Nice job.

Heating hide glue isn't that difficult. You can buy an electric glue pot from places like StewMac, but they're pretty expensive. A cheaper route is to do what I did. I think I spent $50 to put together an electic glue pot of my own, including the cost of the glue. I bought Brooklyn Tool & Craft 192-gram strength, which is what is recommended for musical instruments. It comes in a 1-lb. bag, which is enough to last me a long, long time.

I bought a Sunbeam Electric Hot Pot that can be used as a double-boiler. I also bought a kitchen thermometer. I heat my hide glue in a coffee cup. I modified the top of the soup pot by inserting a small aluminum tube I bought at the local hobby store. This allows me to measure the temperature of the glue without the thermometer resting on the bottom of the cup.

I drilled another hole in the top of the soup pot that I use to dip the acid brush into the glue.

This setup works well because it keeps the glue at the right temperature which allows plenty of working time without the glue cooling down too much. Because the glue cup is kept inside a warm, moist environment it never skins over.

Dan

Most glues form a simple mechanical bond with the parts being joined. Hot hide glue (HHG) forms a chemical bond. What this means is that you don't need to sand the joints to rough up to surface.

To use HHG, you simply add water to the glue granules, then heat it to 150 degrees.

While it's in the liquid state, you brush a thin layer onto each of the two sides of the joint, then squeeze or clamp the two pieces together until the glue takes a set. It only takes a few minutes for this to happen. Once the glue takes a set, it will continue to shrink and draw the joint together. After it hardens, you can easily clean up any excess with water.

One of the major differences between HHG and other glues like carpenter's glue (aliphatic resin) and epoxy is that hide glue doesn't soften when it gets heated. This prevents creep. If you leave a guitar with carpenter's glue or epoxy in an area where it will get hot, these glues will soften which will allow the glue joint to come undone.

HHG doesn't creep when it gets hot. The only other glue I've used that has this characteristic is cyanoacrylate. (CA, or super glue)

One of the desirable features of HHG is that joints can be easily separated using only steam. So, if you make a mistake and the joint isn't quite right, you can use steam to soften the glue and reset the joint.

The classic example of this in luthiering is using hide glue for neck to body joint. This allows for relatively easy neck resets. Not as easy as a bolt-on neck, but a lot easier than necks glued on with aliphatic resin or epoxy. Interestingly, another characteristic of CA is that it dissolves when it gets wet. It doesn't happen as fast as HHG, but it will happen. Technically, the CA doesn't dissolve. It just loses its grip when the underlying material becomes wet. Separating a CA glue joint on a guitar requires that the wood would need to get a wet for quite a while, which is not a good thing for guitars.

The downside to HHG is that it has a fairly short working time when compared to aliphatic resin or epoxy. As the glue cools, it starts to harden and resists flowing out of the glue joint. Once the HHG starts to gel, it becomes increasingly difficult to get it to squeeze out and form a tight glue joint.

You can extend the working time by preheating the joints so the glue doesn't cool as quickly as it would when you brush the hot glue onto a cold surface. I used HHG and the glue pot in the pics to fix a guitar that had a broken headstock. I used a heat gun and an IR thermometer to preheat the two sides of the joint to 150 degrees before brushing on the HHG.

Another trick is to make a thinned batch of HHG, called sizing, then brush it onto the joints so it flows into the cracks and crevices and then let it dry. When you're ready to glue the pieces, you brush on another thin layer of HHG to reactivate the sizing and squeeze the joint together.

Here's a couple of pics of the headstock repair I did. I let the glue joint dry for a couple of weeks then filled in the missing finish with ZPoxy. To match the color of the original finish I added dry pigment before I mixed the two parts of the epoxy.  I wanted to try my hand a luthiering and HHG, so I found a broken guitar on eBay and used it for experimentation. In addition to fixing the neck and repairing the finish, I also made the bone nut. It's not perfect, but I learned a lot and the guitar plays great.

Before:

After:

Interesting stuff Dan, but now I'm beginning to wonder if maybe you're Adam Savage's (Myth Busters) smarter brother!

Have you C4'd any Lyrachord® bowls into oblivion... or made any acoustic guitars entirely out of duct tape??   

btw - I've heard that vegan is an ancient Mayan word that means lousy hunter.  

Ok!!! I finally finished this wonderful Ovation. It's been done for quite some time, but I just put the headstock logo on. The only real thing holding me back was that I ran out of ink on my printer. Here is the final shot!!

It looks better in real life. I used bounce flash, which makes the top edges look white, but normally you don't really notice the lines.

I think it looks pretty good. not perfect like the real one, but pretty good!