Until recently, I had a rather elementary understanding of adhesives. (Elementary in the sense that, like a third grader, I was overly fond of peeling dried Elmer's off my fingertips.) But woodworkers aren't into children's school supplies, opting instead for serious-sounding, grown-up glues like aliphatic resin emulsion.
Selecting an appropriate adhesive may seem nonessential, but it can actually make or (literally) break a project. Furniture makers take their glue seriously, and rightfully so — without it, most joinery simply wouldn't handle the pressures of everyday life. Good wood glues are designed to be even stronger than the woods they are applied to — meaning if a joint were to break, the wood, not the adhesive, would be to blame.
And while glue might turn a cursory mistake into a more permanent position, that's no reason to shy away from it. If you are prepared with some decent clamps (Bessey and Wetzler make the best) and a handy assistant when necessary, you'll be just fine. Once you've identified the best adhesive for the job, you can usually just stick to the directions on the bottle — that's if you don't get stuck to the directions on the bottle.
• Yellow glue – Whatever you call it (polyvinyl acetate, aliphatic resin emulsion or simply, yellow carpenter's glue), this stuff is the closest thing there is to the perfect wood adhesive. It's cheap, non-toxic, easy to find in hardware stores and works without fail. It's used in everything from case construction to veneering — however it does dry lightening fast, leaving you with very little wiggle room. Try Titebond I or Titebond III if your piece will be exposed to moisture.
• Epoxy – Epoxy is usually sold as a two-part solution. Add equal parts resin and hardener and you're left with a smelly, toxic goo that's great at filling loose joints and killing your sensory system. On one hand, it's waterproof and has a long set time, allowing you to adjust your glue joints until they are perfectly flush and square. On the other, it's mighty expensive and dangerous to touch and inhale. Your sense of smell is kinda swell, so wear a mask and gloves!
• Polyurethane glue - Polyurethane glue is relatively new to these shores, having been introduced in the U.S. less than ten years ago under the Gorilla Glue brand. Everyone makes the stuff now and for good reason: it's very strong, water-resistant and takes stains fairly well. But despite what they advertise, nothing fills gaps like epoxy.
• Hide glue - Made by boiling the connective tissue of animals, hide glue dates back to Ancient Egypt. With the advent of the adhesives above, it has become a specialty glue primarily used by instrument makers. Applying heat will loosen the joint, allowing for delicate repairs to be made. Most hide glues must be applied hot and smell like burning hair.
Best of luck with all your glue-ups!
Johnny is currently blogging his experience as a student and amateur woodworker. You can keep track of his projects on his blog, Woodlearner.