In this post, Frank discusses the historical uses of hide glue, it’s pro’s and cons and how it compares to yellow glue. He also discusses the proper way to prepare and apply the glue on projects using traditional joinery techniques.
Hi. My name is Frank Strazza, with the Heritage School of Woodworking. In this video I want to try to unlock some of the mysteries about hide glue.
I’ve been using hide glue more and more for my furniture making. My first introduction to hide glue was in violin-making, which is one of the traditional glues used for building violins. But my take on hide glue is, one of the reasons why we have the great violins of the past is because they were glued with hide glue. And the same with antiques, as well.
The reason why we have antiques is because they were glued with hide glue. Well, why? Well, hide glue is reversible. So if you make a mistake, you can actually fix it. And it doesn’t matter how old the glue is, you can actually take the joint apart, using heat, and a little bit of moisture, and such.
So I’ve found more advantages to using hide glue. One of the great advantages to using hide glue is the fact that the glue will actually lubricate the joints. So I can make my joinery– whether it be a dovetail or a tenon, I can make it much tighter, and the glue will actually lubricate that joint.
Whereas if you’re using yellow glue, yellow glue actually seizes the joint. If you’ve ever dry-fit a joint together, and then you go to glue it up with yellow glue, and it doesn’t always seem to go the same, go together as well using yellow glue– well, hide glue, it’ll go together even better than dry-fitting.
So I want to show you a little bit about how I mix it up. I’ve got about five pounds. Actually, I’ve used quite a bit. But I bought five pounds here from Eugene Thordahl, bought in bulk. You can get this granular glue from Tools for Working Wood, Woodcraft– a lot of these woodworking suppliers sell the granular glue. So I’ve got it here.
And this is 192 gram strength, which is fairly typical for furniture making and such. There’s other gram strengths. In violin making we use a 315, which tacks faster, but it’s a little stronger. But this stuff is plenty strong.
What I usually do is, I’ll just take a measuring cup and put this in a spice jar like this. Truthfully, I really don’t measure that much in the glue. In this case, I’m not even really measuring the glue. I’m just scooping it into this container here. And I fill it up about halfway or so.
And then what I want to do is pour cold water over this. And I want the cold water to absorb all of the glue. So I pour the water until it just comes over the surface of that glue. And you’ll notice that glue will absorb all of that water. And that’s what we want.
You can see down there, there’s still some dry granulars of that glue. We want that to totally absorb. And once that does, what I can do is take something, stir it up, try to make sure it gets all the way down in there. Sometimes, if you have a wad of the dry glue, the water won’t get all the way down to the bottom. It’s important that all of that glue is soaked up by the water. You can see there– now it’s this mushy kind of paste, if you will.
And at that point, I’m going to put it into a glue pot. And there’s different glue pots available. This is one that you can buy. It’s fairly easily obtainable. But this is just a standard glue pot. But what I’ve done differently here is I put water inside this. This is a double boiler. This heats it. And what some folks will do is, they’ll just put the glue right inside this part right here.
But what I’m going to do is put water right inside of here. And then I put this spice container here– which is plastic, by the way– which is important. I like to use plastic because the glue will actually chip the glass. You can use glass, but glue can chip it, and it’s a little bit harder to clean it with the glass. So I put the plastic container in here. The other advantage to using this plastic container is the fact that it has a lid– which, if you don’t have a lid on hide glue, it will dry out.
So I’ll just keep that in there for probably about 15 minutes or until it cooks. The longer it cooks, the better. It might be 30 minutes or so before it’s good and well-cooked.
OK. I want to show you the consistency of the glue, once it’s been cooked for a little while here, and it’s stirring up nicely. But one of the tests is, I can take this, and if it runs off the brush like this without– just a nice, continuous run right off of the brush. That’s what we want. That’s a nice consistency of good, hot glue.
Now one of the disadvantages to hide glue is that it can tend to gel up fairly fast. So it’s helpful to work in a heated shop or to even preheat the joint. Sometimes I’ll use a heat gun, just to preheat the joints.
Another way to extend the working time of the glue is to add some urea. And this is just some urea, 46-0-0. I actually found this on Amazon. Five pounds of it is, like, $10 or something. So this will last me probably two lifetimes. So if you need any urea, you know where to call.
Now the key here is not to add too much of this. What I’m going to do is add about a half a teaspoon to about a quarter of a cup of glue. That’s what I’ve found works pretty well. On Eugene Thordahl’s website he has a chart that has some of the descriptions of how much urea to add to the glue to extend the work.
So I just take a half a teaspoon here and just pour that right into there. And what happens is, as the glue is cooked and warm, these things will just dissolve in the hot glue. And once it’s dissolved well, you just stir it up well, and that will extend the working time of the glue.
OK. One of the great things about hide glue is, unlike any other glue, you can actually reuse your waste glue. That is, if you have some squeeze-out, excess glue coming out of a joint– look at this. So you can come right over here and just take that. This is still kind of in a gel-like substance here. And you just put it right back in that glue bottle, and you can reuse, recycle, the glue. So no waste here. Look at this. I can just take all of this excess glue and put it right back in there.
And it’s easy to clean this stuff up. It just comes right off. But it’s super strong. There was a fellow that works at the Smithsonian as a conservator, and he said that hide glue was just about as strong as epoxy. It’s hard to believe, isn’t it?
But the downside to hide glue– there is a downside, and that is that high heat and moisture will break down the glue. But hey, there’s been pieces of furniture that were made hundreds of years ago. They’re still held together with hide glue.
And if it needs to be repaired, it’s easy to repair. You can just reconstitute the glue, just put the fresh layer of glue right over it. It will reconstitute itself, and you can repair your joint.
So go get some hide glue. Try it. I think you’ll find, as I have, that you really enjoy using it.