Hide Glue Preparation

Hide Glue Preparation (Piano Tuning and Repair)

Welcome to our Series on Piano Tuning and Repair.

Hot Hide Glue is traditionally a preferred glue to use in many piano repair tasks. It can seem like a lot of work to use hot hide glue because of the equipment and preparation involved. This video goes through the steps to preparing hot hide glue so it can be used in your repair work.

If you want to see more of our Piano Tuning and Repair Seriesclick here to access the entire playlist.

Video Transcript:


Welcome to our next video here by Howard Piano Industries. Today we're going to be showing you how to prepare and to make hot hide glue for the purposes of using it for piano repair. Hide glue, the hot version of hide glue is used in a lot of repairs traditionally, such as repairing or reinstalling new hammers. You can glue action parts together that are broken or a lot of different places that you can use hot hide glue and piano repair. Traditionally it's a preferred glue such as replacing hammers because you can take the you know separate the glue you know at the point that it comes that you need to replace the hammers again. If you're doing repair where it's something that's going to have to be done again and sometime in the future, that makes it a good glue to use.

Hot Hide Glue Uses & Preparation

Oftentimes in the past, it's been used for such things as gluing on felt and leather and that type of thing. Now the glue for that is, we recommend PVC-E glue because it's a lot easier to use. Hot hide glue you have to prepare it, there's a little work as you'll see in the video to get it ready for use. It's mostly primarily used in the shop environment, if you got a workshop or whatever. Because you have to get the glue, let it set overnight before you heat it up while the glue crystals soak in the water. We're going to show you how to do that today and I'll show you the process.

Heating Preparation

One thing you need is something to heat the glue, I was able to find a number of years ago a crock pot or a hot pot here that heats the glue. You want to make sure you get it to the correct temperature, basically, generally they say you know around 130 to 140 degrees is a good temperature to be for hot hide glue. I've found a pot that will heat it, I set it on the low setting, it'll put it at that temperature. If you can't find one in that correct temperature range, it works if you can find something with a dial, something that has a variable adjustment on it that you can adjust a little bit at a time. Those are some options to think about when you're looking for a pot. They do sell glue pots, they tend to be expensive, I think this one I only paid about ten dollars or so. I found something that was a little less expensive or a more economical option that's been working for me for a number of years.

What I did in the beginning is I would put the glue, when I first started using it, I would put the glue inside the crockpot, but then I found I had so much extra glue at the end because you don't really end up using that terribly much glue for one job. It's not necessarily good to reheat it too many times. You can reheat it two or three times depending on what kind of thing you're working on. For hammers you always generally want to use fresh glue. If it's other things like felt or some of those other things that you know you can reheat it a couple times but every time you reheat it, it does lose some of its strength. It's not recommended to reheat it too many times. What we're gonna do here, what I did was to solve the problem of having too much glue at the end is I just took a cup, and put it down inside the crockpot. Then I've got water down inside the core the crockpot that will heat up, and then heat the cup inside the water. The water gets set down inside the water, inside the pot.

So it's small and you can even use a smaller container than this, and I use porcelain because you want to have something that's nonstick. I've seen somebody else that uses a small tin can that works too, that way you can just throw it away when you're done. Because this one's porcelain, I can clean it out really easily so and I don't use as much glue this way because it's a little smaller container.

Preparing Hot Hide Glue for Heating Process

What we're gonna do I've got my hide glue crystals here, and I'm just gonna put some of that inside the cup, and you know you're still going to end up with probably more than you need, but if you want to get the if you want to put you know at least probably you know fill the container at least a third full of crystals. That should be a good amount to get you started.

Of course, you want to make sure that the water level around the container that you're putting the glue into is at least as high as where the glue level is gonna be. I've got to make sure I have enough water in there and then once you're done, once you do that, we'll show you here we've got the glue crystals inside the cup, then what you're going to do is you're going to take water and basically, you know some people ask ''how much water should I put?'' What I learned and what I've always done is, I put enough water in and that you want to be careful on this, put enough water so that it just goes over the level of the glue and you want to do that right away.

Now one thing is as you let the water sit, you're gonna notice the glue, the water is gonna soak in. Initially, you put the water in and just get it to the level, so it's just barely above the level of the glue, and like I said, that's gonna soak in. You're gonna say "oh I must need more water" but it doesn't. Once you set that initial level, that should be the correct amount so I'm gonna pour the water in until it just goes over the level of the glue and then and I can see that it soaks in right away, in fact, I probably need to put just a little bit more in, there we go, just a little splash to make sure it gets in all the crystals.

Then what we're gonna do is we're gonna let that sit for several hours to maybe overnight. If you were to do it, if you want to work in the morning on something and you want your glue just do this part of the step the night before, and then by the morning, it'll be ready, let it sit, that that water needs to soak into the glue crystals.

Once it's soaked in then you can go back in a few hours or the next day and heat it up, and it'll be ready to use. That's the step we're gonna do now and in just a bit here we'll come back after the glues had some time to soak in, or the waters had time to soak into the glue crystals, and we'll heat it up and show you how that works.

Heating Process

Here we are we've come back we've let the glue sit for a while soaking up the water the glue crystals. We're at that point of being ready to turn it on, I can see that the glue crystals have soaked up the water and should be ready to turn on to get it heated.

It's been several hours since we put the water in, again we want to make sure the water level is at least as high as the level of the glue in our cup or the container there. I'm going to turn it on, I'm just gonna turn it on to low and the past I have turned it to high just for a little while to get the water heated up a little bit faster and get the process moving a little bit quicker but you do have to be careful that you don't let the temperature get too high too quickly so that it overheats the glue, because that can break it down quicker and it won't be as effective.

We've turned it on and now we'll come back maybe about an hour or so roughly and let it dissolve and melt is so that it heats up so that we can use it. We'll come back in just a moment one that's ready for us. We're back here with our glue all heated up and ready to use, I'm going to check it.

Sometimes, you do have to make adjustments, you know you set the water level when you first pour it in, but sometimes you have to add a little water if it's a little too thick. It's better to on the side of too thick because obviously, you can't make it thicker once it's too thin but if it's too thick, you can always add more water.

Checking Glue Viscosity

We're gonna check it and see see how we're doing with it. What I usually do is I've got a piece of wax paper here that I use to set my utensils on because it doesn't stick to it. If you stick it on a paper towel or something like that it's gonna stick but wax paper works pretty good. We're gonna check this here and see if we can get you a little closer here to take a look to see what our glue looks like. There we go, so as you can see that's the consistency that's close, probably a little too thick for what well-- that's probably pretty close and pretty close to what we want. If anything you can add a little bit of water you know once you start using it, try to see what it's like. 

Hot Hide Glue Demonstration

What I do is I've got, because we obviously want to keep it mostly covered but we still obviously have to access it. What I did, I made this board I just took a piece of this is a 1x1 by lumber or 3/4 inch lumber that I used and I cut a square out and what I did then was put a hole in it so that I can access my access the glue with the glue brush from from through the hole. Most of it is covered but there's enough room for me to stick that in there because otherwise, they have to keep the cover on and take the cover off and dip my brush in there every time I want to use the brush. Then that can be, not very convenient.

This is a nice thing here and the other thing I use if I have to stir it while it's going, I just use upright hammer shank here so we can do this and stir it as needed. I can use this, I can even set my stuff up on here if I need to or my brush, I can leave my brush. One thing nice about the hole is that once you dip your brush in it to get your glue and then use it for whatever. You can leave the brush here if you have to set it down and because it's over the hole or the steam is coming out, it's pretty much going to keep it so that the glue doesn't harden up on the brush for the most part.

For a lot of things with hide glue I like these little, and these are just little cheap kids paintbrushes that I got from the craft store, buy them like in a package of a hundred. So that's often what I'll use especially if I'm doing hammers or something, if I need to brush glue on something larger I use these glue brushes which these are ones we sell in our store. If you're like doing felt, putting glue on felt, this is a good brush to use. You can fit that down inside the hole and get a bunch of glue because if you're doing felt, you're gonna need to get more glue at once so that's a that's a good brush to use when you're doing that.

Basically, that's it, that's how you prepare the glue again you know and if you're working with it for a couple hours you know you want to check it, and stir it with again, I use a hammer shank or you can use anything that'll fit down inside the hole to stir it. If it gets a little thick which it will tend to do over time as you're using it, especially if you're working with it for an hour or two, you might have to add a little bit of water, but just keep an eye on the consistency to keep it and you get a feel for it as you start to work with it and use it more.

That's how you set it up, it's a little more, it's obviously more work than just using cold glue out of a bottle like PVC-E glue or there's even cold hide glue, but cold hide glue doesn't work as good as the hot hide glue. It's definitely a good strong glue for piano repair work and it's someone that can be taken apart down the road if need be. That's the advantages of using hot glue. It is a very traditional type of glue for piano repair works.