It only takes a quick stroll through one of today’s massive home centers to see for yourself the rows upon rows of glues, mastics, epoxies and adhesives for every conceivable use. It’s definitely confusing, but here are some tips for breaking it all down into a few basic categories.
Craft and Woodworking Glues: Aliphatic resin (AR) adhesives are the common white and yellow glues used for any number of household applications. White glues bond wood, paper, leather and a number of other porous materials, while the yellow woodworker’s glues have additional additives to make them a little tougher for woodworking applications. These glues have a moderate open time (the amount of time you have for moving and aligning the pieces being glued before the glue sets up), and once aligned should be clamped until dry. Once cured, yellow glues form a tough bond that is typically as strong or stronger than the wood itself.
Instant Glue: Technically known as cyanoacrylate (CA) adhesive, instant glues are probably best know by the brand name Super Glue. CA adhesives dry almost instantly, and will work well on a wide variety of surfaces. There are now CA adhesives available with slower drying times and also with thicker consistencies for filling small gaps between materials. Follow the manufacturers instructions carefully, and have a bottle of compatible solvent available for freeing up the invariably stuck fingers.
Polyurethane Glue: Polyurethane glues such as Gorilla Glue can be used on a wide variety of materials with excellent results. They produce a very strong, waterproof bond, and have the ability to fill small gaps between materials. Polyurethane glues expand as they dry, so it’s very important that the pieces be clamped or blocked tightly to prevent movement during the curing process. Polyurethane glues are a very good, easy to use, all-purpose adhesive that will find a lot of uses around the house, but be sure and follow the manufacturer’s application instructions carefully.
Construction Adhesive: Construction adhesives come in tubes for use in any standard 10-ounce or 1-quart caulking gun — just snip off the end of the tube, puncture the inner seal, and it’s ready for use. Construction adhesives are tough, thick, water-resistant, and have a fairly long open time. They are the right choice for adhering subfloors to joists, paneling or drywall to studs, wood to masonry, and other heavy-duty job-site applications. If you want to use construction adhesive with pressure-treated wood, be sure the label says it is rated for that use.
Pressure-Sensitive Glue: Pressure-sensitive glues and adhesives bond on contact between surfaces, require no clamping, and have no real open time. There are a growing number of pressure-sensitive glues and adhesives on the market, and they can be used with a wide variety of materials. One of the most common pressure-sensitive adhesives is contact cement, which is applied to both surfaces and forms an instant, very strong bond as soon as the two pieces come into contact. The pieces must be properly aligned before pressing them together, so use a piece of wax paper or small wooden dowels to keep the pieces separate as you get them aligned. Other pressure-sensitive adhesives include double-face tapes, glue-sticks, and Glue Dots.
Epoxy: Epoxies are synthetic resins that can be used to adhere a variety of similar and dissimilar materials. Epoxies are very tough, waterproof, and extremely durable, and come in two parts that must be mixed together prior to application. Liquid epoxies are easiest to use where you have a hole to fill, such as cementing a bolt into a hole in a concrete floor. Simpson Strong-Tie and other manufacturers offer an easy to use epoxy “syringe,” consisting of two tubes of liquid with a twin plunger handle — press down on the handle, and the two liquids flow out of the tubes and into a common nozzle, where they are mixed and dispensed.
There are also putty-type epoxies, which come in stick form and work well for vertical and overhead applications. Simply cut an equal amount of putty off each stick, mix them together by rolling and kneading them in your hands, then place them in position.
Mastic: There are lots of different materials that fall under the general heading of mastic, which includes both adhesives such as tile-setting mastic, and sealants such as roofing mastic. In general, mastics are thick, sticky, premixed materials that are applied with a trowel or other tool. Mastics have a relatively long open time, are waterproof, bond very well to a variety of materials, and form a strong durable bond without clamping. When selecting a mastic adhesive, be sure and read the label to determine if it is specifically designed for bonding the two materials you’re working with, such as ceramic tile to concrete.
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