A Simple Hot Hide Glue Setup
Hide glue is one of my favorite glues, and one I consider almost perfect for many woodworking joints. It works easy, can fill gaps, leaves a clear line, mixes with sawdust to accept most wood stains and dies - and it doesn't "stain" the wood like yellow glue can. That's where glue-soaked wood won't accept stain and you get those blotchy areas around glue joints if you missed a spot when cleaning up the glue joint. It's also simply the best glue for dovetails and inlay, and is also used with traditional veneering methods.
Speaking of clean up, hide glue cleans up so much easier than *any* other glue - just scrape the excess off when it dries - and for the tools, hot water removed it, or a trip to the dishwasher will take care of it if it's dishwasher safe. It's also a reversible glue, simply by adding heat and/or steam. It's time-tested, being possibly the oldest glue still in use today. It's environmentally friendly - no nasty toxins or chemicals to pollute our precious Earth.
Some use the ready-mixed hide glue off of the shelf - but this glue has a few drawbacks. It uses a "urea" or some such to make the glue more stable at room temperature, and also to extend the glue's shelf life up to something like 6 months... but that includes the time it sits on the shelf, and these products effect the strength of the glue bond as well. In the end, hot hide glue is still the champion woodworker's glue.
So why isn't it used more? Good question. Perhaps one of the strikes against it is the requirement of a double boiler, which isn't cheap. Another is the fear of it going bad - hide glue has a short shelf life, after all. Well, I'm going to try and address both of those requirements to see if I can help out the cause of hot hide glue for the masses.
An Inexpensive Double Boiler.
I'll admit I don't use hide glue every day... I usually only do a project or two a year with it. Buying a full fledged double boiler has always seemed a bit too expensive for my tastes... and I usually don't need all that much glue at a time. A cheap and simple solution is to pick up a Rival "Hot Pot Express", available through Amazon or Sears, as well as Rival's own web site at the time of this writing for $12.99 plus shipping. Next, a standard meat thermometer that can be used to measure water temps in the pot, a small tapered jar (mine is a kid's Welch's jelly jar) that can be used to hold the glue, and a shop-made lid to hold the whole rigmarole in place:
Fill the boiler with water, and heat it to about 145-150 degrees. That's not so hot you can't touch it, but hot enough to melt the glue. To prepare the hide glue, mix equal parts of water and hide glue granules into the jelly jar, and place the jar into the special made lid, stirring occasionally. I use a double shot glass (shown in the photo above) to measure out the amounts needed - my jelly jar will hold exactly 2 double shots each of hide glue and water:
As the glue heats up, the granule begin to dissolve into the water, into a syrupy texture. Don't overheat the glue, as it will break down (essentially cook) and no longer bond to the substrate. Once the glue has fully dissolved, it's ready to use. Here, you can see the granules are not quite completely dissolved, but are getting very close:
I find using a cheap bristle brush the most effective way of spreading the glue, going directly from the jar in the boiler (which I keep at one end of the workbench) to the work being glued.
It's often recommended that you make no more than a week's worth of glue at a time, and that you refrigerate it after the work day is done. If that's all you need to do, then you can simply take the jar and put it directly in the fridge, and grab it the next morning when you head out to the shop (unless you are lucky enough to have a shop fridge).
Keeping the Glue Longer Than a Week
That's what I generally do for a weekend's worth of work. But I have a bit of an issue - sometimes I need to keep the glue good for longer than a week - sometimes even two or three. There's a simple solution - freeze it. Freezing hide glue allows you to keep it fresh almost indefinitely. One luthier makes a batch of hide glue and freezes it into ice cube trays, and just pops a cube out as he needs it (see Frank Ford's site, FRETS.com, which is a wonderful repository of knowledge!). Another option is to pick up some squeeze bottles such as these, and transfer the glue to it, then just toss it into the freezer:
I picked a ton of these squeeze bottles up from American Science & Surplus for next to nothing. The beauty of it is, next time you need some glue, you just take the squeeze bottle out of the freezer, and toss it into your double boiler. It give you a handy dispenser, and when you are finished for the day, you can put the bottle back in the fridge for the next days work.
Hide glue will only stand one or maybe two freeze/thaw cycle before it begins to break down (just like food!) and will not bond as well. But it's a great way to extend the useful life of the glue, letting you keep it without wasting it until the next weekend you have available to work with it.
Hope this was useful information.