Quick Tip #13: Don’t Fear the Hide Glue

It’s Get Woodworking Week 2013, and that means that it’s time once again to do our part to promote woodworking and grow the craft. Of course this should be a year long activity, but this week, we really focus on newcomers and rank beginners to the craft. Today, I want to talk about an often misunderstood part of traditional woodworking, hot hide glue. Contrary to what some would have us believe, hot hide glue is not complicated to use and is actually very forgiving. You also don’t need expensive glue pots to use it. You can of course buy one, and they do work wonderfully well, but you shouldn’t think that they are necessary to use this glue. In fact, you can get started with little more expense than the glue itself. An empty jelly jar heated in a sauce pan of water on the stove top will work just fine. You can also use an inexpensive hot pot and an empty glass jar, an old cast iron glue pot like I use (about $10 on ebay), and any number of other creative solutions to heat the glue. Whatever you choose to use to heat it, here’s how to go about it.


 

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19 thoughts on “Quick Tip #13: Don’t Fear the Hide Glue

  1. Hey Bob-
    As a newbie (building my own tools and bench now when I have the time), I’ve found your site very informative and enjoyable since I stumbled upon it around the New Year. Your passion for your craft and willingness (especially Get Woodworking Week) to share your experiences and insight are much appreciated. Continued success to you and thank you for all you do.

    Nick

    • I use the same pot as Leif, but didn’t think to insulate the lid. I just cut two holes in it, one for the glue brush and one for the thermometer. I use a candy and oil thermometer, but some of them are more fragile than meat thermometers. Make sure the hide glue doesn’t go over 150°. If it does, it cooks, and that ruins it. 140° is about the right temperature to keep the glue.

      One more advantage of hide glue: Quick clean-up by shop dog!

    • what are the different characteristics of hot & liquid hide glue? Why would one use each? Thanks, Ryc

      • Ryc,
        To expand on what Sam says, hot and liquid hide glues are more or less the same thing. The main difference is that the liquid version has additives that allow it to remain liquid, or very close to liquid, at normal room temperature. These additives can be anything from urea to salt. Their main goal is to prevent the glue from geling in the bottle. The additives give liquid hide glue a very long open time. You have 20-25 minutes of open time with the liquid version compared to just a couple of minutes of open time with the hot version. The down side is that the additives also weaken the glue somewhat. They don’t weaken it enough to be concerning for most of the work we do. However, if you build things that put a lot of stress on the glue joints, like stringed instruments, which are under extremely high tensions, then you don’t want to use the liquid product.

        “Liquid” is also a bit of a misnomer. At 70 degrees and up, this stuff flows pretty well. However, if you work in a garage, you will find that below about 65 degrees, the stuff starts to thicken considrably, and won’t flow well. So you will need to warm the bottle in a container of hot tap water to get it flowing again.

        I use liquid the majority of the time primarily for the convenience. The additives help to keep the glue from spoiling longer (though it still has an expiration date) and also allow one to use it like PVA. Just open the bottle, squeeze it on and go. The liquid is strong enough for all but the most stressful of connections (i.e. high tension joints), it cleans up with water, is just as transparent to finishes as the hot, and is more convenient to use.

        The hot hide glue is magical stuff though. While it has a much shorter open time, its not so short as to be stressful as long as you plan your assemblies out before you start brushing on the glue. The wonderful thing about hot hide glue is that it requires no clamps. This is typically the stressful part of the assembly, getting the clamps on and getting things clamped up before the PVA glue grabs too much to allow you to close the joint. When you can eliminate the stressful application of clamps, it takes a lot of the stress out of the equation. You do need to make sure your joinery dry fits well and closes tight with hand pressure or light mallet blows only. It should also not require a hydraulic press to disassemble. Once you are sure your dry fit is good, glue up one joint at a time. Hold it tightly closed for 30 seconds to a minute and you’re done. The grab of the glue as it cools will prevent the joint from opening back up. And, because hide glue shrinks as it cools and dries, it will actually pull the joint tighter together as it dries, no clamps necessary. Obviously it won’t close up a gappy joint. The joint needs to fit well during dry assembly. But it shrinks enough to keep the joint tight as it dries. This allows you to do things like rub joints, hammer veneering, or assemble a dovetailed case, without clamps. Just glue, assemble, square the case up, and walk away as it dries, again, no clamps necessary. Or rub on some glue blocks for attaching a table top and have them stay in place and dry without clamping. It’s awesome stuff, and in dry form, it basically has an infinite shelf life.

        Both glues are also reversible, though this is not always easy. On an edge joint like a panel glue up, it’s fairly easy. On an exposed dovetail joint, it’s a little tougher, but still fairly easy as long as the joint is wet and hot enough. On a mortise & tenon, you can almost forget about it. It’s very hard to get enough moisture in the joint to soften the glue once it’s dry. If it’s not fully dried yet, the application of a good amount of heat may soften the glue inside the joint up enough to disassemble it, but mortise & tenon joints are tough to take apart.

  2. Check out La Grande / La Petite Wax Warmer the larger unit at 4 oz is great for hot hide glue which is what I use.

    Has a lid, Has a thermostat which you can calibrate and mark for the 145 degree optimum heat level for hot hide glue. Just add a small jar of ur oYou can pick them up for around $24… Amazon had them the last time I had checked. Picked his up from another website awhile back.

  3. To Ryc Williams:
    The thing about cooking your own glue, from granules, is it has a relatively short working time, hide glue bonds through heat and moisture loss, the liquid form of the glue, Old Brown Glue, still all natural, has been formulated to provide a much longer open, or working time. I find it extremely helpful in larger glue ups, and complex joinery assembly. However, a “rubbed” bond with no clamps at all can be achieved using cooked/hot protein glue, it bonds that fast. and both are totally reversible.

    Thanks, Sam

  4. Hi Bob,
    Thanks for this video. I’m a relatively new woodworker who has benefited greatly from all your podcasts. Unfortunately where I am (New Zealand) we don’t have any hide glue retailers (unless you count a local manufacturer that will sell you a 25kg bucket) and between various export/import restrictions and shipping costs it gets a bit ridiculous trying to bring some in from overseas.
    I have managed to find a local source for a gelatine adhesive with 125g bloom strength (data sheet is aimed at food industry) used in conservation work and was wondering if this would do the trick ? From what I have been able to read the only downside would be the extended open time but even the lower strength hide glues are stronger than the wood ? Or is there a reliable way to test it bearing in mind that I have never used hide glue so don’t know what to expect ?

    Appreciate your thoughts and thanks for all the effort you put into your videos

    cheers
    Robin

    • Robin,
      The lower strength hide glues are fine. I use 192 gram strength almost exclusively and it works great. The other thing you can look for in your grocery store is unflavored, plain Knox gelatine (or other brand). It has to be the kind that is just gelatine though with none of the sugar flavorings and what not. Believe it or not, the plain, unflavored, amber colored gelatine that you can find in the grocery store is really nothing more than hide glue that has been more refined and purified to make it fit for consumption. Try it out, it works.

  5. Hi,
    First off all I really like you’re blog. I learned a lot from it.
    I have been using hide glue for a while now.
    Just a quick tip: I use a baby botle warmer. It hase a thermeostat and everything. It works greate.

    A question. I read that it’s is not good to use a brush that has mettal parts in it why is that?

  6. lots of ferrous metals are used to make brush ferrules. The iron will turn your hide glue black, and render it useless, traditionally a string wrapped hog bristle brush was used. The Violin Center has two offerings for glue brushes, hog bristle, string wrapped, and a linden tree brush, you just keep bashing the linden limb, until it’s all used up. I use a regular old natural bristle paint brush and just wrap masking tape around the ferrule.

    Sam

    • Sam,

      Do you think horsetail (Equus, not Equisetum), instead of hog bristle, would be effective?

      Do you think I would have compatibility problems with a brass ferrule instead of steel?

  7. Finally cooked a batch of hide glue. Pot worked flawlessly. Not having to use clamps was a huge timesaver. I was doing a lot of simple rub glue block type joints. As the glue hardened, I would scrape off the squeeze out. It was in semi soft strings like worms. Cat I put these back in the pot? Should the left over glue in the pot at the end of the day go in the fridge or freezer? Is it ok to use hot water to soak the granule of hide glue?

    Bob, thank you for taking the time to host this blog/podcast !!!

    • I put the scraped off glue back in the pot. Some people don’t, fearing it weakens the rest of the pot. I’ve never noticed any weakening, and I’ve read that it was done historically.

      For the leftover glue, I put it in the refrigerator and use it until it shows signs of getting moldy. This usually takes a week or two. But I really try to only mix up what I need so I don’t have a lot of leftover glue that I need to store. If I need glue on consecutive days, I’ll cook a bigger batch, but usually it’s only about a tablespoon or two of glue that I need to cook up for a small glue up.

      You can use hot water to mix the glue. It doesn’t really make the process much faster though. The glue still needs to absorb the water before you start cooking it.

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