Liquid Hide Glue vs Hot Hide Glue

[Mdinterman]

I just got my Popular Woodworking magazine and Christopher Schwartz wrote an extensive article on liquid hide glue which is different than hot hide glue. According to the article, liquid hide glue is the same as hot hide glue with the exception that liquid hide glue has urea added to it which depresses the pour point and allows it to stay liquid at room temperature. Liquid hide glue, according to the article has longer "open" time than PVA glue and obviously hot hide glue.

Hot hide glue dries/cures to be very hard thus many believe it produces better sound in an acoustic guitar. My question to experienced luthiers and builders is "does liquid hide glue share the same acoustical benefits as hot hide glue?"

On an amusing note, the article says there is unconfirmed lore that liquid hide glue was discovered by French woodworking apprentices who were trying to sabotage their masters' work by urinating (urine has urea) in the hot hide glue.

[John Arnold]

It is my understanding that liquid hide glue will dry just as hard as hot hide glue.....provided it is not too old. If it is too old, it will never harden properly. The problem is in knowing when that is the case. Franklin liquid hide glue has a date code on it.....just like their Titebond. There is an online description of how to read their date codes.
I have never used liquid hide glue, but I throw Titebond out when it gets a year old. I would be inclined to test any liquid hide glue that is more than two months old. Spread it thin on a piece of paper and let it dry. Flex the paper to test for hardness (or just try gouging it with a fingernail).

[Alan Carruth]

My experience with liquid hide glue is that it's very hard to tell when it has gotten too old until you've used it, and then it's too late. I don't know any luthier who trusts the stuff for any critical application.

[redir]

I built a guitar with FLHG about 25 years ago that has been through hell and is still going strong. It was a fluke one of a lucky stars kind of thing. You should just plain and simply not use it for building guitars.

Having said that, I get tired listening to arguments about the type of glue as far as tone goes. IMHO anyone that claims that one glue is better than the other as far as tone goes lacks a basic understanding of the chemistry and physics that is how glue cures.

Hint: It's not a 'gasket' that holds the wood pieces together.

There are a whole host of other reasons however to choose one glue over the other.

Popcorn

[Slight Return]

If you want a good read on this, look into "Hide Glue: Historical and Practical Applications" by Stephen A. Shepherd.

For a while I was mixing a small amount of salt into fresh hot hide glue to extend the open time. I even ordered a tin glue spoon for hot hide glue from a tinsmith. Have a boutique hammered brass glue pot and a hog hair brush and warmer plate and all that fancy stuff.

I used hot hide glue to repair a vintage all cherry red Gibson B-25 last year. Bridge reglue. Most of the time I've used it on bridge reglues on more expensive guitars, and it's still my go-to glue in those cases, as much of a pain as it is to work with.

The guitar was so valuable that I didn't want to take any chances, god forbid it needed any more work in the bridge area in the future. And I'm skeptical of the strength of Franklin liquid hide glue.

(I've heard Old Brown Glue is a very good and very strong liquid hide glue, which might be worth looking into)

Anyway, about the B-25: I wanted a reversible but strong glue joint. I will say the crackling effect looked very, very good and blended perfectly into the checked and cracked nitro finish. And it held the bridge down very well.

Anyway, I reglued the bridge on my Blueridge 12 string and used hot hide glue for it. That has not lifted even a tiny bit. It's holding up very well.

As for the tone? I can't say I notice much difference at all. If any difference at all. Maybe knowing that I used hot hide glue is a nice novelty for me, but as for any perceivable difference, I don't think there is any.

Of course, I could be wrong.

But I'm even more skeptical as far as tonal differences between liquid and hot hide glue goes. Although Stephen Shepherd (if memory serves) seems to believe that hot hide glue is the gold standard for all woodworking glues. And so do a lot of other people.

I'm not sure what to make of that assessment myself.

I would say hot hide glue has some valuable uses, but I'd reserve them exclusively for jobs where reversability is desirable. Or where the crackling effect would boost the aesthetics of the repair, such as on a bridge reglue on a vintage, nitro finished guitar with a lot of checking and cracking. That B-25 came out looking great and while it would've been fine with another glue, it was a plus.

I actually have a heat lamp near me most of the time when I'm using hot hide glue just so I can extend the open time by keeping the area I'm working on around 100 or 110 degrees. It isn't very user friendly in my experience.

I've used liquid hide glue for refretting and like it a lot. Cleanup is easy and having some glue in the frets helps lock them in there. I've also used superglue (and have also had to remove frets I've superglued in, in my own guitars, and have had 0 issues with that), and superglue is certainly even faster (whip tips) and maybe even superior for filling voids due to its capillary action.

I've heard of people using hot hide glue for refretting but I don't know if there's any real advantage to that. Not to mention the pain of prepping the glue with heat and having to use a fresh supply vs. just using it straight out of a bottle (or one of those Fine Line applicators I'm a fan of...although the glue is so thick it can be a little cumbersome, which is why I use a pair of pliers to squeeze the bottle to get the glue to come out of the needle).

I do think it has a lot of posterity, and it does have a look that you just can't replicate with other glues. As for differences specifically between hot hide glue and liquid hide glue...I'm not sure there is much, if any, at least as far as tone goes.

I would imagine the hardest part would be gluing the top and back onto the kerfing, as it's such a large area to pour glue around, and you don't have much time to work with hot hide glue.

I've never used the glue spoon for that job but I imagine that would be the way to go.

Some people are convinced hide glue sounds better. I'd be hard pressed to believe that, but then again, I have felt how hard hide glue sets up, and it gets a crystalline structure, so....maybe there is a degree of truth to that.

Then again redir could very well be right and different glues might have no tonal differences whatsoever. It seems like a moot point to me and effort would be much better spent on every other aspect of building to affect tone.

The only reason I could ever see myself using hot hide glue in guitar building is to say I did it. It IS cool, and it does have posterity and "vintage" esque value, but as far as the real, practical application? I really am not sure and think it any differences are probably blown way out of proportion. Just my opinion.

I'm an odd duck and personally I absolutely love the smell of fresh hot hide glue. Kind of like incense to me, but better.

The only deal breaker for me is how much harder hot hide glue is to work with than other glues.

However....you can store the dry granules indefinitely. So in that sense it lasts "longer" than other glues, as you make up your batches fresh each time. No throwing excessive amounts away or having it go bad. You just make up what you need as you go.

All right.

I need a drink now. I just hope I don't down a shot of hide glue instead of scotch by accident. Probably high in protein though, and I've heard gelatin is good for you....

[tahoeguitar]

I used liquid hide glue to glue the bridges on my first two guitars. They came off after a couple years... so I don't use it anymore for anything. I use HHG for gluing on the neck and the bridge on all my builds, and for most neck re-sets and bridge replacements..

Hot hide glue is pretty easy to use for if you heat up the parts to be joined beforehand and get your glue mixed to the proper consistency. Gluing on a back or top to the kerfing is kind of challenging because you have to work real fast with no mistakes, and have the whole thing aligned and clamped in less than ten minutes (IMO).

I use HHG for all vintage repairs. I use LMII glue to build with unless asked for HHG.

[murrmac123]

Originally Posted by tahoeguitar

Gluing on a back or top to the kerfing is kind of challenging because you have to work real fast with no mistakes, and have the whole thing aligned and clamped in less than ten minutes .