Tuesday, April 1, 2014

The perfect glue - Liquid hide glue success!

Home brew

I have been becoming ever more dissatisfied with store bought glue. I dont know if it just stems from decades of daily epoxy usage or what. Having a hardcore yacht renovation avocation tends to make one an expert in the use of a multitude of sticky goops, but for me it was a necessary evil. Now that I don't HAVE to use glue for everything, I am really beginning to hate the stuff.

From a general woodworking perspective, my experience is almost exclusively with using the standard "yellow" glues. It's strengths lie in its.....strengths. And it just gets better and better. The new yellow glues are much stronger than the glues of 30 years ago, with good wetting ability, quick grab, and a short time-to-use interval. But woe is he who needs to adjust for square or realizes he has made an error (What, still too short?!!). Or, God forbid, apply a finish. You might notice that the stuff is called "Carpenter's" glue, not "Cabinetmaker's" glue.

I tend to error on the side of "too much", so cleaning up squeeze out occupies a fair bit of my project time. No matter how good a job I do, there are always spots that I've missed, or areas that have absorbed enough glue that it affects the penetration of stains or oils, leaving a miscolored smear. So I mask joints with tape, or paste wax, or pray, whatever works. YRMV....

An ideal would be to not require glue at all and just rely on joinery but, alas, I'm not THAT good. Also, over time, even the tightest of joints will work in service, becoming loose and making that distinctive *Creak* that our kitchen chairs make. Glue has been used throughout human history to stabilize joinery, so I try not to feel TOO bad about my minimal usage.

The perfect glue for woodworking is:

  • waterproof
  • works in all temperatures
  • has strength in excess of the wood being joined
  • will fully wet the joint without draining away
  • be transparent to finishes and 
  • be reversible at some time in the future.
It also doesn't exist. You need to prioritize.

I am late to the 'ol hide glue party, but better late than never, I suppose. Hide glue....... How is it that it took so long for us to meet? Hide glue meets nearly all of the above criteria, with the exception of waterproof and temperature sensitivity. Still, these two weaknesses can be improved.

Alum added to hide glue will evidently improve the water resistance of his glue. I haven't adequately tested this yet, so I will refrain from too much comment. I suspect that "water resistant" will be the result, which would be good enough for me. Now that I mention it......*wheels turning*....

Hide glue is used hot (140°F), and has a very short open time at colder temps (which means all year, here on the Oregon coast). I need liquid hide glue. Patrick Edwards's Old Brown Glue (OBG) is the gold standard, with Franklin liquid hide glue being the only other option commonly available. Neither of these exist in my town, so I have been trying to make my own liquid hide glue.

Granular hide glue can be made liquid by the addition of one of two ingredients, either Urea or salt. I haven't found Urea yet, so...... Salt it is. And it hasn't worked. The resulting blend has still become a gelatinous blob at room temperature, only increasing the working time by maybe 20% or so. I need a new recipe.

I finally found this article about liquid hide glue (and a recipe!) in  Popular Woodworking. The source of the recipe is Don Williams, the senior furniture conservator at the Smithsonian's Museum Conservation Institute. I would trust those credentials. The recipe uses three very basic ingredients: salt, granular hide glue, and water. The ratio is easy to remember: 1:2:3. I like simple recipes. Simple is good.

I used a 1/4 measure, so this means 1/4 salt, 2/4 hide glue granules, 3/4 water. This glue is 260# Bloom gram strength from Lee Valley Tools.

Mix the hide glue and water together. Leave out the salt, for now. Let the mix sit overnight. I put mine in a 1qt jar.

The next day, add the salt, then heat the jar of goop in the glue pot of your choice at 140°-150° for 2 hours. I use a $10 dollar Crock Pot that I bought at Walmart. The "warm" setting is perfect for hot hide glue.

After 2 hours, put the mix in the refrigerator overnight (Important!). Evidently the quick cooling is key, because up till now, this is what I had always done and it hadn't made a big difference.

The next day my mix looked like meat jello, same as always. But hang in there. Heat the goop for another 2 hours at 140°-150°. This time is for real. Liquid hide glue! 

Room temp success. The salt will act as a preservative, too. I would normally make a much smaller batch, but I've got some bigger projects in the works and expect to use this reasonably quick. 

Little stuff first. 

Mouth repair insert on a naga-dai kanna (joiner plane).

Replacing a steel bolt with a wooden dowel in same, and gluing in a thin wooden slip, to tighten a loose bladed spokeshave. 

Works great. 1 pound of glue ($15) will make about 4 of these (16 oz?) bottles. I'm sure that this glue isn't any better that the Edward's OBG, but it sure is cheaper. Joel, at Tools For Working Wood, has both the OBG and granular hide glue. Buy from him, he's a great guy. And cheaper than the other guys, too.

No comments:

Post a Comment

Like all of us, I am figuring this out as I go, so when you see something that is incorrect or flat out wrong (and you will!), let me know. This is a learning process. Real people and names, please. Constructive comments and questions are very welcome, but hate speak/politics are not! Life (get one!) is too short.

Thanks, Jason