetrates and fills the bonding surfaces. But be careful: Not knowing how much foam will be created after the initial squeeze often causes DIYers to use too much and ultimately create a big mess.
Epoxies generally come in two parts that need to be mixed to activate. These are best for heavy-duty and permanent uses including large outdoor projects and connections that have a weak joint.
Spray adhesives are good for attaching fabrics and vinyl sheets to large surface areas. For example, they can be used to attach felt to the bottom a wood box or checkerboard.
Hot glue is great for a lot of craft projects, but it can also be used to temporarily hold project parts together while the permanent glue sets up — especially in situations where clamps are hard to use. Hot glue will not provide a good solid adhesive on all surfaces and shouldn't be relied on for quality holding power.