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I try really hard to use hot hide glue wherever I can on the guitars I build. I am thinking about experimenting with double sides on my next build (when I finish up the two on my bench right now). Other than the issue of pre-gel open time with the hot hide glue (something I am pretty familiar with and think I can manage), are there any other issues with using hot hide glue as the adhesive for gluing the sides together? I know that most of you who use double sides are using something else, like epoxy, and I wonder if it is due to more factors than just the open time issue.

Thanks for your help.

FWIW I/m doing the same 2 x sides but using T3 titebond. My 2 cents HHG unless you use a gel suppressant takes too long to laminate for me too much moisture curls the sides before clamping here in KC , PS I like to take my time .I use 2 plastic covered cauls. I/ve not used HHG for laminating,
but experiment on scrap to see if it works for you.

Ernie--

If moisture (and resulting curling) is a concern, then I think hot hide glue and any Titebond version are going to have similar problems, because there is water in all of them, right? Letting the parts stay in the clamps overnight to fully dry out will hopefully minimize any ripples.

As I said, I think I can manage the open time with the hot hide glue. I already glue tops and backs to sides with HHG. I plan to use the normal tricks: Heat the parts, perform dry runs so the actual clamping goes fast, use more glue than is really needed so it maintains its heat better, etc.

Any concerns other than open time? Again, thanks for the help.

I used a dry powder (UF glue) urea formaldehyde ?? called unibond for veneering 2 walnut veneers to a .075 piece of walnut for the gtr sides.I think it was a glue that dries very hard and brown has about 1/2hr open time depending on ratio of water. I also used it to laminate curved 1/8in C pieces for chairs the long open time helped with alignment I had, 8 ,1/8 in veneers, I/ve tried T1 for laminating but did not like it in my hot an humid garage 89 today and and abt 60 % humidity. The glue started to dry before I scrambled to line up the clamping cauls. I used T3 this morning on an oak /walnut veneered sides for a small CL gtr. If you can use the HHG go for it , hammer veneering is one technique for gluing veneers to a solid piece using HHG . Google it on youtube . I made a simple veneer hammer from a piece of aluminum. Back in the day cabinetmakers used HHG or fish for laminating hope this helps.

Don I would not use HHG for laminating sides.

The beauty of HHG is that the resulting joints are serviceable and can then be taken apart. There will never be any need to delaminate double sides for the most part.....

I get-it that lots of us like to use traditional and superior materials etc. and HHG is most certainly one of these but it's not superior in all applications or at least measurably superior in all applications.

There are two criteria for when I want to use HHG if possible and practical.

1) Sonic impact, does the application intentionally carry or reproduce vibration?

2) Is the application needing to be serviceable in time, something that may reasonably be assumed to be necessary perhaps... to take it apart some day.

It most certainly could be done with continual heating, perhaps what the violin guys use "hot rooms" and boxer shorts but what's the benefit?

Instead I would use something that the guys here have had good luck with for laminating sides.

What Hesh said --- Also Franklin makes "non-bleeding" slower set formulas for laminations. Seems to me the very nature of HHG would have you playing beat the clock -- personally I hate that.

The few I know that make laminated sides use Epoxy and a vacuum press set-up -- but bleed through is mentioned as a concern.

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Ken Cierp

http://www.kennethmichaelguitars.com/

Titebond 3 would be my last choice for laminations. The stuff is like rubber. Big time creep. Which is why it is great for exterior doors where you have large cross grain joint surfaces and you want your glue to give a little. In a guitar side I would want something that dried hard and brittle. TB3 is their softest setting glue. Titebond 1 extend their least creepy.

Bleed through not a concern if using epoxy and going to use it for a pore fill. Bleed through not a concern with Uni-bond if you use news board (thin card board) and or craft paper. Any glue that comes through is absorbed by the paper and stays localized. Easy to remove. Rubber or similar non absorptive type things make a mess if any glue come through. The glue hits it and spreads along the surface of your work piece. PITA.e

My order of preference would be a Urea-formaldehyde (Uni-bond), Epoxy, Titebond 1 extend, Polyurethane. With the Uni-Bond being far and away the first choice with the other glues being used where their particular properties make sense.
I also don't like the idea of a double lam. 3 is more better. Balanced construction, and puts the glue lines away from neutral axis and closer to the outside where they can stiffen the assembly. Way less spring back. Mahogany works fine for the inner lam.

L.

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Cut to size.....Beat to fit.....Paint to match.

Hesh and Ken--

I completely understand and consider valid the "why go to the trouble of doing it that way when other things will work" perspective that you are expressing. I just have a different perspective.

So, if you could, I'm asking you (and others with comments to share) to indulge me momentarily and assume that, for whatever reason, I want to do it that way. Aside from the pre-gel open time issue, is there a reason why hot hide glue would not be a good adhesive to use for gluing double sides together?

After all, reversibility is not the sole virtue of hot hide glue, and I don't limit my use of it to those instances where I might want to take the joint apart someday.

Link--

I understand the pecking order of adhesives you have outlined. Any perspectives on hot hide glue? It is not on your list, yet it is hard and brittle and does not creep. Other than the need to hustle to get the joint put together, any downside to hot hide glue that you can see?

Hey Don, if you want the brittleness of hide glue with lots of open time, you might want to try fish glue.

Steve

What do guys think about this approach to laminated sides?

https://www.youtube.com/watch?v=4feW2TbWbcw

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John Lewis
Wannabe builder owned by 2 crazy dachshunds

John, I'm looking forward to watching that.

Just want to piggyback on Link's suggestion to use unibond. I used it and had zero bleed through, zero issues. I mixed
For quick set, had it
under vacuum for an hour in a 100 degree shop, took it out of the bacuum bag and put a bag of pie weights on the waist just to keep it snug. The sides were also dead flat when I leveled them for binding (solid bending form).

Don, I understand that you want to use HHG, but thought I'd relate my experience.


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Don, I just had an idea. Do you bend using a blanket? You could laminate as soon as the second layer comes off, using the residual heat to keep the glue from setting.


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I use HHG to laminate sides. I had to build a series of continuous cauls that go from tail block to neck block. The cauls are 1/4" thick and 1 1/8" wide to accommodate the width of a spring clamp. I needed the cauls to match the curvature of the form to prevent ripples from occurring in the veneer. To do this, I applied urethane sealant that I use in the roofing business to the inside of the caul. The sealant is about 1/4" thick. I then press the caul into the form and let the sealant cure. The caul is now the exact curvature with a little bit of a cushion. I apply hide glue to an area about the size of two cauls before clamping. I then move through the sequence until the entire side is clamped. I numbered the cauls so I will know the exact spot they belong.

I have done two guitars this way and the results were very good. The side was very stiff.

James--

I'll go you one better regarding the blanket. If I perform dry runs and simply can't get clamped up in time to beat the gelling of the glue, maybe I can try something completely different:

Spread the glue on a cold pre-bent side, let it gel on purpose, applying a few layers of it to get it on there good and thick, then put the pre-bent sides together (gelled glue between them). Stick the blanket under the bottom side on the form, then clamp loosely. Turn on the blanket to melt the glue, and tighten the clamps as the glue melts, then turn off the blanket. Let it cool, let it dry overnight in the clamps. The trick would be getting the heat setting right, but that's always the trick.

I would rather get it all clamped up while the glue is hot, but if that won't work, this might.

Steve--

Great to hear from someone who has done it!

HHG certainly isn't my choice for laminating sides (that would be unibond)...but I don't see any reason you couldn't do it if you wanted to.
I would think the easiest way to go about it would be to brush one of the mating surfaces fairly liberally with HHG, let it gel then position and clamp everything in place and heat it up again to reactivate the glue and go back and re-tighten all the clamps.

Don, To answer your question, there is no reason that hide glue wouldn't work in that it is strong enough, creep resistant enough, dries nice and hard. However, the short comings I see are: not gap filling (in a lamination of this type your rarely get perfect mating and with a 2 ply it would be exacerbated because your laminations will be thicker. ) Short open time and if it gels you will have a weak bond.
If you had a helper and set everything up well,(hot room, heated mold and parts, minimum clamps or a quick vacuum), you could pull it off. I wouldn't trust it as much as Uni-bond or some of the others but not because of the glue but because it is not best for this type of operation. Swimming upstream. If you are really committed to using it I would do a bit of practice. Success or failure you will learn a lot and the pursuit has value. It can be done and I think you could do it. I would use Uni but you already know that
L>

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Cut to size.....Beat to fit.....Paint to match.

In light of some studies referenced in threads on this forum cold hide glue seems very close to hot in bond strength and I bet it would work just as well for laminating sides.

That said I am a Unibond fan for the reasons mentioned above.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Maybe I could add some urea to the hot hide glue to extend the open time. Maybe not enough urea to turn it into the equivalent of Old Brown Glue, but enough to give me some more leeway.

I have thought about it Don and wondered if it would work.

A side bender as a clamping form with a heating blanket turned down to hold 140 degrees should give a lot of open time.
The other problem is the sides need to be held until most of the excess moisture is gone to avoid strangeness. As long as the glued sides are trapped between impermeable forms/cauls the water can't escape very well.
I think that's what is behind these forms at Collings. let the moisture equalize to ambient air while holding them in position.
Good on you for being stubborn and wanting to do it!

I agree with Link but if you did want to use hide glue and you didn't get it together before it gelled couldn't you mist the sides and put then in your side bender and reheat the glue? Just a thought.

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Ken Franklin
clumsy yet persistent
https://www.kenfranklinukulele.com

David--

Thanks for the positive feedback regarding my mule-like tendencies! I'm not always like this (maybe self-perception has a lot of blind spots), but this feels like one of those things where questioning assumptions might not be a bad thing, and maybe some good will come of it.

A few thoughts about the concerns raised so far (other than open time):

Gap filling. True, hide glue is not the best at filling gaps. But I'm not so sure I would need or want to have big amounts of "stuff" filling a small void between sides. As long as the glue joint is good in most places, I don't see a problem with a little air here and there. The goal will be to get the sides thin enough, and the clamping pressure strong enough, to minimize gaps, but I feel like the few that are inevitable can just be there and not cause problems.

Water escaping. I don't know if those of you who have used a lot of hot hide glue have noticed this, but I feel like my hot hide glue joints shed the moisture way faster than if I had glued them with Titebond. I have had the experience with Titebond that David referenced, where a joint won't fully dry until you expose it to more air by releasing the clamps. But those same joints made with hot hide glue seem to dry out way faster. Maybe that's not the common experience, but it is something I have noticed. I guess my point is that I'm not too worried about the joint not drying out well enough. With hot hide glue, the moisture seems to escape somehow, no matter how I clamp the joint.

Thanks to all for tolerating my focus on the specific question asked. I trust and know that everybody who offers suggestions regarding other adhesives does so with the intent to help, and I appreciate that. But I just have a different focus. I think I have a good idea why many folks think Unibond is the best thing to use; but why specifically would hot hide glue be bad, other than the open time issue? What I am hearing is that open time is really the main downside to using hot hide glue for laminating two sides. If there are others, I will benefit from knowing about them before I experiment.

Again, many thanks!

FWIW I just bent the oak/walnut 3in sides.100 using T3 it took abt 18 min and I went vy slowly. and used low heat on my omega heating blanket 150-200 deg F.I used the t3 after reading a report in fine woodworking on testing strength of their glues an t3 is one of their strongest glues. iF and when you use the HHG I would like to know how it worked for you thanks

I think the main reason HHG would be "bad" for laminating side is because there are easier and quicker ways to do it. The reason for laminating sides is to create a super stiff rim set, so the top (and back if you build responsive backs) are not robbed of energy. HHG isn't going to be any better at bonding versus epoxy or unibond. and it's not going to magically create a stiffer rim set either. But it is going to take a more concerted effort to do the same job.

Don, I respect your idea however there's no benefit to using HHG vs any of the easier methods. As long you get the same result though, fill your boots.

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Maybe there is a related, but slightly different, question I should ask.

There are folks who don't laminate sides, but have experience with the characteristics of different adhesives, including hot hide glue, so they have a viewpoint based on that. There are folks who have actually laminated sides, and probably also have experience with various adhesives, including hot hide glue, but they have not tried to use hot hide glue for laminating sides. They have their viewpoint based on their experiences. Both of these are valid perspectives, and I appreciate the folks with those perspectives sharing their thoughts.

The list of folks who have actually tried using hot hide glue to laminate sides seems short. If you have actually tried to use hot hide glue to laminate sides, I would love to learn more about how that went, regardless of whether it went well or poorly.

Again, thanks to all for the input.

Don, I think you have answered your own question. Those of us who actually work with laminations have not chosen to use HHG. Using HHG for laminations doesn't sound practical.
However, if you want to experiment with it, please do. Do three sets of sides: HHG, Unibond, and epoxy. Share with us what you learn. You may even get some builders who will follow your lead.


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