Sadly, hide glue is no longer an option for me due to the increase in humidity, moisture and heat in my part of the world. The glue is doing its job by reversing. Whatever the heat outside is it’s 10° hotter inside the workshop. I have Canadian poplar that’s bent like a banana thanks to the heat.
Amazon US
Amazon Australia
Disclaimer: As an Amazon Associate I earn from qualifying purchases.
Here is a glue application chart I obtained from woodsmith for your convenience to download. I can’t deny it’s accuracy, it’s pretty much spot on. You can also download my own chart I have compiled in my previous post.
I don’t claim I have all the answers and I don’t claim to be a teacher of any sort, my aim is only to pass on information I know and learn along the way. If it is of any benefit to you, then I have achieved my objective, but ultimately what you do with it is up to you.
Fish glue apparently was ordinarily available in the third century, since Hippolytus notes its use by magicians and diviners on the streets of Rome, in about 220 C.E. According to Hippolytus, fish glue had asbestos like properties, since the trickster “anoints his feet with fish glue” so that he can walk over hot coals without being burned.
A translation of Dioscorides of Anazarbus from an ancient Greek text of what fish glue is made from.
“Ichthyokolla is the stomach of a whale sized fish. The best kind is made in Pontus, and it is white, rather thick, and not scaly, and melts with a low heat (very rapidly). It is useful in making plasters for the head (skull fractures) and has properties appropriate for the treatment of Leprosies and in the manufacture of lotions that erase wrinkles from the face.”
Ladies, before you go out and slap fish glue over your faces note the translation reads “used in the manufacture of lotions” so obviously, there must be other agents mixed with it.
A Caspian fisherman who is presumed to be an eye witness, accounts in the making of fish glue and it’s workings:
“they take out the guts and boil them, and make from this a glue that is very useful, since it holds all things together quite firmly, and sticks to whatever it has been attached, and dries very shiny. And it binds everything that it holds and unites, so tightly that even if it is soaked in water for up to ten days, it will not dissolve or come apart. Moreover, Ivory carvers use it and produce very beautiful pieces.”
Fish glue usually is soluble, to render it insoluble it will need to be in contact with metal ions that also applies to hide glue.
Fish glue is a transparent, colourless, water soluble glue. There are various types of fish glues. The higher quality Isinglass to the lower quality, made from the skins of non oily types of fish as well as their bones and cartilage which are sold in liquid format. The agglutinating agents are removed by extraction with hot water, then cooled and dried to produce gelatin or glue. Varied production techniques can produce poor quality fish glues.
The highest quality fish glue is Isinglass which is made from the swim air bladders of Sturgeons. Isinglass was originally made from air bladders of the great Russian Beluga Sturgeon, found in the fresh waters of the Caspian and Black seas. The Beluga is a monstrous sized fish than can live up to 113 years.
Unfortunately, due to its overfishing the Beluga has been placed on the endangered species list which has prompted many governments worldwide to place restrictions on its trade.
In 1939, restrictions were placed on Russian exports, it’s unclear to me whether these export restrictions were solely placed on the export of this fish or on all Russian exports. However due to this, other fish air bladders were used from various fish and Isinglass became a generic term used. North American Isinglass is made from Cod or Hake.
To prepare Isinglass, the air bladders are removed from the fish, cleaned and air dried. The dried bladder is then cut into thin translucent strips, these strips which are nearly 80% collagen are dissolved in hot water then diluted and cooled into flat disks. Collagen is a protein found in cartilages, tendons, bones etc. This is a very strong and soluble adhesive that can be used in low concentrations. Sturgeon glue is rarely available outside of Russia.
Genuine Isinglass fish glue costs around 578 euros/kg or 57.80 per 100 grams (3.5 ounces) Here is the link to where you can purchase genuine Isinglass fish glue https://www.dictum.com/en/surfaces/glue-accessories/natural-glues/450142/isinglass-glue-granulate
Another link but more expensive:
http://shop.kremerpigments.com/en/mediums-binders-und-glues/water-soluble-binders/natural-glues-und-agglutinants/5721/parchment-glue
The purity of Isinglass can vary due to the diverse manufacturing processes, unfortunately there is no way to verify any of the processes. Germany is usually a good source for trusted companies, Milligan and Higgins in the US is definitely a trusted company for hide glue, but I don’t know if they have Isinglass as they have not yet responded to my email. Behlen, I also don’t know what type of hide glue they sell as there is a variety of low to high grade which I will go into detail later. I haven’t also located any of their products that indicate that they sell Isinglass. Lee Valley sells liquid fish glue which is of a lower grade and the one I have, I have tested it despite it being over 5 years old and has worked remarkably well. I have tried with full force to break the pieces apart and cannot do so and remember this is with a lower grade fish glue.
Fish glue is often sensitive to changes in humidity and temperature and can shrink while drying. It doesn’t gel which means you have a long open time; some reports claim 30 mins while others claim 1.5 -2 hrs. It also means you can work in cooler conditions without the need to warm the work prior to gluing. You also apply the glue in its cold state so there’s no heating involved like hot hide glue or liquid hide glue.
Fish glue cleans up with water well whilst still wet, but difficult to clean once its dry. You can also refrigerate it and it will last for many years, the cold prevents the bacteria from forming but also increases the viscosity, so prior to use let it sit at room temperature for about an hour for it to return to its normal viscosity. If frozen you will render the glue useless, once in every few months shake the bottle to prolong its life.
Bloom strength means gel strength and is measured in grams or another term is bloom grams, they could have easily picked one word. Manufacturers commonly distinguish between grades of glue by their bloom strength, which usually covers a wide range starting as low as 30g for weak bone glue, to rigorously extracted hide glues up to 500g being a very strong glue.
Gelatins extracted from cold water fish do not have specified gel strengths as they are liquid at room temperature.
The setting time of animal glues depends primarily on gelling temperature which is known as T gel and gel strength. The lower the T gel and gel strength, the longer the open time of the solution, another words the longer it takes for the glue to gel. High Bloom hot hide glues tend to gel rapidly as gelation occurs at comparatively high temperatures. Gelatinous glues derived from fish have a low T gel due to their chemical structure, and cold set liquid hide glues, are convenient to use when long open times are required. Commercial fish glues usually contain preservatives and, sometimes, small amounts of other additives such as colour brightener, deodorising agents or fragrance. Liquid
hide glues generally have further additives to inhibit gelation at room temperature. These are typically salts, like urea, thiourea or phenols that extend the setting time by inhibiting renaturation of the gelatinous matrix. Some manufacturers claim that their liquid hide glues does not contain gelling inhibitors in which case the gelatinous matrix must be considerably affected by molecular cleavage, and it’s not the hollow between a woman’s breast. Molecular cleavage means molecular separation to achieve the comparatively low molecular weight that is necessary for the glue to be in a liquid state.
In general, glues of higher bloom strength develop tack faster than lower bloom glues.
The tack strength of glues can be tested between the two finger tips.
Isinglass solutions may appear to be less tacky than equivalent concentrations of hide glue, as they take longer to set at room temperature since their lower gelation temperature delays the development of tack.
Drying times depends upon the ambient temperature and relative humidity. Glues dry by evaporation of water however; the drying times can be increased raising the room temperature. It is recommended that these adhesives be allowed to dry as slowly as possible to maximise the elasticity and strength or should I say toughness of the glue film.
Isinglass naturally develops highly stable and elastic films if dried at room temperature, being slightly above its temperature gel. It’s interesting to note if I may back track a little, that heating these glues at high temperatures say 80c or 90c would result in only small amount of loss of strength if only done for a few minutes, anymore would render the glue useless.
Viscosity meaning thickness is an important factor in the choice of adhesive for bonding or consolidation, as it will affect the degree of penetration into a substrate. If the viscosity is too low the glue may penetrate too far into the wood, leaving the joint starved of adhesive. For consolidation of porous materials, high viscosity may prevent adequate penetration and cause stress to develop at the interface between consolidated and unconsolidated areas.
Isinglass has a much higher viscosity than hide glue, in order to obtain glue solutions of low viscosity it is not always advisable to over dilute high bloom glues excessively, hide glue is a high bloom glue. If you did so, you would weaken its strength, leeching, swelling and staining the wood may result if it is water sensitive. In this case, a lower gel strength glue would be preferable. Slow gelation and lower viscosity promote uniform film formation as glue is able to spread evenly, providing adequate wetting of the surface, then again using a larger natural bristle brush will achieve the same result.
Hide glues generally have greater cohesive strength than bone glues which display a lower tensile strength and are much more brittle.
The tensile strength of hide glues is typically around 39 megapascals (MPa) (5700 psi) A tensile strength is the maximum strength that can be applied to it before it breaks, that’s pretty darn strong in my books. Cold water fish gelatins show a comparatively low tensile strength of around 22MPa (3200 psi) which again is very bloody strong. A high tensile strength similar to that of hide glue has been reported for mildly prepared Isinglass from Sturgeon, making it a useful adhesive for bonding wooden joints. Literature confirms that Isinglass has often been used for structural woodwork in the far east, to me that’s impressive.
Although Rabbit skin glue has a high gel strength, it has been stated as having a lower cohesion and bonding strength than other hide glues. This is thought to be due to its high fat content. So stay away from McDonalds.
Isinglass has more elasticity than hide glue. Glue recipes often contain additives such as sugar alcohols (glycerine, sorbitol) and polysaccharides (dextrins) to improve elasticity and toughness. One traditional method for achieving elastic and resilient glue films is in the addition of honey. Sugars are hygroscopic, by adding water you induce gel strength and viscosity. These additives are known as plasticisers even though they don’t actually plasticise the glue. High proportion of fat also improves the elasticity but at the cost of reducing final bond and gel strength. A high water content or an excess of hygroscopic additives like sugar, can promote an unwanted tendency to creep.
Animal glues are well known for their resolubility or better known as reversibility, but it can be rendered insoluble if it comes in contact with metal ions e.g. Metal foils, tools, pigments), or with certain organic pigments and tannins, either before, during or even after their application. A pigment is a colourant but so is a dye, the difference between the two is that a pigment is insoluble, while a dye isn’t because it’s a liquid. Cold liquid hide and fish glues, the ingredients of which are unknown to the supplier and end user, may already contain additives that promote cross linking and, therefore, increase insolubility. I have read many reports of users claiming they had extreme difficulties pulling instruments apart for repairs. This is why I cannot stress this point enough, to always buy from a trusted source like Milligan and Higgins. I’ve never used hide glue from anyone else and therefore I cannot vouch for them but I would never buy the cheap ones offered on eBay as you just don’t know who manufactured them. There has been a lot of rave about Behlen hide glue, I don’t know because I’ve never bothered to investigate. It’s a German company and Germany is well known for quality products.
Liquid Hide OBG – Heat in bottle up to 140°F (60°c)
Hot Hide Glue – Measure weight by volume of water, take how much you’re going to need and place it in a plastic or glass container NOT METAL then fill with cold water just to cover the granules and leave uncovered for half hour or best 24 hours. Heat gluepot to 140°F and cook your glue. Stir occasionally, to thin it add hot water equalling the temperature of the glue. Do not over thin it and don’t let it be too thick, if it’s thick it will gel quicker resulting in a poor bond. Clamping time minimum 12hrs best 24hrs Reactivate with heat and water.
Liquid Fish Glue – Use in a cold state (no heating required) Clamp for minimum 12 hours, best 24hrs. Cleans up with water best when glue is still wet. Reactivate with water
Isinglass (Highest Quality Fish Glue)
This is an extract from Alba Art Conservation
STEP BY STEP: HOW TO MAKE GLUE FROM FISH BLADDERS
Part of the routine activities of conservators is to make our own tools and solutions for use in conservation treatment. Many traditional materials can be found on specialty websites and in stores, but some we just prefer to mix ourselves. Isinglass is a natural and refined glue made from gelatin from cooked down sturgeon bladders. It’s optical properties, such as reversibility, aging characteristics, and strength, make it a very good choice of glue to be used in many conservation treatment applications. It is used mainly in consolidation (stabilization of flaking media), though also has applications in tear repair, facing, and as a general adhesive. I hope this blog post illustrates the care and time conservators put into selecting (and making) their materials, as well as the actual treatment of art.
First, the swim bladders of the sturgeon are purchased dried and unprocessed. They should be free of blood clots and other large inclusions. For this project, I used 50 grams of dried Salianski bladders purchased from L. Cornelissen & Son.
The swim bladders should be soaked overnight in water using approximately a 1:10 glue-to-water ratio. I eye-balled the ratio in a large glass beaker to a final volume of about 800 ml. To help them absorb water, the bladders can be cut into smaller pieces. I found this time-consuming and difficult, so I ended up soaking them whole. After a period of 24 hours, the bladders should be spongy to the touch and able to be easily pulled apart.
Once the bladders are sufficiently spongy, they should be kneaded into a homogeneous blob. The texture was kind of doughy at this point, and obtaining the blob was easier than I thought. Any hard bits should be worked into the dough. If there are a few remaining, they will be filtered out at a later stage. 
The glue and water were placed in a makeshift double boiler using the glass beaker, a wooden block, and a large cooking pot. The mixture should be cooked in hot water, never exceeding 140 degrees F (60 degrees C). I allowed the glass beaker to come to temperature in the water and kept a digital thermometer in the cooking water to monitor the water temperature. To double check, I also kept a meat thermometer inserted in the water and had a glass of cold water on hand to cool the water, if necessary. As the water began to reach temperature, the mixture became cloudy as the dough began to dissolve. The solution was stirred with regularity and after about 45 minutes, the glue was mostly in solution. I found that I had to get the outside water temperature very close to 140 for the majority of the mixture to dissolve. The water eventually became more clear as the dough melted. To see that all was well, I checked the tack of the glue as it neared completion, and the results were satisfactory.
After cooking, the solution was filtered into a large glass jar through a nylon stocking. The material remaining in the stocking should be squeezed through to help dissolve any remaining bits. This solution was then re-filtered using the same stocking. Bits remaining after the second filtration can be discarded with the stocking. At this point, the solution should be yellowish and clear of bits. I poured it onto a sheet of non-stick Mylar that had been previously prepared over a large table. Incidentally, I also had to prepare an additional sheet of Mylar to accommodate the large amount of glue produced. The glue should be left undisturbed to dry. To make more homogeneous and complete sheets, I attempted to spread the glue mid-drying with a piece of stiff Mylar with some success. I did end up getting areas of pooling that took longer to dry than others.
Once the sheet is sufficiently dried, they can be easily separated from the Mylar and cut up into smaller pieces to be stored for later use.
The cut up pieces can be stored in jars and re-dissolved in water as they are needed. Though lengthy, the preparation of the glue yielded enough dried glue to last for a few years. The product is very refined and sure to contain no additional additives, bulking agents, or colorants.
For the instruction on the preparation of isinglass, I would like to give credit to my graduate painting conservation professor James Hamm at Buffalo State College and to Jill Whitten and Rob Proctor.
I have included a table you can download. It a comparative overview of each glue
I think I have covered many useful topics and you should now have a solid understanding of the various types of animal protein glue without the unnecessary glossy scientific details which I have omitted, as it does not benefit us the woodworker in knowing it. As for the contradictory data for Isinglass from sturgeon, one test from Pryzybylo indicated that the glue was resoluble in water after both tests of natural and artificial ageing was conducted. However, another report from Michel et al. indicated that their artificially aged sturgeon isinglass was insoluble in water. As you can see these are contradictory results which may be due to different preparation procedures, light source, exposure time, temperature etc. In reference to the Caspian Sea fisherman on his eye witness accounts of where the object was soaked in water for up to ten days and did not come apart is in line with Michel’s findings, but just what preparation did the ancients use to render this glue insoluble is unknown.
Animal protein glues has many uses in all fields of many trades but there is no one particular glue that you can generalise as a general glue type. Each glue has its pros and cons and each glue will perform different tasks. As an example, you cannot use hide glue for bonding metal to wood but instead you would use Fish glue, but the same glue wouldn’t suffice for gilding, instead you would use rabbit skin glue. So, as you can see they all work differently to each other, so it’s up to you as a craftsman to understand what your glue can or cannot do, and to use the appropriate glue for the job on hand.
I think by now with how much I have written on this subject not only in this article but in all my previous ones that animal protein glues, is my go to glue.
If you are experiencing problems with your glue losing its bond as I have read on many forums from Luthiers, you need to ask yourself what quality of glue are you using. Is it from a reputable source? Very high humidity can also be the cause due to high levels of moisture in the air, dry heat is not the cause. As you know by now that Fish glue is high in viscosity, by thinning the glue you’re basically starving the joint. What little glue is on there holding your piece together will come apart in even slight humid conditions. Another factor at play is people using hair dryers to force the drying times, fish glue works best when its left to dry slowly and naturally. If your workshop is in a damp environment then don’t expect much results with any animal protein glue, if your wife’s dryer is in your workshop, your shop including all your tools and wood will be soaked. Look at your environment before you blame the glue doing what it’s supposed to do.
Your customers also need to be made aware of potential mishaps and how to avoid them. All in all, in all my years of using hide glue and this fish glue is the first for me, nothing has come apart, and conditions in my area in summer are extreme, soggy high humidity. I have also just used fish glue instead of epoxy to fill in a crack in a knot on my recently bought bowsaw, it worked wonderfully and as you know this fish glue is very old and I’m confident it hasn’t gone off. Equally it’s the lower grade one from Lee Valley not the high grade Isinglass. It’s also been several days probably a week since I glued to sample together, still its impossible to break it apart. I will give it a test in the laundry when my wife uses the dryer next, just to see if it will come apart and that will the most extreme conditions.
If you’ve read this far then congratulations are in order, this length of post isn’t the norm for blogs but I do hope I will make a regular habit of it.
Take care
I feel like I’ve only just scratched the surface on this topic which prompted me to add further notes, however I am aware that most people would rather view than read but unfortunately I do not have a professional studio setup with cameramen to aid me so we’ll just have to do it the old fashioned way and read.
Protein glues are made by cooking protein for lengthy time, you could put a soup bone in your soup and cook it for too long and your soup will turn into glue. You have fish glue, rabbit skin glue, bone and hide glue. Fish glue is the only one that is liquid in room temperature but is not as strong as a mixture of bone and hide glue but OBG is not made out of fish glue. Rabbit skin glue is used by guilders to apply gold leaf to their furniture, this type of glue must be diluted quite a bit. Bone and hide is mixed 2/3 to 1/3 to make good furniture glue and are measured in gram strength, this measurement is taken by pushing a tool into the dried glue. The gram’s strength varies from 100 – 500, 135 gram strength is used to make chip glass, 192 is a good compromise and most commonly used for furniture in terms of medium setting. The higher the strength the faster it sets and the more brittle it is.
The beauty of animal protein glue is that it can be used over and over again, be it 1000 or 5000 years old you just reheat it and use it again, I don’t know of any modern day product that can be used multiple times and in a single year let alone 1000 years from now.
In the old days they sold the glue in cakes and would also have the makers stamp on it, to cure it they would put it on a wire mesh so as not to let it get mouldy so they would let it dry hard on a screen so they could later sell it.
Marquetry and veneering cannot be performed with modern day glues, yes they can be glued with modern day glues but they rarely last for very long and so hide glue is the only glue that is used in veneering and marquetry.
I have only ever used liquid hide OBG and Titebond after experiencing the two my preference goes to OBG, on the other hand I have never cooked my own glue. This is an area I would love to explore as OBG is getting far too expensive living so far away from the source. I offered to you a recipe from Don Williams on making your own liquid hide glue with no spoil date. I have written to Patrick Edwards about this but he hasn’t responded.
It may seem medieval to some to resort to what may seem like primitive methods of gluing two sticks together and even some what cumbersome to make when readily available modern day glue off the shelf works perfectly fine. All be it I believe it is the perfect choice for gluing timber and without repeating all the benefits of using animal protein glue please refer to the first article but in terms of cumbersome or time consummation of making the glue I believe the time difference between making it or using PVA or yellow glue actually consumes the same amount of time. HA???? How you may wonder. To clean up modern day glue properly takes more time than it does to make Hide glue. I did say they are on par here but after thinking about it I figured it actually takes longer to clean up the mess. With hide glue you can wash it off which only takes minutes but with PVA or yellow glue washing it off after it has dried is not possible and you can’t get a chisel in those tight spaces without risking digging into your furniture piece. So in hind sight it makes perfectly good sense to incorporate hide glue in your everyday woodworking.
I believe this now concludes what I know about animal protein glues, I’m sure there is more information out there on the net if your still eager to know more about it. All I need to do now is figure out where I can purchase 25kg bags of the stuff.
Animal Glue also known as hide glue or protein glue has been around since the Neanderthals, no they weren’t making furniture but instead they used it to protect their painting from moisture. There is also written evidence found around 2000 BC the Egyptians were using hide glue. This glue was found on their caskets and furniture in the Pharaohs tombs. The Greeks and Romans also used animal and fish glue for their Marquetry and veneering, Chinese and even American Indians were found to use hide glue.
Animal Hide Glue is made from, well, animals, skin, tissues, bones (hoof, teeth etc.) what type of animal well mostly horses that were going to be put down. Other animals include rabbit, fish and Ox
Hide glue comes in a granular form, flakes and flat sheets which do have an indefinite shelf life if kept dry.
To use it you must first dissolve it in water, then heat it in a glue pot be it over fire or an electric stove to about 140F (60c) but no more than 180F and you cannot boil it as high temperature will destroy the glue strength. You must work quickly which is a disadvantage as the temperature drops the glue starts to set. The open time will vary on the gram strength which range from 120-250, the latter having the shortest open time and I believe it to be around a minute. I have a PVA glue that has an open time around 2 mins which comes in very handy when you need to glue some small parts and you cannot clamp it, it takes 4 hours to cure which is pretty bloody awesome. Hide glue takes anywhere from 12-24 hours to cure which is pretty much standard for most glues on the market.
As I said above hide glue starts to set as it cools down and begins to cure as the water evaporates from it, hide glue will not cure if it is soaked. Why would you soak it? Beats me.
Patrick Edwards who is a scientist by profession but now known for the last 30 or 40 as a respected antique furniture restorer who does many jobs for the Smithsonian developed the OBG (Old Brown Glue) which is hide glue with a gram strength now honestly I can’t remember whether it’s 192 or 250 that can be used at room temperature and has an open time of 30 mins. This was made possible by adding urea, now Urea isn’t a new invention, woodworkers discovered back in the 19th century if you add Urea to the mix it would extend the open time and keep it in a liquid state but back to OBG. OBG has a shelf life of 18 months from its creation date so you’d hope it hasn’t been sitting on the store shelves for too long. It can be frozen to prolong its shelf life and it does not affect its qualities. 18 months is pretty darn good as no other glue including Titebond’s Liquid Hide Glue can make that claim. All glues except for OBG has a shelf life of up to 12months.
OBG gluing strength is equivalent to hot hide glue. Knowing that OBG is equivalent to hot hide and I use the term hot in reference to using a glue pot eliminates the need of having to use a glue pot but for the sake of tradition and expense using a glue pot is a better option if you are going to be making a lot of furniture, clocks whatever everyday as it is pricey in this country to buy OBG. Of course it’s a lot cheaper in the US, everything seems to be cheaper in the US not sure why the yanks are so tight with their money, try living in Australia then you’ll see what expensive really is. Anyway shooting my mouth off again, the process is the same you still need to heat it up but not in a glue pot but using hot tap water instead. If your boiler doesn’t heat your water to 140F up to and no more than 180F which mine doesn’t I boil the water in a kettle and mix some cold water and pour it in a jar which I’ll monitor the temperature using a thermometer used for cooking and then place the bottle inside the jar. I purchased a small empty bottle which I use and store the large bottle in my freezes and top it up as I need to.
Hide glue is not a gap filler so if you suck at making good tight joints I wouldn’t recommend using it, the reasons are because of the drying process. As I said above hide glue cures by losing its moisture if the joint has gaps then the moisture in the glue doesn’t evaporate and won’t fully cure it will remain gummy due to the moisture in the air. However, if the joints are tight then the wood absorbs the moisture and the glue dries hard.
When it dries it dark but clear and yes it will darken more over time but obviously you won’t see that, if you’re a messy woodworker no problem you can leave it on which you wouldn’t but you can as it does not affect any finishes unlike every other glue on the market that will, or you simply scrape it off or yes wash it off. Just by applying a damp cloth it will come straight off again no other glue including titebond liquid hide can make that claim. In fact, titebond say’s in their fact sheet if you apply a few drops of water it will weaken the bond, also titebond say’s in their safety sheet not to get glue on your skin as it will cause irritation and so forth. Not so with true hide glue, with hide glue you can cover your hands in it. It will be very sticky and uncomfortable but it simply washes off with water, no soap nor turps or industrial soap required, just plain old water will do it.
Lastly you reverse protein glue by adding moisture and heat to it.
Hide glue is also known to set on itself by performing a rubbed joint, so when edge gluing you apply glue on both edges. You rub the edges against each other until it tacks and then set it and leave it to dry without clamps. As it starts to dry the glue will pull into itself forming a tight gap free joint. Hard to believe but it’s been done like that since the 16th century when furniture making begun as a craft.
You may be wondering just how strong is it, well I can tell you I build all my clocks, furniture and now I’m starting boxes and none of them have come back. I’ve even glued as test piece a mitered corner joint, I’m still yet to break it apart. Maybe I’m a weakling but I tried to break the joint and couldn’t do so and remember that’s end grain gluing. The trick to this is simple, you apply glue to both mating pieces then allow the end grain to soak up what it can and let the rest dry a little to form a thin film. Then you apply some more glue and mate the pieces immediately together without any waiting. Clamp it and walk away and the next day it should not come apart.
To tell how you know hide glue in particular the liquid hide and not titebond but OBG has deteriorated. There are some signs to look for, if you know the expiry date is up it doesn’t mean that it’s useless as OBG hide glue has been known to last 2 years but everything has an end so here are the signs.
The proteins break down and the glue becomes very runny at normal room temperature, there is a foul odorous smell and mould begins to form. If any of these things occur its time to chuck out your bottle and buy a new one. There’s no point in keeping it even if it’s ¾ full, like Chris Schwarz said without glue you’ve got nothing but a pile of wood sticks or something along those lines.
If you don’t want to purchase OBG you can make it yourself. But you would need a glue pot, hide glue and salt. To save me writing anymore than I need to here is an extract from Don Williams, senior furniture conservator at the Smithsonian’s Museum Conservation Institute.
To make a batch of liquid hide glue takes about three minutes of active work, according to Williams, but it’s three minutes spread over a 48-hour period. And you don’t need anything special in addition to the hide glue – except table salt.
To begin, you have to make hot hide glue. I’m sure if you have yet to purchase a glue pot (a special pot for making and reheating hot hide glue), you’re not of the mind to do so for this single purpose. You don’t have to. You can use an electric hot plate, a saucepan, a small glass jar and a small amount of hide glue flakes or pearls, along with salt.
Here are the steps: The first day, mix two parts hide glue flakes with three parts water into the jar and let everything soak. The following morning, heat water in the saucepan to a temperature of 140º F (a thermometer helps with accuracy), add in one-part salt to the jar then cook everything for about two hours. Next, immediately stick the cooked mixture into your refrigerator for the balance of the day (quick cooling is key).
On morning three, fire up the burner and cook the mixture for another two hours (Williams always cooks the glue twice). Once the batch cooks the second time, you have liquid hide glue. Williams adds that he seldom makes more than a pint of glue at a time. He pours it into a plastic ketchup or mustard squeeze bottle for easy dispensing.
And here is the most interesting part of home-made liquid hide glue: The salt makes this product stay liquid at room temperature and salt preserves the glue so there is no spoil date – just as salt has done throughout time in salting meat.
Hide glue has been used for thousands of years and yes it has stood the test of time the tombs are filled with furniture and caskets still held together with hide glue. It wasn’t until WWII when they decided they needed to make glue that didn’t involve a lengthy setup process and hence PVA was invented. Yes modern day glues are very strong in fact so strong that you will break the wood and not the glue joint but they are not reversible. What does that mean to you though, probably nothing. If you want someone in 150 or more years to repair your now antique then hell yes it means something. It means something to someone and it should mean something to you as a craftsman. I as a craftsman who works solely with hand tools care enough to what I put on the things I make from the finishes down to the glue. On the other hand I’m a traditionalist, I tend to follow what they did 300 years ago. Why because it works, it wasn’t broken then but we broke it today due to the unnecessary war we had and the wars we still have, due to mass production, higher profits, bigger demands it must get done yesterday. Hide glue has proven itself but you and I will not see if PVA will prove itself, Maybe it will or won’t only time will tell but I am sure glad that there are companies out there who still produce hide glue and I’m glad that there are thousands of craftsman probably millions around the world who have created a demand for such products to be made available.
That’s all folks hope you learned something new or refreshed old memories. No matter what you use, use it well and enjoy your craft.
Till next time
Journeyman's Journal