Advantages of hide glue?

[Paul Hingco]

I often see posts about this glue. What are it's advantages over PVA glue?

[mike holden]

Reversability, rub joints, does not show through finishes, hammer veneering, etc.
Downsides - glue prep time, some dont like the odor, lack of water resistance.

Mike

[russell lusthaus]

by applying heat, you can soften the glue, reposition the piece, and let dry in the new position.

Also, if gluing something like rawhide, the hide glue (made from rawhide scraps) will be the best glue, all other factors being equal - but not very weather (water) resistant.

If you want to say you used traditional materials, then Tite Bond would be out and Hide Glue in (but not the TB Hide Glue, as this is slightly different that actual hide glue).

I make bows, and quite often I will use hide glue to keep with the traditional aspect of the craft.

[Stephen Cherry]

http://www.pbs.org/woodwrightsshop/video/2800/2810.html

[Eddie Darby]

The reversibility of hide glue makes it ideal for musical instruments, that over a long service life, and sometimes hazardous one, need repairs that can be undone.
Cracks reopen and need to have the glue cleaned out before the seam can be rejoined and glued again.

The same goes for repairing Period Furniture, since restoration demands that whatever is done to a piece, it must be able to be undone.

Hide glue has no gap filling properties, so it requires wood-to-wood contact to be successful, and so demands more precision in making joints.

[Jim Matthews]

I recently took a class in Vermont where the director professed his admiration for hide glue as genuinely strong. His claim is that on any large glue up, there will be necessary adjustments while the joints are assembled.

His notion was that PVA glues form a "skin" when pieces are joined.
If the joint is moved (intentionally or by accident), adhesion is compromised.

His guesstimate was that 30-40% of the strength in a PVA bond is lost this way.

Because hide glue sets up more slowly, you get 100% of the strength from adhesion.

[Frank Drew]

I recently took a class in Vermont where the director professed his admiration for hide glue as genuinely strong. His claim is that on any large glue up, there will be necessary adjustments while the joints are assembled.

His notion was that PVA glues form a "skin" when pieces are joined.
If the joint is moved (intentionally or by accident), adhesion is compromised.

His guesstimate was that 30-40% of the strength in a PVA bond is lost this way.

Because hide glue sets up more slowly, you get 100% of the strength from adhesion.

Jim

I used hot glue (hide glue) exclusively for three years in my first job making furniture and I like it okay but chose not to use it as my main glue when I set up on my own. I don't agree with the director of that class you took; saying that hide glue sets up slowly is contrary to my experience with it; it works well for rub joints because it grabs fast, but that quick set makes subsequent adjustments problematic, much more so than with PVA/aliphatic resin glues like Elmer's or Titebond. Additionally, it has the shortest open time of any glue I've used, by far; once it chills it gels, and if that happens it won't work as a glue so you have to clean it off and start all over. In that regard it's a great glue for learning how to work really, really quickly.

[Jerry Olexa]

Easy to Un-do when you need to repair...

[Frank Drew]

Easy to Un-do when you need to repair... It is reversible (though not always so easily, such as with a mortise and tenon), but, realistically, how many times in the working life of a woodworker does he or she need to take apart a glue joint they made or otherwise repair their own work?

[Tony Bilello]

I recently took a class in Vermont where the director professed his admiration for hide glue.....
Because hide glue sets up more slowly, you get 100% of the strength from adhesion.

I believe the director never used hide glue or would not have made this statement. I don't recall the actual temp of the melted hide glue I used but I could tell you this... I was forced to buy a glue pot because back in the 1970's and 1980's a typical crock pot was too hot.
As soon as the glue starts to cool off, it is setting up. As a matter of fact, the fast set-up time can be a plus in chair assembly.
I used it a lot on restoring valuable antiques. On the not so valuable ones, I use PVA glue.

[george wilson]

No one seems to have mentioned that hide glue is the most time proven glue,having been in use for thousands of years.

[John Coloccia]

130 - 140 degrees is a good hide glue temperature.

re: advantages

-Hide glue will not creep under load. White and Yellow glue will creep. This may or not be important, depending on the kind of joint

-Hide glue has far better heat resistance although it will fail with an onslaught of heat and moisture.

-As others have mentioned, hide glue is reversible although white, yellow and epoxy can easily be made to release also with heat and/or moisture. Hide glue will happily reactivate and stick to itself whereas white and yellow glues bond poorly to old glue.

-hide accepts dye and stains. A slightly sloppy joint here and there will not be anywhere near as noticeable as if it were made with yellow glue

-hide glue reactivates with heat. This is supremely convenient for laminating veneers (just iron it down!). No clamps needed either...

-...no clamps needed often times :) The joint shrinks as it dries, drawing the parts in tighter. This is very convenient for veneering, reinforcement cleats, and other such things where clamping maybe either very inconvenient or practically impossible.

There's probably more I'm leaving out

disadvantages:

- ridiculously short open time. You need to work fast and/or change how you work. Warm shops, pre-heat parts with a hair dryer or heat gun, etc etc.

- the stupid mixing, heating and maintaining routine. It's a supreme pain in the tuckus. Very inconvenient unless you're using it all day, every day and are setup with a routine. If you just need to glue one or two things, it will take you longer to whip up a batch of hide glue than to grab some Titebond and actually do the stupid procedure.

- stinky? Meh...some people think so. I think it smells like chicken soup. If it smells really bad, it's probably old and moldy. It does smell like SOMETHING, though, so I guess that's a disadvantage

- It has practically ZERO gap filling ability. If you don't have a perfect joint, or near perfect at any rate, hide glue simply will not work well.

- You need a heating pot of some sort. These can cost upwards of $100+, or you'll have to cobble together your own and monitor it with a candy thermometer. Even the cheap homemade solutions will put you in the $30 range by the time you've purchased the pot and thermometer.

That's off the top of my head. It certainly makes sense for some things. Someone mentioned violins. The violin family instruments are designed to be taken apart and worked on. It makes less sense in a guitar where it's NOT designed to be disassembled, and any significant disassembly (like popping off a top) has so many other associated problems that the type of glue someone used is the least of your worries. Many think it makes sense for gluing on bridges. There are certain repairs where it makes sense because of the high likelihood of having to work on the repair again sometime in the future. Hot hide glue allows you to work right over the existing repair without having to clean anything out. A headstock crack comes to mind and a good place to use hide glue.

FWIW, I use Titebond II (recently switched from Titebond) and white glue when I need a little more time (Elmer's Glue All).

[Jim Matthews]

A clarification, perhaps...
http://www.titebond.com/ProductLineTB.asp?prodcat=2&prodline=5

Open time of ten minutes is double that of the original Titebond PVA.

I don't have any experience with glue pots, I use this stuff right out of the bottle.

If the assembly goes wrong, applied heat will allow repositioning the joint.

[Frank Drew]

Jim

That's not considered the "real" hide glue.

John,

Excellent summary of the pros and cons of hot glue.

[Arnold E Schnitzer]

As an instrument maker, I consider one of the most important features of hide glue to be its rigidity and hardness when cured. Compared to PVA and epoxy, hide (the real, hot glue) sets up really hard, making joints that are acoustically superior. I recently "converted" a guitar-maker friend to using hide instead of PVA. He is excited about it, believing that his new guitars sound and respond better.

[George Neill]

- Hide glue is worry free; you can slop it all over the shop with no fear of it resisting dye/stain. A quick wipe down with a hot cloth when all is done and any spills, drips or squeeze-out is removed. With PVA, you are always paranoid that you've missed a bit and it will spoil the finish. With the panic and worry factor removed, hide glue glue-ups can go quickly and smoothly.
- Hide glue open time can easily be extended well beyond that of PVA by the simple addition of a small quantity of urea or ordinary table salt.
- In its dry state, hide glue has an infinite shelf life, so you can buy it in bulk and save.
- The best glue pot I have ever owned is an electric wax pot. Wax pots can be bought on eBay, new, for as little as $28. The wax pot is more efficient than commercial glue pots; the glue can be brought up to working temperature in under 15 minutes which is hardly an inconvenience if you plan a head a little. With the tight fitting lid on a wax pot, glue will remain usable for at least a week.
- If only using the glue sporadically, any unused glue can be put in the freezer until next required.

[Larry Feltner]

Quick question. I've seen comments that liquid hide glue is not considered real hide glue. Aren't they exactly the same thing except liquid hide glue has urea added to it so it doesn't set up in the bottle?

[George Neill]

Correct, the commercial liquid hide glues that I'm aware of just contain urea. You can easily make your own. I occasionally make some from leftover hot glue rather than put it in the freezer.

[John Coloccia]

The problem with LHG, particularly Titebond's, is you really have no idea how the stuff has been handled and stored before you get it. I think Old Brown is a little better in this respect. You will get all the advantages and disadvantages of hide glue with urea in it (Old Brown, at any rate....I don't know what Titebond uses). Titebond is going to spend significant time being shipped in trailers, and things like that. It gets pretty hot in there on a summer day. 140 degrees plus? Maybe....I'm guessing so.

People have consistently had mixed results with Titebond's LHG for whatever reason. Sometimes it works great, and sometimes it's an issue. I don't know why. I do know that there are many complaints about failures, and certainly complaints about the glue staying sticky or becoming sticky and gummy under moderate heat.

I'm just trying to convey information I've collected. I don't know much about Titebond's version. I also don't read much bad....any bad, actually....about Old Brown.

[George Neill]

It's so simple to make; I don't understand why anyone would actually buy commercial liquid versions and run the risk of it being out of date or otherwise damaged.

[Federico Mena Quintero]

It's so simple to make; I don't understand why anyone would actually buy commercial liquid versions and run the risk of it being out of date or otherwise damaged.

How would one go about making some?

[George Neill]

Depending on the gram strength of your animal glue, adding 5-20% of urea by weight will create liquid glue. You can also use ordinary table salt to make liquid glue.



I would suggest you experiment with these additives to determine which works best for your glue/temperature/humidity.

[Federico Mena Quintero]

Depending on the gram strength of your animal glue, adding 5-20% of urea by weight will create liquid glue. You can also use ordinary table salt to make liquid glue.


Oh! I was asking about how to make hide glue itself. Sorry for the confusion.

[George Neill]

Oh! I was asking about how to make hide glue itself. Sorry for the confusion.

Ah OK; boil up some roadkill skin and bones then let it cool. Scoop off the fat and detritus and boil again. Clean the muck away for a second time and you will be left with gelatin – which is what animal glue is.

[Rich Engelhardt]

I don't recall what it was that sparked me to look for info on this topic.
It may actually have been this thread - since the thread is a couple of months old.

I ran across this real gem in the process of looking at hide glues/gelatin glues:

http://www.archive.org/stream/chemistrytechnol00bogurich#page/2/mode/2up

You can read or download the whole book.

I thought it was an interesting read - based on the perspective of old time honored glues vs what would have been the "new and improved" stuff - PVA, which was discovered in 1912. The copyright of the book is 1922.
While I don't recall seeing a direct reference to PVA, the author spends a lot of time and effort pointing out the sheer volume of sales/distribution/use of hide glues.

Anyhow - thought I'd share the link.

[Jerome Hanby]

All of my glue seems to be hide glue. Soon as I buy a new bottle, it stops hiding...