Keeping glue warm

[Harlan Barnhart]

I want to start using hot hide glue. I have a small cast iron double glue pot. My plan is to heat it on a stove top then carry to my workbench. How long will it stay warm enough? I thought of buying one of those desktop coffee mug warmers. Will that produce enough heat to keep the glue at usable temperature?

Peace,
Harlan B.

[Greg Wease]

I think you need continuous heat. I don't know about a coffee mug warmer but the "potpourri pot" I use ($5 at Goodwill) keeps the glue at 140 degrees.

[Bob Glenn]

I bought a small crock pot at Walmart for 4 bucks. I found the middle setting kept the water right a 145 degrees. I just set the glue jar in the water bath and put the lid on until I need to use the glue. You can also use a disposable plastic cup for the glue, then throw it away after you're done.

[george wilson]

Glenn,you are really bumping up the high end of glue warming. Too hot and the glue cooks,destroying the adhesive properties. I wonder if your temp is really lower than that as 140º is the recommended max..

[Sam Takeuchi]

I heard some people use bottle warmer. It might be a good way to go than buying one of those "proper" glue pots like "Hold Heet" (that's what I use, but bit pricey. I would have chosen cheaper option if I knew better when I got it).

[Harlan Barnhart]

Mr. Wilson, what is the upper temperature you would recommend?

[george wilson]

140º is what is called the top temperature. I use 130º myself. If you google hide glue temperature everyone says 140 is tops. I have a proper glue pot with adjustable temp. I put hot water in the glue pot,and a bottle inside it with the actual glue. That way,I keep the pot clean and new looking.

[David Wong]

I use a small Rival 2-qt crock pot (SCR200) with a removable ceramic pot. On low with the lid open, the temperature never goes above 110°. With the lid closed, the temperature never goes above 140°. So far, I have only used it to warm-up Old Brown liquid hide glue. I always keep an instant read thermometer in the pot to monitor the temperature.

[jamie shard]

+1 on the Rival pot

http://www.spurlocktools.com/id57.htm

[george wilson]

Spurlock recommends that glue be kept at 145 to 1500,which is just plain TOO HOT,repeat,TOO HOT. I wish people would not put spurious info like this out there. Please keep your glue NOT ABOVE 140º MAX. Google it and you'll see that everyone else says the same. If you actually cook the protein in the glue,it is not going to have decent strength,if any.

[Brett Robson]

http://woodtreks.com/animal-protein-hide-glues-how-to-make-select-history/1549/

Good video with some useful information on hot hide gluing

[Metod Alif]

The temperature ranges mentioned in that video are way higher than George Wilson recommends. I have no (yet) experience with hide glue, but George's advice is hard to surpass. He is consistently way up on the quality ladder.
Best wishes,
Metod

[george wilson]

Should have read 150º,not 1500!!

We used hide glue a lot being in a museum. If you subscribe to Fine Woodworking's website,there is a good glue talk by Ed Wright,one of my old journeyman,and now the last musical instrument maker left in Williamsburg. Sad.

[lowell holmes]

I know this is heresy, but I have hot glue flakes, not your liquid bottle stuff.

When I need hot glue, I cut the top out of a coke can and put it with the glue in it in a pot of boiling water. When it is liquid, I remove it from the heat with the pot of water and set it on the bench. I will brish the glue on and make the joints.

An old doulble boiler on a hot plate would work.

I've never had problems with glue joints failing. I've never used it in vennering or insttrument making, so my needs are much different than at the museum.

[Sam Takeuchi]

I use a small Rival 2-qt crock pot (SCR200) with a removable ceramic pot. On low with the lid open, the temperature never goes above 110°. With the lid closed, the temperature never goes above 140°. So far, I have only used it to warm-up Old Brown liquid hide glue. I always keep an instant read thermometer in the pot to monitor the temperature.

I've never used ready made liquid hide glue, but is there any benefit using that stuff warm? It seems to me the whole point of it being formulated to stay liquid is that you don't have to cook it or warm it to use it. What does that do?

[Trevor Walsh]

It thins it out a bit and can be really helpful if it's cold or you have a lot of area to cover.

[george wilson]

Liquid hide glue gets REALLY thin when heated. That helps it get into the grain of the wood better. There was an article some time ago in Fine Woodworking where glues were tested. The liquid hide glue was found to be stronger than the glue you make up. Now,there are several grades of hide glue. They did not specify which grade of glue they were comparing it to. For guitars I prefer the original type,as it dries harder and will transmit vibrations better. The reason liquid was found to be stronger is likely because it doesn't dry as hard or crystalline,and gives a tougher bond.

You can make cooked hide glue tougher if you wish by adding a little glycerine to it. Determine how much by experimenting.

You are supposed to first soak the glue in water,then add more water and heat it. Putting dry glue into BOILING water is subjecting it to 212º,which will cook the protein and weaken or destroy the holding power of the glue. It still might glue,but you may not be getting the most strength out of it. We also used hide glue in the cabinet maker's shop,which was connected to mine.

If any of you can access the Fine Woodworking site,I encourage you to see Ed Wright's glue talk and demo.

[Harlan Barnhart]

Brett, thanks for the Woodtreks link. Very interesting. I noticed he recommends 140 to 180 degrees! He also heats without totally dissolving the granules and he adds fresh glue right in with hot glue to adjust the viscosity. All things I have heard to be not recommended.

[Sam Takeuchi]

I see. That makes sense. Does it dry clear and achieve invisible glue line like hot hide glue? If that, I wouldn't mind using it for rosette and purflings for sure.

[george wilson]

Liquid hide glue leaves a light brown glue line. I have a supply of clear ,small pearls of hide glue that leave a much more invisible glue line. They use this particular glue in the furniture conservation shop in the museum,when invisible repairs might be needed.

Lyon and Healey harp makers used Knox unflavored gelatin for their hide glue. Their glue lines on unstained maple are really invisible. You might want to get some at the grocery store and try it out on some scraps of wood. The Lyon and Healey glue lines are really just not there! Their workmen used to eat some of the gelation with sugar for dessert at lunch.

The gelatin must be quite strong,because harps are under a great deal of tension. The smallish diameter necks at the top of the soundboards where the arch of the harp starts are glued up maple,and not that large. Incredibly faint glue lines.

[Casey Gooding]

When I did instrument repair, we used small glass jars (something like a baby food jar would be close) and used coffee mug warmers. It always worked well for us.

[Adam Cherubini]

I use a $20 electric burner from Walmart. Off the heat you have about 5 minutes before the glue cools and becomes non-ideal. 5 minutes is enough time for most jobs tho.

[Matthew N. Masail]

There was a guy over at the Delcamp Luthiers forum who did a test of different glues. he poured then into a container and let them dry for a several months, I recall he tested the samples again a year or so later. I don't recall all the results but the difference between liquid hide glue and hot hide glue was huge.
as Mr. Willson mentioned hot hide glue dries harder. the test showed that the hot hide glue had dried hard like glass, and made a ringing tone when dropped on the floor. the liquid hide glue on the other hand had dried to be like rubber, he could still dent it with his finger nail.
so this might not be important for furniture, maybe liquid is even better, but for musical instrument there is a clear difference. Just thought this was a nice piece of information to share.

[george wilson]

Glad you had that experience,Matthew. Another thing that might be wrong with glues that don't dry hard in musical instruments is that they might creep under pressure. Some glues,like old fashioned white glue,will let a guitar neck creep loose at the heel a bit,even though there is a tapered dovetail holding it in. I know this from personal experience from back in the 50's when I was learning my way along making guitars. That,plus the loss of some vibration transfer across glue joints. Though possibly small,it is best avoided.

[Kenneth Speed]

I managed to snag an old water bath glue pot so warming my hide glue isnt much of a problem. I keep my hide glue in the refrigerator when I'm not using it and pre-warm it by nuking it briefly in the microwave before it goes in the water bath glue pot.

Ken

[Matthew N. Masail]

Thanks George, but it wasn't me who did the test, I still have some way to go before I get to guitar making, which is where I'm heading. I'm planning on using HHG for all of the construction give or take headstock veneer and such maybe. I have an interesting question for you, if I may, I think your the only one I can ask who probably has the experience to give a real life answer .
I heard a story about Torres, saying that when gluing the back, he used to spread the glue and set the back in place, then he would wipe the back with alcohol or something and set in on fire for
a few seconds (the way I was told the fire went out by itself when done consuming the alcohol or whatever substance it was), thus reheating the glue for the best glue up. to do think this makes sense? would a few seconds or so be enough to heat the glue? and would it really not harm the wood?
I've seen experts say that the guitars top and back were glue on simultaneously.

[Trevor Walsh]

George, I love the Knox gelatin story. I've got some and while working on my little instrument I'll do something with the gelatin and have my lunch. Any reason making lemon flavored gelatin from Knox would be a bad plan? For the instrument, not the tongue that is.

[Adam Cherubini]

Spurlock recommends that glue be kept at 145 to 150,which is just plain TOO HOT,repeat,TOO HOT. I wish people would not put spurious info like this out there. Please keep your glue NOT ABOVE 140º MAX. Google it and you'll see that everyone else says the same. If you actually cook the protein in the glue,it is not going to have decent strength,if any.

While I agree with George, I hasten to add that sometimes this sort of discussion drives guys to pay crazy money for glue heaters and temperature monitors. This can cause some to race back to titebond2. Remember that we are woodworkers. We're not holding airplane wings on with this stuff. And we almost never need the mechanical properties these glues can deliver. So while it's good an technically proper to maintain this 10 degree temperature band, it isn't exactly required if your intention is to hold a dovetailed drawer together.

I've heated and used hide glue in wood fired hearths (i.e. no electricity). I look at it periodically, stir it, add some water if it looks like it's getting too hot or too thick. By all means, don't boil it. Otherwise, try it and dont' sweat it. Your project probably won't be ruined by using over heated glue. If you do overheat it, dump it out and make a fresh batch. There is a skill involved with using hide glue.

Only advice is that the cast iron pots (available in many antique shops with plastic flowers in them) really do a great job at holding heat and storing it. Oh, and if you are searching for one at your local antique emporium, get the sad iron next to the pot from the huge collection of sad irons and iron shoe lasts (someday I'll think of a use for them). The sad iron works great for heating veneers. I heat it on the same electric burner I heat my glue on. Though I've never tried it, I'm sure it would work fine on the hearth as well.

[george wilson]

Adam,as others have stated,a cheap heater and a thermometer will do. In the old days they didn't have our conveniences,but they used hide glue all the time and gained experience that many here don't ever get. So,a means to test is a good idea,I think. Having used primitive tools and means for many years myself,I have the experience,but I try to help those who are new at it. For instruments,where there are nearly no joints to hold things together,glue strength is very important,especially as the instrument is forever under string tension.

Trevor,I don't know what the addition of citric acid would do,so I must advise use of the plain Knox.

Matthew,I can't recall if I've heard the burning alcohol story. Personally,I have never glued on the top and back at the same time. I see no practical reason to do this. It seems like a difficult way to go,and your guitar sides could get out of shape or squareness. If it was done,it was done by those who had the experience and expertise to do it that way.

[Sam Takeuchi]

I've heard of the Torres alcohol burning assembly method. It was in Jose Romanillos' Torres research book: Antonio de Torres: Guitar Maker - His Life & Work. You can read that bit online here (http://books.google.com/books?id=EOMU8U7qNcsC&pg=PA134&lpg=PA134). It's a very nice book by the way. Torres aficionado luthiers would definitely find it interesting, but it's bone dry as far as reading material goes. About 75 pages of Torres biography and 220 pages of technical details of surviving Torres guitars.

[george wilson]

Oh,I have that book and read it a while back. Getting too old!! I think I'll feel safer not doing that,though. Soon as I did that,I'd probably crack something from the heat,or discolor something. Maybe cook the protein in the glue.

It is a good book though. I think I'll read it again.

[Jack Curtis]

Isn't that how you patch inner tubes?

[Sam Takeuchi]

Isn't that how you patch inner tubes?

Inner tubes?

Edit: Oh, for tires?

[Jack Curtis]

Yeah, for tires, 100 years ago except for bicycles. I was thinking of this because I've got one to patch in the morning; but I'll probably just use unheated glue.