"Commercial liquid hide glues have gel suppressants (Ed: like urea or thiourea) & remain liquid at room temperature. They are not quite as useful for most instrument work: slightly greater tendency for the joint to “creep,” lower moisture & heat resistance, short shelf life, no initial tack. Many instrument makers and repairers use liquid hide glue, but they are (or should be) careful to test each batch, in addition to watching the expiration date printed on the bottle.
Urea will extend the working time of the glue, and will not weaken the adhesion if it is mixed with the glue just before use. More than 5-10% urea (by dry weight) may increase the flexibility of the dried glue; it may allow glue joints to “creep” more, especially in heat stress. Most instrument builders and repairers try to avoid having to use urea."
Hope this helps. I personally use the stuff that Frank uses, the Milligan and Higgins 192 gram strength high clarity dry granules. Works great, sticks good, cleans up easy, and otherwise is like nasal exudate. Every silver lining has a cloud.
As I write this, though, it occurs to me that there is one instrument application that the liquid hide glue might be perfect for and that's glueing wood bindings and purflings. I currently use hot hide glue because I get the best finished joints with it but I know that alot of builders tend to use Original Titebond aliphatic glue for this just to get the extra open joint time that I don't get with the hot glue. Maybe this could be a niche for the liquid hide glue because it would have better open joint time and still draw up the glue joints like hot glue would.
I put a fiddle together a few years ago with Franklin Liquid Hide Glue and it came apart in the summer when the temperature got above 75 deg F. The glue just never dried. Liquid hide glue has a shelf life beyond which apparently it breaks down. The bottle I used was well within the "use by..." date but still was bad. Based on that experience, I wouldnt recommend any liquid hide glue....caveat emptor.
I can attest to this. I had some really great help with guitar #2, but not a lot going for #1 except for Cumpiano's book. When speaking with a wood-worker at the local quality tool store I was told liquid hide glue by Titebond was the best and that it would hold anything. The minute I moved to a place where the house wasn't at a constant 70 degrees (I think the air conditioning was set at 77 to save some cash) it started failing dramatically. I was actually sitting in the room one day and heard a pop. I looked over and the bridge had pulled off. The next day the end graft fell out and in the following days the ribs seperated and part of the top came up. It was pretty crazy. And, I know it wasn't humidity because the instruments are stored at in a humidified room, and none of the others have had problems since using titebond I
I've never used it but have heard bad reports from just about everyone that I have talked to, that has used it.
If you want to use hide glue stick with the old fashioned kind that you buy in granular form and mix with water and heat.
Original Tite-bond, which is an alaphatic resin glue, is a great glue too.
One option if you want to stay with a collagen glue would be fish glue. It has a long open time, less initial
tack than HHG but allows for much more working time. It's biggest draw-back is that it's more hygroscopic
than HHG and could be a problem in really high humidity situations. I've used it for quite a while in fairly high
humidity conditions (60-70%RH) and never had a problem. I don't like to work in those conditions but sometimes
find it impossible to lower the RH... I would think that if you used it, the ideal would
be to glue the bridge and neck joints with HHG and the rest with fish glue. With practice,however, you
can use HHG as a one-person operation with well-planned gluing operations.
Mark, it is a very old glue, often preferred for furniture repair over HHG because it has a long open time,
up to one hour. It's a high-tack glue, same ph range as HHG, 3200psi shear strength, can be repaired like HHG with heat and moisture, then re-application of the glue. It also shrinks as it sets so it will pull a joint together, like HHG.
I know one source of the glue is the Sturgeon, though it may come from other fish as well. It smells no better than HHG, is best stored in a sealed container in the fridge and stored in small bottles when in use.
Many furniture restorers won't talk about any other glue, it's all they use. Makes sense since many times they are gluing some pretty large joints. I think it has a role in our field as well and am trying to find it's limits and best uses now. Seems promising, just finished a guitar where every joint is glued with fish glue. We'll see.
Bruce, are you using one of the commercially available liquid fish glue products or prepping your glue from the powder and using it hot? Would love to know more and also to hear how things work out with the guitar.
Bob, I get my fish glue from the Olde Mill Cabinet Shoppe in York, PA. They sell it in quarts and gallons and it seems that most of their customers are furniture repair people. I was looking for something that would perform like HHG and yet allow me the luxury of time.
I'm just not that organized I guess, and gluing top and backs onto rims is a real stretch for me using HHG. I like the properties of HHG and fish glue seems to provide at least some of them.
Maybe more than other glues. I've removed some joints for other reasons and had them react exactly like HHG joints. I think many folks who use HHG like the quick initial tack they get, you do not get that with fish glue and you need to be ready for some movement. That's not that difficult to overcome of course, but it is a factor. Not as much as and aliphatic resin glue however. It is slightly more difficult to clean up than HHG, can't say why. Seems like with HHG one wipe with a moist paper towel or cotton tip and you're done. This glue takes a couple of passes to really clean up. When dry, it chips off just like HHG but you do get a healthy respect for it's strength.
I like it and will continue to use it, one guitar completely glued with it and a few others with various sections glued with it. I'm going to keep using it and see what I find. I'd encourage anyone to give it a try. The one recommendation you find with fish glue is to not use it on outdoor furniture or other items exposed to high humidity. I suspect this is due to its
hygroscopic properties. I've never noticed this in anything I've worked with.
Hopefully, I won't have much to report, no lifting bridges or loose braces....