Hide glue Rub Joints ?

[Doug Shepard]

I've got some small stuff to glue up that will be difficult to clamp due to odd angles and thinness of material (only 5/16"). All the joints are edge grain but various angle bevels. I think this may be a good opportunity to try out the vaunted rub-joint with hide glue, so I can just "clamp" with hand pressure. But for the size of this project I'd sort of like to avoid splurging for an electric glue pot and the hassle of mixing up the glue. Can you also do rub-joints with the bottled hide-glue? Or is it only the cooling of heated hide-glue that lets you do the rub-joints?

[Jerry Olexa]

I'm in a similiar quandry. Getting ready to glue up odd angled, curved cherry w no place to clamp. I plan to use hide glue also and remoce the temporary braces later. Will the bottled work??

[Cliff Rohrabacher]

It may be useful.

http://www.sawmillcreek.org/showthread.php?t=33303&highlight=hide+cow%27s

[Jerry Olexa]

Cliff: Thank you. Very useful/helpful info. Hide glue really does have some advantages over the modern glues. I'll use on this glueup. Thanks again

[Steve Schoene]

A small slow cooker works quite well for a glue pot. You likely already have one, used ones are widely available--check the local Goodwill--and even if you get a brand new one it won't set you back very much. But, the rubbed joints really do work, and hot hide glue is AT LEAST as strong as commercial PVA or Polyurethane glues except if you keep them wet.

Note: use the cooker as a water bath, with the mixed up glue in a glass jar--no clean up problem, and you can put left overs in the fridge for a while.

[Chris Barton]

I use hide glues frequently and hot pots can be made from a variety of old appliances. I have a rice cooker that I bought new for $10 that is a great glue pot and as Steve points out, a small crock pot/slow cooker works perfectly.

[Doug Shepard]

Cliff - Thanks for the links. I read through them and it looks like the liquid hide glue probably wont do the rub joints. Looks like it's time to go crock-pot shopping.

[Alan Turner]

Hey guys, don't back off from the hot stuff. Once you get used to using it, it is hard to go back for many applications, beyond just the knee block on a cabriole leg. Hide gle won't stain your work, and so for dovetails, where squeeze out is always present, it is perfect. Hide glue is also gap filling.

One tip: it does dry by evaporation, and inside a joint this can take a while. For final drying, 24 hours is usually safe, but not always, depending.

If you tend to wait till the last minute to do things, then cook up batches of hide glue, put them in small jars in the beer cooler, and then just grab one when you need it. No need to do anything but heat it up. I have had hide glue in this form last for well over one year without incident, although this is longer than is usually recommended.

I have no comment on the cold stuff as I have not used it.

[Cliff Rohrabacher]

Yah I found those links very informative. So much so in fact that I think I'm going to start trelying on hide for more critical applications. I found expecially interesting the notion that polymer glues will deform under strady load and eventually release. His logic was that polymer glues bond on the mechanical level and are highly flexible being plastics to start with. This is, of course, exactly true. Then he deduces that the plastic will flow under a constant load. Also true. Plastics don't need stress so great as to to overwhelm their hysterisis strength to induce a flow. The critical factors I think are the amount of stress, the amount of flow, and the time required to get a destructive level of flow.

We use epoxies in high stress applications like aircraft and boats. We tell ourselves that the epoxy is designed to last 30 years and compare that to the expected lifespan of the vessle. Yet we keep those structures in commercial and civilian operation long beyond 30 years.
So then, what will happen to those Boeings and AirBusses when the life span of the epoxies is Kaput??
I bet they will keep 'em in the air till the number of planes that fall apart gets too great to bear.

However, in point of fact ALL materials are plastic on some level. All materials flow. I have seen a nanometer size hole that was laser drilled in a piece of ceramic that was then placed under a Scanning Tunneling Electron Miscroscope. The hole was fluid. It moved and changed shape constantly while under no induced stress.

That same author (on the Hide glue) believes that the organic glue establishes a chemical bond with the wood. That'd require a covalent bonding. Of course that is not at all out of the question as they are all carbon based organics and carbon based molecules almost always have a valence shell somewhwere that can accept another bonding.

It was all very interesting.
So I am going to try hide glues.

[Howard Acheson]

I think you will find that you can rub glue with PVA adhesive just fine. Try it on some scrap.

[Chris Fite]

I have made rub joints with Titebond, and it worked fine.

[Howard Acheson]

Let me suggest that hide glue has a number of good points. It does provide a very secure joint and has excellent shear strength. However, it's shear strength is why it does not made a good, long lasting adhesive for cross grain joints like mortise and tenon or most of the joints on chairs. Chairs are under continuous but changing stresses and an inflexible, brittle adhesive like hide glue cracks causing joints to loosen and fail.

A PVA adhesive is a more flexible adhesive. True, it does not have the shear strength of hide glue (or casein or urea formaldehyde but it will maintain it's integrety in a cross grain joint because it will sort of "stretch" with cross grain movement of wood.

Chairs are best glued with slow set, two part epoxy. It too, is a somewhat flexible adhesive and chair joints will maintain their integrety must longer when epoxy is used.

Going back to the original query, rub joints can be done with almost all adhesives.

[Doug Shepard]

...
Going back to the original query, rub joints can be done with almost all adhesives.

Howard. Thanks for all the input. I realize I can use any glue and rub 2 surfaces back and forth until it starts to get tacky if that's the definition of a rub-joint. Maybe I wasn't asking the right question. Based on what I've read about hide glue, I'm under the impression that it's the only one that really sets firmly enough quickly that you can skip clamping and just use hand pressure to hold the joint then set it aside to cure overnight after the initial quick-set. In all the attached links in the earlier replies I dont see anything that specifically says the liquid hide glue will (or won't) do this. In all those links the only glue I see this "rub-joint" property mentioned with is the heated hide glue. Maybe it's a case of using a mis-leading definition? Maybe I should be asking what the advantage is of using hot hide glue vs. an electric glue stick gun if the no-clamp/fast-set effect is really what I'm looking for??

[Reg Mitchell]

I too read those articals, and if i rmember it correctly you can usa addatives and make the hide glue flexable also.....or did I dream that .....gawddddddddddd these 12 hr days ar inhuman :eek: