Primer on getting started with hot hide glue.

[Brian Evans]

The current thread on titebond has me rethinking its use in my guitars. I vacillate between wanting to use the most modern techniques and materials, and the most traditional. For example, I am thinking of vacuum bagging carbon fiber in epoxy as a side laminate and I am thinking of changing to HHG for all normal glue-ups. Seems daft even to me, but there you go.

Is there a primer anywhere on our site, or elsewhere, that would teach me the techniques, equipment and materials for using HHG?

Thanks, Brian

[Barry Daniels]

Have you tried the library or just searching the current discussions in the MIMF? There is tons of info there.

[Brian Evans]

I did, I found discussions on using it, but not the ABC's. Very basic things like mixing it correctly, cheap and cheerful heating pots, storing between uses, etc. Mind you just because I didn't find it doesn't mean it isn't there. I thought someone might have a thing they remembered from when they learned how to use it for the first time.

[Barry Daniels]

I found 399 discussions on hide glue in the old library. It's all there. But we can have a new discussion about it if you like.

Be careful where you buy your HHG. Some sources cell import stuff of questionable quality. Mine came from the Milligan and Higgins Company which is the last glue factory in the USA. To mix it, put granules into a glass jar and cover with cool water. Let it sit overnight. Next day put it in a pan and heat slowly to 145 degrees F. Let it cook for a few minutes and then I pour it into small plastic squeeze bottles that get stored in the freezer. They keep there for years. When needed, take one out, put it in my mini crock pot and heat to 145 degrees F. Once you get your method in place it is actually super easy and kind of fun. Makes you feel old school. I like the smell of it too. Sort of a beef stock thing.

Glue application needs to be quick and it is helpful to warm up the wood beforehand. You want to have the glue on and the joint closed and clamped in less than a minute or the glue might enter a gel state which will cause joint failure. This is especially critical on top and back plate joints because being so thin, they cool out quicker. A heat gun is your friend. Do a dry run on the operation to work out the movements and have the necessary tools at hand.

Cleanup is easy with a damp rag or you can wait till the squeeze out gels and pull it off then.

Keep in mind that hot hide glue is really thin and your joint needs to be perfect. There is no gap filling property in hide glue.

[Mark Fogleman]

As far as directions just follow the directions on the can for initially mixing it up with water. Your objective is to end up with it heated to ~140f and the consistency of non fat milk. As far as a good cheap glue pot I would suggest using a "Hot Pot" type of adjustable kettle/cooker as a double boiler and a good thermometer to find the setting needed to hold your hot water at 145F. I also use a small plastic squeeze bottle floating in the hot water bath for applying and storing it and only make a few ounces at a time. A small glass jar works well also.

The thing to do is to play with it and see how it works and how it looks/feels when you allow it to cool to a point that it gels on pieces of the types of wood you plan to use it on. Gelled HHG will stick two pieces of wood together but the joint will not be as strong as if it had been put together with hot glue.

[Todd Stock]

A Saltan plate warmer (check Ebay) and a heat gun can ease your transition - warming braces, bridge plates, fretboards, and bridges makes thing a lot easier. Over time, as you get both more comfortable and more efficient in your use of the adhesive, fewer and fewer glue-ups will need warming or supplemental heat...about the only thing we still use the plate warmer for is bridges (we use 315g, so higher gel temp( and the gun is used for linings and post-box closing.

We run a Proctor Silex hot pot (six years and counting...previous Rival pots ran 18 months or so) with cutout for an 8 ounce jelly jar (bridge, fretboard, bridge plate, linings, other large surfaces) and a 2 ounce squeeze bottle (braces, binding, small parts and repairs). The pot also provides 150 degree water for cleanup and a place to rinse brushes.

On making up glue, fill an 8 ounce mason jelly jar (the wide mouth helps) with 2-3 ounces dry granules by volume and cover with distilled or purified water...add water to top as required. Once there's no more water being sucked up by the glue, toss in the pot and heat. Once liquified, I skim any contaminates and stir well, then use. The jelly jar or squeeze bottle of glue will keep in the fridge for at least a month if using high clarity 192g and weeks for other grades, but each reheat will reduce strength...our shop rule is discard if the glue does not 'string' nicely with a fingertip test. Keep the glue tightly capped in the fridge, and immediately discard and sterilize the container (if retained in use) before refilling. We store dry hide glue in gallon and 5 gallon paint cans/sealed buckets...cool, dry place...keep the gel silica pack in the glue to suck up excess moisture...if on adding water your glue does not absorb water, it's been improperly stored.

Use is easy...squeeze-out is mandatory...slop it on, position, get the glue line thinned with initial pressure, and get the clamps, go-bars, or tape on only after closing the joint. If a cold joint is suspected (distracted or otherwise delayed in closing joint), heat with gun until the gelled squeeze-out liquifies...keep heating for another 5-10 seconds, close the joint, and clamp. For joints line linings, we don't worry too much about gelling - get them positioned, close the joint and clamp (with something that can take the heat, like clothes-pins or binder clamps), then hit with the gun until beads of squeeze-out appear.

On clean-up...let hide glue gel, no matter how much squeeze-out is there...it can be tempting, but let things get to almost 'Gummy Worm' consistency, then - using a wetted popsicle stick sharpened to a 25 degree skew and a double bevel, use the knife edge to slice the squeeze-out free of the assembly, collect, then use hot, wet paper towels to mop up the rest of the adhesive. Work the joint with a damp paper towel and look for any remaining residue. If the assemble is allowed to dry under clamp pressure, the excess water (which you are wiping off anyway as the final step of cleanup) will not be an issue. Sounds like it takes time, but so much faster than Titebond or fish to do.

192g high clarity for almost everything except bridges; 315g for that job, because you can unclamp in 6-8 hours and never have to worry about the joint. 192g wants more drying time for highly stressed joints. Old Mill Cabinet Shop has the best prices I've found on 192g and 315g glue, other than ordering a 50 lb bag directly from M&H.

[Alan Carruth]

The 'correct' temperature for using HHG is to some degree a matter of opinion. Everybody says to use it at 140 F or so. That certainly works, but in my mind it's the maximum temperature, since that's when the proteins that make it up start to break down very fast. The glue will keep it's strength longer if you use it at a lower temperature. The drawback is that the working time will be shorter, unless you use some sort of pre-heat or post-heat. A lot depends on the temperature of the shop too. Higher gram strength glues gel quicker, so that's something to keep in mind.

In the old days they used to have a fire place at one end of the shop with a brick wall about 6-8 feet in front of it. This was where they did veneer work, and other operations that required longer working time with the glue. The radiant heat from the fire warmed the wall, so that was a nice hot spot. There are a number of tricks employed for extending the working time of HHG. One of my favorites is the way Torres is said to have glued his back bracing. He installed the braces in the liners, and arched them while the instrument was still on the solera. When it was time to glue on the braceless back he'd put glue on the braces and allow it to gel. Then he'd glue the back on around the edge, working in glue for a few inches at a time and clamping it. Once the edge of the back was down he'd use a paint brush to slop a bit of alcohol on the back where the braces were, and light it on fire. This would warm up the wood and melt the glue. They infer this in part from the fact that some of his guitars have darkened areas in the wood over the back braces, where he got a bit carried away with the alcohol.

Don Warnock used to use HHG for installing solid bent liners. He'd put glue on both the liner and the side, allow it to gel, and take his time clamping everything up with something like clothespins. He'd use a wide piece of dead soft aluminum on the outside of the sides as a caul, and see that it was fit pretty well. Once all the clamps were on he'd use a small alcohol fueled torch to warm the aluminum below the clamps, and watch to see when the glue liquefied.

Another trick is to paint HHG on both surfaces to be glued, and allow it to dry. The parts can then be clamped and aligned perfectly. Once everything is right you can remove some clamps, inject a bit of steam to re-activate the glue surface, and put the clamps back on. This is a great way to glue up something large, like a 'cello back, where you want things to align just right.

No discussion of HHG would be complete without a mention of 'rubbed joints'. Things get clamped for two reasons; to pull them into line when they don't fit right, and to squeeze out excess glue. We, of course, always make joints that fit perfectly, so we don't need a lot of force to pull them into line. Rubbing the parts together works just as well as clamping to get out excess glue, and doesn't introduce the sorts of distortions that clamps can. It's an especially useful technique for joining arched plates. Once the edges are perfect you clamp one side of the top or back in the vice with the glue surface up. Warm everything, and slop a goodly amount of hot glue on both surfaces. Place the other half on top of the piece in the vice, and rub it back and forth while applying some pressure to squeeze out the glue. At some point you'll feel it start to grab as the glue line gets thin. Slide the parts into alignment, and walk away. Some folks think this makes an inherently weak joint. Once, when I was demoing HHG to a friend I made a rub joint using a piece of brace stock. I planed off one surface to make it fresh and flat, cut the piece in two, applied glue, and rubbed them together. After they'd sat on the bench for only about fifteen minutes I clamped one side in the vice, and hit the other sideways with a hammer. I got 100% wood shear. It works.

[Simon Magennis]

…..
No discussion of HHG would be complete without a mention of ….

Frank Ford!
Intro:
http://www.frets.com/FretsPages/Luthier ... eglue.html


Ife you read nothing else read this sequence (2 pages):
http://www.frets.com/FretsPages/Luthier ... glue1.html

[Todd Stock]

Its worth pointing out that the water bath temp is going to be 10-15 deg F warmer than glue temp in a loosely-capped jar for Proctor Silex/Rival pots...150-155 degree F water temp (measured about 1" off the bottom with digital candy therm) generates about 135-140 deg F glue temp at the bottom of the jar. Hold-Heets with poly caps to allow water bath use show the same temp differential, so worth making some measurements when setting up your rig.

Also - if greater penetration into a joint to be repaired is needed (I have a Gibson neck joint waiting for me in the shop that is too tight for anything else) running a small amount of glue up to 170-180 degrees to get better penetration works well - just remember to toss the unused glue...there's some loss of strength, but nothing noticeable...until the next reheat, where there will be a very pronounced reduction in tack.

[Beate Ritzert]

Although this is a discussion on HHG, may i also bring Fish Glue into consideration?
Fish glue is in many aspects very similar to HHG, but in others it differs significantly. As You have read here, i have been using fish glue in two extensive repair projects, and my overall satisfaction is so good that i tend to use it as my standard glue and go to HHG only in applications where HHG is superior.

The most noticeable difference is that it is fluid at room temperature and that it can be used easily in those situations where HHG is difficult to apply.

Glueing strength is said to be comparable to that of HHG. There is also "Hausenblasenleim" - a very rare kind of fish glue, which is said to be the strongest of those glues.

I found it a bit difficult to thin it in order to let it flow into narrow breaks but possible after some experimenting. I did not try to warm it up although this should also decrease the viscosity of fish glue.

I did not try but i read that it was almost impossible to mix it with wooden dust to fill breaks - actually the demands on the precision of fitting of the surfaces seem to be (even) higher than with HHG? (That's meant as a question).

So let me sum up my question: how do HHG and fish glue relate? What are the pros and cons of the two?

[Todd Stock]

I have been using fish since 2007. Key differences are:

- Longer drying time
- Longer clamp time and more precise fit needed
- Tougher clean-up, but still easier than Titebond
- Heat release is a little more difficult...hide seems more predictable.
- Drying glue, so new fish glue bonds with old/dry fish glue
- Sensitive to high humidity...I don't use it where the joint will be open to air...

I use fish for binding and purfling, although it also works as well for fretboards, head plates, and other large, minimally loaded laminations. I consider hide to be superior for anything load-bearing and not completely sealed, and never use it on bridges or other highly stressed assemblies.

[Beate Ritzert]

I found fish glue very sensitive to acetic acid, which makes opening relatively easy in case of difficulties. But the acid can also discolor the wood, can't it?

[Todd Stock]

Acetic acid works for Titebond, fish, and hide - pretty much any AR/PVA or drying animal glue...the commercially available De-Glu-Goo glue remover is gelled acetic acid, and is very handy for vertical surfaces (otherwise, soak a paper towel with white vinegar - dilute acetic acid - and place on the glue to be removed). A good rise with distilled water to remove any acid is necessary prior to finishing.

On staining - with what woods are you seeing staining? Woods high in tannic acid (oak, cherry, walnut, other fruit or nut trees, and some mahogany) can see a reaction with tap water that has a high iron content (common in the well water here, for instance) resulting in what is commonly referred to as 'iron staining'...a dark, grey stain containing ferric oxide (Fe III). The common fix for iron stains on wood is to use oxalic acid as a donor of electrons to convert the iron tannates to a colorless chemical complex easily soluble in water. A thorough rinse in distilled water removes any remaining acid or iron. Oxalic acid is a common hardware store item packaged both as dry crystals or as a component in liquid 'wood brighteners'...look for oxalic acid as the active ingredient in single-part packaged wood bleaches...it does not actually lighten or change the color of wood, but instead removes iron stains and other oxides.

[Alan Carruth]

Acetic acid reacts with iron to form ferric acetate, a clear liquid. This can take some time. Ferric acetate and tannin react to form a black iron oxide (like magnetite?) in the wood. This is the traditional black stain, and still one of the best, as it's permanent. When using acetic acid to disassemble glue joints use a stainless steel knife rather than a carbon steel one, or you WILL end up with black stains.

I was given some methyl-cellulose powder by a student who worked with the museum restoration folks from time to time. You mix it with the acetic acid solution to form a gel, which keeps the stuff where you want it and slows evaporation. That's probably close to what the commercial glue removers are.

Photographer's stop bath is a strong acetic acid, 28% or so, iirc. It works much quicker than regular household vinegar. There is also 'agricultural vinegar' that's up around 10% concentration, I'm told, as opposed to the 3% for household stuff.

"Hausenblasenleim". Is that the glue that's made from sturgeon swim bladders? I was given a bag of those by a Russian maker who got them from a friend in the caviar business. You use it pretty much like normal hide glue. Soak the bladder material in cold water for several hours and then heat it. There will be some insoluble membrane that you have to fish out and discard. The resulting glue is almost water clear, which is why it's the favorite for gesso work that is going to be guilt. It is said to be stronger and more heat resistant than normal hide glue. It also smells like the place under the dock after the party fishing boat has come in.