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Glue Choice

Question

Which glue should I use for which project or wood?— Bob Fuller

Answer

Al Breed replies: I am an animal glue user for the most part, so here is what I find best. Veneering—I use hot hide glue because it is reversible, fills the grain and can be hammered onto curved surfaces with no cauls. Joinery—Aside from big, long edge gluing like making a bench top, I use it for furniture construction because it is easy to clean up, is reversible and sets up fast in a dry environment making it good for rubbing in glue blocks. It’s as strong as any glue and will last for hundreds of years.

A word on “gap filling” glues—spend more time on your joinery.

Garrett Hack replies: Titebond #1 works for just about all woodworking applications. It’s similar to common white glue. Both bond in minutes, so if you need more working time to get things together, Titebond #3 is the glue to use. It’s also waterproof and has a brown glue line, better for darker woods. I’ve been using Gorilla Clear glue for challenging assemblies where I need a much longer working time (20 minutes) and lubrication to get tight joints together with no foam-out. Occasionally you might use epoxy for very oily woods (rosewood) or joints that need a bit of gap filling. And if you veneer or laminate, you’ll use a glue such as Unibond 800 with a long open time and rigid waterproof bond.

Elliot Savitzky replies: If you have a conversation with anyone that swears by hide glue, you will never want to use any other glue. It’s relatively cheap, easy to mix from powder and has a fairly long shelf life, but needs to be heated to around 140 degrees to work. The real advantage of hide glue is that it is totally reversible. Just apply heat and moisture and you can back out a tenon that has been glued into a mortise. Try doing that with a piece that has been glued with PVA. And there is no danger of leaving glue spots that the finish will not cover after glue-ups as it does not leave a stain. In fact, there is a great demonstration of the benefits of hide glue now available on our Guild YouTube channel by Jim Russell from a recent Period Furniture meeting. He shows how to mix it, what to use, how to glue-up veneer with a veneer hammer and how to trim the pieces—Hide Glue and Hammer Veneering with Jim Russell.

PVA glues, on the other hand, are really convenient in that all you have to do is open the cap and apply. You have to be careful to wipe up any squeeze-out during glue-ups. The major brand of PVA glues is Titebond (Original, II and III). The key differences between them are that Original is cheapest and has the shortest open time and is not particularly water-resistant. Titebond II has a slightly longer open time and is water-resistant. Titebond III has the longest open time and is waterproof. So, if you have a particularly complicated glue-up, use Titebond III to extend your open time to make sure all the parts fit well and the case is square. If water is an issue, then Titebond III is your option.

Another class of glue is polyurethane. I despise it mostly because any squeeze out is almost impossible to get rid of.

CA glue (cyanoacrylate) creates an almost instant bond, especially if you spray it with an activator to hasten the process. Use this when you need to bond something really fast before it falls off and when you are bonding things other than wood.

Urea Formaldehyde glue, also known as Plastic Resin glue is used for face and edge gluing and especially with wood veneers in a vacuum press. The resin needs to be mixed with water and a lot of care needs to be exercised as you don’t want to inhale any of the resin dust so a filtered mask is mandatory. This glue is sold under the name Unibond 800 among others. Unibond One is a one-part PVA pre-mixed version that is excellent for veneering and vacuum bags and has a longer open time. However, I have been very successful in using Titebond III for veneering using a vacuum bag. But of course, going back to hide glue, you really don’t need any vacuum bags. Titebond has also gotten into the veneering market by introducing a Cold Press glue, which has a fast (15 sec) set time and 24 hours to fully cure and has no harmful vapors.

The last and very common glue is Epoxy. Mixed in two parts (resin and hardener) this is what you want to use if you never want anything to come apart. It is used for different types of materials (plastic, wood, metal) and dries clear for finishing.

Ted Blachly replies: In my work I use Titebond Original, Titebond III, Epotek 730, Unibond 800, West System-G Flex 655, Cyanoacrylate, 5 minute epoxy, Gorilla glue, hot hide glue and Elmers white glue. It depends on what you need to do.

There can be four or five different glues or epoxies used in one piece. An example might be—Unibond 800 for bent lamination assemblies. Epotek 730 for a case where 60 or 70 joints have to be coated and assembled in one session. It gives about forty minutes for a careful assembly of all the parts at once. Titebond would be out of the question here but I’ll use it for edge to edge joints and putting together the dovetail drawers. Cyanoacrylate might be mixed with sawdust to patch minor tear outs or wood defects, Elmers white glue would be used for leather to wood joints

Tags: Glue