2-Part Epoxy Glues
Source: Tools & Materials
Believe it or not there are some definite tricks to gluing parts of the guitar correctly. If you get too much glue on your wood guitar parts, it will at a minimum, give you a messy cleanup chore and possibly a poorly glued or structurally insufficient joint.
Glue is intended to act as only a very thin film that will hold the two pieces of wood together. In softer woods, there will be some penetration into the wood fibers and the adhesion actually extends into the wood in those instances. This does happen to a smaller degree with harder woods as well.
How Much Is Enough?
The norm usually means too much glue is applied to the joint. The person doing the gluing, figures that if a little is good, than more should be better. That is far from the truth. The goal is to get the quantity of glue perfect. Follow these tip for good joint results.
Titebond II or III:
The best way to apply Titebond is to place a bit of glue in a dish or on a piece of waxed paper and apply it with a very small stiff brush. Usually these can be the tin-handled brushes you can pickup in the hardware store. Spread it with care not to get any on another part of the wood than the joint (yeah sure, right). OK – try to.
Make sure you apply glue to all surfaces that are to be glued together.
Now we want to make sure the glue film is spread evenly over both pieces of wood. This is most easily accomplished by rubbing the two pieces back and forth until you can feel a bit of resistance – that means you have the correct amount of glue in the joint.
Titebond cleanup is really quite easy as long as you clean it at the right time. Your window of opportunity is not that large so be very attentive to the glued area and test it constantly. Eventually you will know exactly when to return to the wood to easily peel off the glue. You know you have it right when the excess glue comes off like putty with no liquid squeezing out the the squeeze-out and also, also it is not too dry that it has to be chipped off.
5 Minute 2-Part Epoxy:
The biggest trick with the 2 part epoxies is to get the quantity of the resin and the hardener exactly at 50/50. If you get too much resin the glue won’t setup properly. If you have too much hardener the glue joint won’t be as strong as it should be and will be brittle.
Also be sure to stir the two parts REALLY well. You can tell if you have it stirred well enough by the color of the mixture. It will turn a whitish-creme color. Also if you mix your epoxy in a small plastic or paper cup, you will be able to feel the glue heating as it is going through the chemical reaction of setting up.
With 2-Part Epoxy, do not glue too much or too many pieces at one time. You actually may have a bit more than 5 minutes to work with it, but not much more.
To apply the Epoxy I usually keep some small pieces of maple veneer around for this purpose. Dip it into the mixture and slowly spread it on the joint. Now take the edge of the veneer (the edge should be cut square like a knife edge) and slowly spread the glue over the wood surface. It will glide just like a trowel and you will find the glue will go a really long ways.
As with the Titebond Glue, make sure the glue film is spread evenly over both pieces of wood. This is most easily accomplished by rubbing the two pieces back and forth until you can feel a bit of resistance – that means you have the correct amount of glue in the joint.
Epoxy cleanup is a bit more tedious than the water-based glues. Once it starts to get stiff you can get most of it off with a very sharp chisel. There will still be a residue left on the wood after this and you will have to have a lacquer thinner-soaked rag handy to do the final cleanup. Sight down the wood as you look into a light source and you can see any residue left because it will be shiny.
Additional Tips:
The smoother you make the joints of your wood that is to be glued, the less glue you will need to use.
If you are gluing exotic woods, be sure to use acetone to clean off the wood to be glued. The use of rubber gloves and a respirator is manditory to protect your hands and lungs. Rub with an acetone soaked rag until no more color comes from the wood. You will find this a particular problem for any of the Rosewoods, Koa, Cocobolo and many more.
Slow Set 2-Part Epoxy:
The only difference you will find with the slow set epoxy is the setup time you have available. It is extended to at least 30 minutes with full bond strength at 8 hours. All other things we talked about with the 5-minute Epoxy apply to the slow set.
Tags: gluing tips for guitars, guitar assembly, guitar making materials, how to make a guitar
