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Like many folks here, I mix my hide glue in a small squeeze bottle, just enough for a job or two. I've recently gotten into a new batch of glue, and I'm noticing that the glue has turned liquid in the bottle at room temp while I'm waiting for the glue pot to heat up. Shop temp today was ~75 degrees and in less than an hour the glue went from gel form out of the fridge to full runny liquid. I've been using hide glue a long time and never seen this occur until I started using this new batch of glue. In my experience it has remained in a gel state until heated in the water. Has anybody else seen this?

I haven't had any glue failures with this new batch but it makes me wonder. The first time I use it after mixing a new portion it has behaved normally, but once it goes into the fridge and comes back out for the next job it liquefies on its own and seems runnier than the original consistency. I'm careful about the temperature and don't let it get too hot, which I thought might be the problem at first. I haven't used any of the runny glue, and I dug through the shop trash and tested my offcuts from bracing the tops and backs. Wood failed before the glue on all the pieces I broke, so I don't think I'm in for any surprises down the road. My gut instinct is to toss the bag and go get a fresh one, but I hate to waste a 3/4lb bag of glue if I don't have to. Any advice is appreciated. Thanks!

You tested it and it works. That seems good enough to me.

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Hutch

Get the heck off the couch and go build a guitar!!!!

Gelled hide glue should not spontaneously re-liquefy at room temperature. Something is up. I’d strongly advise against using the glue for any stressed joint. Possibly you could use it anywhere you’d use a commercial liquid hide glue (binding etc) but I’d be nervous to even do that as at least with products like “Old Brown Glue” we know its behaviour is due to the added urea. With your glue, the behaviour is a little mysterious.

Did you buy the glue recently? Have past bottles you’ve mixed from these same granules behaved ‘normally’? (eg not un-gelled themselves unexpectedly) Who was the supplier? Have you tried mixing up a fresh bottle from the same granules to see if it also displays this behaviour?

I don’t like to waste raw material either but life is also too short to spend time needlessly reworking things (or apologising to customers as to why their bridge fell off), so I would be ordering up a new bag of glue if this happened to me.

Zac--

There is this episode of Giligan's Island where they discover this tree with sap that works wonders as a glue. But unknown to them at the beginning, it loses its hold after a few days. They repair the SS Minnow with it, then a few days later the darn thing sinks in the lagoon. Again.

I'm cautious about the hide glue that goes on my guitars. I just don't want any failures. If a batch of my hide glue starts acting weird, I get rid of it. Your batch of glue is acting weird. So, if I were in your situation, I would get rid of it, or at least not use it on things I care about, like guitars.

I would weigh the cost of a new bag of glue against potential future repairs, plus the weight of uncertainty…

+1 on the Gilligan's Island episode. Something seems wrong unless you added some urea or salt to make a liquid hide glue and perhaps forgot about it.

Something isn't right. Even in 100 degree Texas, my HHG doesn't do that. The guy I get my glue from would replace it without a question.

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https://www.facebook.com/profile.php?id=100008907949110

Where did the glue come from? Return it for a refund or replacement. Please let us know where it came from it sounds defective.

You can test it for how it handles now for sure but you can't test it for what it's going to do in 25 years......

Also I thought Mary Ann was cuter but that's just me.

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Ann Arbor Guitars

That is exactly why I refused to let Gilligan work on my guitars

+1 for Mary Ann!

Yeah and Gilligan was a pot head, like me

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Ann Arbor Guitars

There are microbes and fungi that attack hide glue - one reason hide glue goes rancid in a few days if left in the open. If you are keeping the glue in the frig rather than the freezer the higher temperature (40F+/-) may be warm enough to allow them to grow and weaken the glue and when moved into room temperature conditions, liquify. The culprits could be living in the refrigerator or could be on the surface of the glue granules. You could try adding some fungicide to your next batch and see how it behaves. If you are storing "leftover" glue in the frig you might try the freezer instead it to see if that makes a difference.
I had some instruments whose hide glued joints lasted well over 100 years that completely came apart after being stored in a humid environment where mold developed. Microbes and mold love organic glues.

+2 on Mary Ann

Thanks for the replies everyone.

I agree that something's up with the glue and I hopped in the car and drove 100 miles round trip to the nearest Woodcraft to pick up a fresh bag yesterday.

The batch of glue in question was quite old and I'm not exactly sure where it came from. I got it in a group buy from a luthier group I'm part of years ago, just a pound of glue in a Ziploc sandwich bag. I hadn't considered it, but I guess there's a possibility it was mixed with urea before I purchased it. No real way of knowing. Don, I know you add salt/urea to your glue, in your experience have you noticed that it might degrade the glue after multiple heating and cooling cycles? I've never added anything to my glue, I just mix it a little thicker or thinner depending on the job at hand, so I have no frame of reference.

To be clear, the glue behaved normally when first mixed. It's only after a couple of heating and cooling cycles that it started acting strangely, and I never used any of the glue that liquified at room temp. I tested the offcuts from bracing and the wood failed before the glue on every piece, and I gave an unbraced top I've joined and thicknessed a good hard flex yesterday and the joint held fine. I also tend to stress test as I build, flexing and tugging glue joints just to make sure something doesn't fly off after I've glued it up. I haven't seen or felt anything to worry me so far. I'm not selling guitars, so this one should be around for a good while for me to keep an eye on. All the same, this batch of glue is going in the trash.

Zac—

First, just to clarify, I use urea as an additive, but not salt. Nothing against salt; I’m merely used to the way urea works, so I stick with it (pun intended).

Second, if I had to speculate in this moment, I would suspect the multiple heatings and coolings as being the thing that messed up your glue, not the combination of an additive and the multiple heatings and coolings. Hot hide glue is protein, and I can see the protein being adversely affected by heating up and cooling off lots of times. I also draw on my one bad experience with hot hide glue, which came during my “cook a lot of glue and bottle it” phase. I would bottle it in small plastic bottles and freeze them. As I needed glue, I would move a bottle into a “use then refrigerate” cycle. That bottle would get used multiple times, heating then cooling then heating then cooling, etc. at some point, I started having adhesion problems. None of this involved urea (or salt). I wound up revamping my process, and I have had zero adhesion problems since I changed.

Current system: No cooking glue ahead of time. I mix and cook what I think I will need for a specific operation. I only save the leftovers (unrefrigerated) if I will be gluing more over the next two days. But I don’t have a lot of leftovers. I have gotten good at predicting how much glue I will need. If I run out, I cook a bit more. If I have small amounts left over, they just get washed down the drain when I clean the glue pot. More details of how I work with hot hide glue are in one of the OLF Roundtable recordings (can’t remember which one). Happy to discuss offline, too. Just let me know if that would help.

EDIT: It was episode 4 of the Roundtable. Here is a link to the recording: https://youtu.be/pFxZjjU5MCc

This glue issue has been bugging the hell out of me, and I've been puzzling over it and thinking about all your responses. Clay brought up the issue of microbes and mold, and yesterday as I was heating up the glue pot it finally hit me - contamination is the most likely culprit in this case.

In the past, I mostly just applied the glue with the squeeze bottle. I've been trying to work cleaner, and recently have taken to opening the top of the bottle and dipping a small brush into the glue to paint both surfaces before clamping. In between applications, I just put the brush back into the water of the glue pot to keep it from gumming up. When I'm done gluing, I squeeze the water out of the brush and set it in a coffee cup to dry until I need to use it again.

I usually put fresh water from an electric kettle in the glue pot (Rival Hot Pot) every time I use it, but I haven't been draining the old water until then. It never occurred to me that I might be contaminating my new glue with leftovers from the last batch I took the glue pot and brushes to the house and gave them a thorough cleaning last night, and I'll be revising my whole process going forward to minimize the chances of contamination.

Thank you to everyone who responded to this post - I'm not a very active poster but I've been around for over a decade and benefitted greatly from the combined knowledge of the forum. It's nice to know there's help here when needed!