What glue is best, or what glue should I use? The answer is not always simply “this or that,” but the following might help!
White and Yellow Glue
In general, these glues are all polyvinyl acetate adhesives or PVAs for short. White glues have been around longer than their yellow cousins, take a little longer to set up, and are a little more flexible. Yellow glues are more moisture resistant, have a faster setup/curing time, and are not as flexible. Both require substantial clamping pressure to properly hold.
PVAs used to be considered for indoor use only, but now you get them in both moisture resistant and waterproof formulas, making them suitable for all sorts of outdoor projects. Be sure to read the label before use to make sure you have the right glue for the job. PVAs are the workhorses of the Woodworking community.
Hide Glue
Hide Glue is an animal glue or protein colloid glue formed through hydrolysis of the collagen from skins, bones and other tissues. First written procedure for making Hide Glue is from around 2000 BC, but there is evidence of usage by the Neanderthals. Hide Glue is still the choice for many woodworkers and luthiers because it doesn’t creep, is crystal clear and is reversible.
Hide Glue can come dry as pearls or flakes, which are dissolved in heated water and kept warm while using the glue. Different gram strengths are associated with dry glue for different purposes. The 192 gram is good for marquetry, veneering and beginners; the 251 gram is a good all-purpose woodworking glue; and the 315 gram is for small repairs and lutherie.
Hide Glue also comes in liquid form, which is a convenience for woodworkers. Purists think it not equal to the dry form, but several companies make the liquefied version.
Epoxy
Epoxy is a two-part glue requiring mixing prior to application. The two parts are the Resin and a Hardener. Hardener formulations can vary to increase or decrease the speed with which Epoxy sets up. It can be as fast as 5 minutes or as long as a few hours to develop strength, but generally all Epoxy requires 24 hours to achieve full strength. Epoxy is not dependent on clamping pressure to insure adhesion so light clamping pressure is best. Epoxy is waterproof and is great for structural repairs to furniture joints.
CA Glue (Super Glue)
Short for Cyanoacrylate, CA comes in a variety of curing speeds and thicknesses, from a thin liquid to a gel. It can be clear or black and have additives that can affect curing speed and durability, such as a rubber additive to make it more shock resistant. CA glues have a relatively short shelf life of approximately 1 year unopened and much shorter after opening. Usable life of both can be extended if stored in a refrigerator. Generally, these glues are used for small repairs on surfaces and joints.
Polyurethane Glue
Liquid polyurethane is 100% solid glue that is activated by moisture on the surface of wood and in the air. Generally, it is applied lightly to one side of the joint and then a clamp is applied. It’s waterproof so it’s good for use on Indoor and outdoor projects. Gloves should be used because it will stain skin.
