Bottled hide glue

[Roger Bell]

I want to repair some loose stretchers in a very old rocker and want to use hide glue.

Is there any essential difference between the mix-your-own and the bottled stuff from Titebond? And, if so, what is the significance of the difference(s)?

[Dan Forman]

The bottled is generally considered to be stronger, or at least more consistent, than the home brewed. It takes longer to set, so you don't do rub joints with it, you need to clamp it. Other than that, my understanding is they are about the same.

Dan

[mike holden]

Roger,
I use bottled and the original hide glues. Essentially no difference, although, what I have read the bottled is slightly *less* strong, but it is not enough to care about.

Only advantage to bottled is longevity and ease of use (i.e. always ready), downside is that it is somewhat weaker, and takes much longer to set.

In your case, I would buy the bottled, and assuming the joint was originally done with hide glue, just run a damp rag over the existing glue to add just a bit of moisture, then add the bottled and clamp.

Neither version of hide glue will fill gaps with any strength though, so if the joint area is worn, you may have to add veneer shims or do some other form of reconstruction.

Mike

[Dan Forman]

Wood Magazine tested the liquid glue, and found it stronger than the stuff they made up themselves. I suppose there is room for variation due to prep techniques or quality of the dry granules. I guess I misspoke in my first reply, in that the reality may not be the general perception.

I did my own very unscientific test, and glued to pieces of wood together, then broke them apart with a hammer, and the wood failed rather than the glue. That was good enough for me. Other benefits: the slow setup time can be an advantage for complicated assemblies, the joints are repairable, and the squeeze-out can be cleaned up with water, without interfering with the finish. Just don't use it for an Adirondack chair. :D

One thing to be aware of, is that there is an expiration date on the bottles, best to check that to make sure it is fresh.

Dan

[mike holden]

Dan,
Trying to extrapolate from a single test to the great variety of woods is a chancy thing.
As a chemist, I can say that the urea added to the hide glue to extend its liquid phase, will, if nothing else, take up some room in the mixture. Following the TANSTAAFL principle, less glue in the joint means less adhesion (theoretically).
Hide glues are available in a range of gram strengths.
The lignin which adheres wood fibers to themselves (the natural tree product) varies substantially within a single board from area to area.
The variables in the wood itself are simply larger than the variation between the glues.
In the original posters request, either hide glue would be stronger than required, assuming a close fit between parts.
This is like determining the number of angels that can dance on the head of a pin. Pointless and immaterial.
Hide glue works, whether poured from a bottle or brushed on from a hot glue pot.

What is important here, is that if the original glue was a hide glue, than there is no need to clean the joint down to bare wood to attain adhesion with additional hide glue. Something that no pva (polyvinylacetate) glue can claim.

Pax, Mike

[george wilson]

Mike,FWW also did a glue test,and found the bottled glue stronger,which surprised me too. Maybe you are over looking a factor such as the urea making the glue tougher and less brittle than cooked glue. I suspect the bottled glue is tougher,from the way the 2 feel when you try to get rid of dry spurt out. The bottled glue feels less easy to shatter off,if you see what I mean.

You can also make cooked glue tougher by adding a little glycerine. It might actually be better for joints in chairs that way.

[Dan Forman]

Mike---I guess I could have been more clear. I wasn't really trying to argue for the superiority of the bottled glue, but against the popular notion that bottled is inferior to user mixed. Each have characteristics which can be advantageous for particular situations.

The other advantages I mentioned were for the bottled hide glue over PVA glues, not powdered hide glue. So basically we are on the same page.

Oh, and the angel thing, 4 is the max, otherwise they start bumping into one another, and the language that ensues makes them seem less angelic. :D

Dan