By Paul Bianchina
Remember when the local hardware store stocked two or three types of adhesives that seemed to do just about everything? New technology, as well as government restrictions on the ingredients of many products, has created a whole world of specialized adhesives for virtually any application, and they work great as long as you know which ones to use.
Wood
For working with wood, you have a very wide choice of products. One of the most common is aliphatic resin (AR) adhesive, more commonly known as yellow woodworker's glue. AR adhesives have a thick, rather creamy consistency, and have been used by woodworkers and carpenters for decades. Two of the most widely recognized brands are Elmer's Glue and Franklin's Titebond, and both of these companies have made continual strides toward refining and improving their product's performance.
Unless otherwise stated, AR adhesives are for interior use only. Franklin offers Titebond II, which is weatherproof and safe for most outdoor uses. Elmer's has Weather-Tite, which is not only is fine for outdoor use, it's also in a thicker gel formula that reduces running and dripping and dries to a cleaner, less noticeable line. In addition to wood, AR adhesives can be used on paper, cloth and a variety of other porous surfaces. The adhesives have a long shelf life as long as they are tightly capped and protected from freezing.
Developed in Europe and relatively new on the American scene are polyurethane glues, which compete favorably with the older, two-part epoxy adhesives. Polyurethane adhesives - Excel and Gorilla Glue are two common brands - are premixed liquid adhesives that are fine for exterior or interior use. Once applied to the wood, they have a longer setup time than AR glue, as much as 15 to 20 minutes, which gives you more time for positioning the glued pieces correctly. Polyurethane adhesives react with the moisture in the wood and the air to begin a catalyst process somewhat similar to epoxy. As the glue dries, it begins to foam slightly; the dried foam scrapes or sands off exposed surfaces very easily. The only drawback is that polyurethane glues have a shelf life of only about one year.
For general construction applications, your best bet is construction adhesive. Sold in two different sizes of tubes for use in caulking guns, construction adhesive is a thick, sticky bead that fills gaps and adheres well to a variety of surfaces. It is waterproof and can be used on wood, masonry, drywall, ceramic tile and many other materials. Some types of construction adhesive won't work well on pressure-treated lumber, so if that's your intended use, be sure to check the label.
Masonry
For anchoring bolts and other materials to masonry, including concrete, stone, brick and other similar materials, epoxy is the best product. Epoxies come in a two-part formula of catalyst and hardener, and must be mixed together in equal portions to form an adhesive. There are a variety of types of epoxies, all of which are very strong and durable. Most have a very long shelf life as long as the components are kept separated; once they're mixed, an irreversible chemical reaction begins and you have only a limited time to use them.
Epoxies take three basic forms: liquid, putty and paste-like. Liquid epoxies are easiest to use where you have a hole to file, such as cementing a bolt into a hole in a concrete floor. The two components are mixed in a cup or other container, then poured into place. Simpson Strong-Tie, a leading manufacturer of joist anchors and other construction fastening products, offers an easy to use epoxy "syringe." It consists 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.
Another type of liquid epoxy comes in a glass tube, and is designed for anchoring bolts, rebar and other similar applications. Simply drill a hole, insert the tube in the hole, then hammer in the bolt; insertion of the bolt breaks the tube and allows the two components to mix and harden.
Putty-type epoxies come as two separate sticks. Simply cut an equal length off each stick, knead them together in your hands, and then place them in position. The putty works well for vertical and overhead applications, and it's easy to measure and mix only as much as you need.
Multi-Surface Glues
One of the most popular glues around the house is cyanoacrylate (CA) adhesive, best know by the brand name Super Glue. CA adhesives dry almost instantly - as anyone who's stuck their fingers together can attest - and work well on a wide variety of surfaces. As their popularity has increased, you'll find a wider variety of products and applications available, including adhesives for both porous and non-porous materials, and adhesives with more gap-filling capability than the thinner, first-generation CA adhesives had.
Another favorite for secure adhesion on a variety of surfaces is contact cement. Contact cement is applied to both of the surfaces being joined, then allowed to dry. The two glued surfaces are then brought into contact with each other, and the bond is instant and very strong. Contact adhesive is one of the best materials for gluing large flat surfaces such as plywood, plastic laminate, particleboard and other similar materials. Contact cement is somewhat sticky and messy to apply, and some types have a fairly strong odor and must be used with adequate ventilation. Both surfaces must fit well and be ready to be glued - once the two glued-up pieces contact each other, there's no turning back.
All of the above adhesives are available in a variety of sizes and price ranges from hardware and lumber stores, woodworking stores, home centers and other retailers.
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