While wood is the central material for any furniture building project, the glue you use is definitely second. Glue has been a vital part of furniture making since ancient times. This can be seen in ancient Egyptian furniture, as well as pieces that were constructed by European renaissance craftsmen. While the need for glue in furniture making has not changed over the years, modern technology has created a series of specialty glue each designed for a specific purpose.
What the Heck Is Hide Glue?
Some of the earliest glues used were called hide glue. Hide glue is made from animal products and is extremely useful for difficult joints or areas that may need to be disassembled. Because hide glue will release its bond when introduced to heat and humidity, it is perfect for separating pieces without causing damage. Because hide glue cures slowly, it is also the right glue to use on areas that require a long time to assemble. The problem with hide glue is that it is affected by heat and humidity; two of the elements you will want your furniture to withstand. Thanks to modern technology, there are other options available to us.
What about Epoxy and Polyurethane Adhesive?
Among the most durable type of adhesive available, two-part epoxy is at the top of the list. If you are looking for the most water resistant adhesive available, epoxy is the best choice. There are however, several problems associated with using two part epoxy. The first problem is that it is messy to use. You need to make sure that the two parts are mixed evenly before application. Then you need to apply it to your material. This is definitely less convenient than using an adhesive straight out of a single bottle. The second issue is that epoxy is toxic. Make sure that you wear protective gloves and a respirator to protect yourself from chemical exposure. Because of these issues, epoxy is not the best choice for everyday use.
One of the newer options mesaproducts available to woodworkers is polyurethane glue, which is supposed to be suitable for any gluing application. The odd feature of this type of glue is that actually cures by being exposed to moisture. This makes it perfect for use on items that will require maximum water resistance. As the polyurethane glue dries, it actually expands. While this will provide a very solid joint, the glue will expand outside of the joint and on to the surface of your product. This will require additional sanding, but you will achieve a nice, solid joint.
When Should You Use White or Yellow Glue?
White and yellow glue, as they are commonly called, are actually polyvinyl acetate adhesives. White glue is generally a good adhesive to use on most porous materials, while yellow glue is designed to be used for interior projects. These types glue have not been designed for a water resistant bond, so do not use them for exterior projects. There are however specially formulated types of yellow glue that have been designed for water resistance. This type of glue will cure through a chemical reaction and not evaporation.
The best choice for woodworking beginner is yellow glue, also known as aliphatic resin glue. This glue is easy to use, is not toxic and cleans up with water. It is also easy to sand, will not “clog up” your sandpaper with residue and leaves an almost invisible glue line. Like all glues, there is a shelf life of approximately a year. Do not use this type of glue if it starts to smell sour or becomes thick or stringy. This means the glue is past its prime and should be disposed of properly.