When I designed the Hillbilly Tansu, I made a concerted effort to make it modular. Even so, it became apparent that glue-ups would be challenging. Lots of joints needed to be seated with each stage of construction. Experience tells me that the ubiquitous yellow wood glue requires speed in these types of glue-ups. If you’ve ever experienced joint “freeze” in the middle of an assembly, you know what I’m talking about. I actually considered going the traditional Japanese route and use rice glue. It’s easy to make but needs to be made before every gluing session. That’s not going to happen in my shop. There is no way I could plan my limited time in the shop to include cooking rice and mashing it into paste. So a little bit of research and the overwhelming solution seamed to be liquid hide glue.
I’ve read about, watched videos but never used hot hide glue. Animal bits soaked and cooked in a double boiler creating, by all accounts distinctive smelling, amber glue. But this stuff sets up quicker than our friend yellow glue. In fact, that is one of the advantages of hot hide glue. It’s highly recommended for operations where you want the parts to stick together as quickly as possible. Panel assemblies and veneer work top this list of applications for hot hide glue. I knew liquid hide glue existed but never gave it much thought. I was generally happy with the yellow glue that I had been using and I wrongly assumed that the liquid version behaved just as the hot version. Not so.
Liquid hide glue is, in fact, hot hid glue but with the addition of urea. The added urea causes the glue to remain liquid at room temperature or slightly higher. The other thing that the urea does is retard the set time. Now the setup and cure is determined by evaporation or absorption of the glues water content resulting in a longer working/open time. Inside the joint the wood absorbs the water. Any squeeze out relies on evaporation. This means that any thicker globs of squeeze out could take days to dry. So you will want to address any squeeze out during the assembly.
There are two options that are available for purchase on the market. Titbond and Old Brown Glue. Essentially these two are the same. The main differences being that the Titebond version is liquid at room temperature and widely available and Old Brown Glue needs to heated above 140deg to obtain a liquid state and may be more difficult to locate, although this seems to be changing. Strength and open time for the two are almost identical. Popular Woodworking did a side-by-side comparison of the two and detailed the results. You can read that article here. An additional feature of liquid hide glue to note is that it is reversible by applying heat and water. If you make an error during assembly, you have the option of taking it back apart. Years down the road if something is damaged, you can disassemble, make repairs and then glue the assembly back together. Which brings up a disadvantage. High moisture and heat areas are not good locations for items that are assembled with hide glue. Bathrooms, kitchens and anything out-of-doors. The liquid hide glue from both manufacturers has a shelf life. So be sure to check the date on the container before you purchase.
My local Woodcraft carries both brands of liquid hide glue and in the end I chose to go with the Titebond product. I made this decision solely on the fact that it is ready straight out of the bottle at room temperature. I didn’t want the added complication of having to heat the Old Brown Glue before using it. I also picked up a couple other items to make my glue-up go a little smoother. Up to this point I have always used yellow glue straight from the bottle. Squeeze out a dollop on the joint and distribute the glue with a scrap of wood that was roughly shaped for the task. I decided that a little more sophistication was in order and purchased a silicon glue tray and a package of glue brushes. Woodcraft actually sells two different glue trays. One touted for brushes the other for rollers. The one for brushes seemed too deep and the sides too flexible, so I opted for the one designed for glue rollers. Works great. The glue stays in a puddle at the bottom and the brush lies on the ramp. Wet glue washes off easily and dried glue will just peel free from the silicone. The brushes are sold as disposable but, since hide glue will dissolve in water, I just give them a soak and a rinse and they are ready to go again.
I wish that I had tried liquid hide glue before now. The extended working time has greatly reduced my stress level during glue-ups. Plus there is the added comfort of knowing that I can take something back apart in the event of a major malfunction. I find it much easier to control the application of liquid hide glue as opposed to yellow glue. The liquid hide glue has a thicker consistency and stays where I put it. No runs or drips. Clean up is easy as well. I have yet to experience any joint freeze while using the liquid hid glue. Even on my most time-consuming assembly that ran at least 30 minutes. In fact, I feel that the liquid hide glue adds a measure of lubrication. Joints go together easier than when they were dry and gentle clamp pressure is all that is needed to fully seat them.
Will liquid hide glue completely replace yellow glue in my shop? Probably not, but yellow glue will see limited use from now on. I’m completely satisfied with the Titebod liquid hide glue, but may give the Old Brown Glue version a try when I need to replenish my supplies. If for no other reason than to support a small American company.