Wayne Nelson, MA, Dip. IM.AR.AD.ASG

If, like me, you did woodwork and metalwork at high school, you may remember using animal hide glue for your woodworking projects. This wonderful glue used to come in powdered or pellet form, and all that was required was to mix it with boiling water to the desired consistency and let it set. Later, in the workshop, the old cast iron ‘double boiler’ pots would be brought out. If the glue had been made up in a jar, the jar could be put in the larger of the two pots, in which there would already be hot water to soften the glue, or, if the glue had been made up in the small iron pot, the pot would be simply placed inside the large pot with the hot water and heated until the glue softened to the consistency of paint. The aroma of this glue is said to offend housewives if the glue is being made up on the kitchen stove, but to me it always seemed to have a characteristic sweet smell that promised interesting jobs and things to be made.

For years, however, I have used white PVA glue for my woodworking because that is all that seemed to be available. PVA glue is less than satisfactory, for all its availability, because it leaves a stain or pale discoloration in wood surrounding ajoint, and nothing will remove that stain. It is particularly annoying since if the surrounding wood is to be stained a different colour or varnished or polished, the discoloration just keeps on keeping on as they say. Needless to say I have tried to avoid using PVA for repairing broken gun stocks, trying other such glues as Araldite. The problem with the latter, and other proprietary glues, is that for restoration work where the arm is not likely to be used out in the field, the modern glues just don’t seem right. They also seem unethical if you want a repair that is capable of being reversed. Reversal is quite important in restoration work, since it may prove necessary to take an arm apart again for interpretation. Animal hide glue, therefore, provides a satisfactory solution since it has excellent sticking properties and will last for a hundred years or more in a stable environment where there is no hot sunlight or rainwater. The Advantage, from the restorer’s point of view is that this type of glue can be easily taken apart through the application of either heat or water, the very elements that would otherwise attack it if the arm were to be used again.

Recently a friend of mine, who is an expert furniture maker in his own right and managing his own business, lent me a video tape on furniture restoration produced in the United States last year by a man called Bob Flexner. Bob Flexner repairs all kinds of wooden furniture, both old and new, but his speciality is restoring antique American furniture which, over there, means furniture going back to the eighteen century. In his hour long fascinating video, Bob Flexner describes a number of problems faced by the furniture restorer and the kind of solutions which are appropriate to this discipline. There is plenty of information, and from a gunsmith’s point of view I would say that most of it is relevant if you think laterally. Inlays, for example, and how to make them and replace missing ones, is a subject Flexner discusses which has relevance for gunsmiths. How to repair large breaks and hairline cracks in furniture is another.

Bob Flexner explains the strengths and weaknesses of all of the conventional proprietary glues available to the woodworker in the United States, and all of them are familiar to us in New Zealand except, as I shall explain, animal hide glue. Animal hide glue, according to Flexner, is the only glue to use if you are restoring something valuable. And he explains why in no uncertain terms. Firstly, it is good glue because it sticks – and really sticks. Secondly, it is ethical because this was the only glue used by woodworkers (and possibly gunmakers, along with fish glue) until at least the end of the Second World War. Thirdly, animal hide glue is reversible.

To demonstrate all these qualities, Flexner, using a paint brush, slaps some animal hide glue on a mortise and tenon joint and explains that no clamps are necessary because of the sticking quality of this type of glue. This does in fact make the job easier for the craftsman. To prove the point he picks up the item just glued and waves it happily in the air. One expects to see the whole thing fall apart, but it doesn’t. Next, Flexner picks up a hypodermic syringe, fills it with a little of the hot animal glue and then, with the care and precision of a surgeon, neatly fills a hairline crack. Just the thing that is needed for filling those hairline cracks behind barrel gangs, or between the barrel tang and the sidelocks of a shotgun, or along the fore-end somewhere. Flexner then goes on to demonstrate the use of animal hide glue for fixing inlays, making the point that if the joint or inlay was historically fixed with this type of glue, it is sometimes necessary only to steam heat the inlay to reactivate a glue that is a hundred years old. Flexner even suggests that with an antique it is reasonable to advocate breaking the old glue apart every hundred years or so – which is easy to do since the glue does become brittle over a very long period of time – and reglue it. The beauty of it is that with animal glue there is no need to scrape the old glue off the surface of the wood; all one needs to do is add fresh glue to the glue already there. But if it is necessary to do so, animal glue can be simply removed with water or alcohol. Hence the excellent reversibility of this type of glue. From a restorer’s point of view this is of key importance since no restorations hould irretrievably damage an item such as PVA would. However, a word of caution is necessary. As I have suggested above, animal hide glue is not suitable for arms repair if the arm is to be used in the field where sun and water are likely to soften and dissolve the repair. It is suitable, however, if the repaired arm is to be displayed or stored inside in a stable environment such as one would keep valuable furniture in.

After seeing all this I was reminded of the fact that I had used animal hide glue at schook, and that, until recently, I still had a table that I had made thirty-seven years ago that had been glued in this fasion, and that it was still a good table. Animal hide glue, I decided, would do very well for gunsmithing repairs concerned with conservation and restoration. All I had to do was go down to the hardware shop and buy the powder and a double boiler.

Well, finding a double boiler was an odyssey in itself. I didn’t buy one because the only ones available were to be found in antique shops – and in the shops I went into, suffice to say they saw me coming. As far as the glue itself was concerned I was astonished to learn that animal hide glue is not commonly available in New Zealand today, except in very large bulk form. I made enquiries of about eight different firms in Wellington, Auckland and Christchurch, including the big glue manufacturing companies National Chemicals, Bostik, and Leiner Davis. The lack of knowledge about animal hide glue and its properties was appalling. An ‘expert’ at Bostik told me categorically that Urea Formaldehyde was the same thing as animal hide glue! It seems that Davis Gelatin, Christchurch, did make animal glue in powdered form sold in convenient packs for the small craftsman. But they have apparently sold that part of their operation to National Chemicals in Auckland. The National Chemicals expert told me that they now manufacture animal glue for export only, mainly to America, but I wanted some, the minimum quantity he could sell me was a pail containing 20 yards of the glue in pellet form. It seems the equipment required for making animal glue is specialised and expensive. No one else in Newl Zealand now has the equipment (according to this source) and the only way making the glue can pay is through large export orders – not for a small workshop unless the size of your business is such that you can justify buying large quantities. Maybe Bob Flexner is using export New Zealand glue.

Finally, I made contact with a fellow soul at Leiner Davis, Christchurch, who has a genuine sympathy for woodworking restorers, an understanding of animal glue, and having a deep regret at the disappearance of the handy packets of animal glue powder that were once available. It was he who informed me of the simple fact that David Gelatin in powdered form is made from the same animal extracts that hide glue is. He gave me the following recipe for making your own animal glue, and I pass it on here for the benefit of members of the Society of Gunsmiths who may wish to try it:

1. Buy a 250 gram packet of Davis Gelatin at the nearest supermarket, and a packet of Sodium Benzoate (cooking additive, also used for preserving)
2. Bring a saucepan of water to the boil and add the gelatin, whisking it in briskly. The ratio should be 50/50 or one full packet of gelatin to an equivalent volume of water.
3. Turn the water off the boil to about 60°C. Keep stirring the mixture for the next ¾ of an hour. The important thing is that all the gelatin be dissolved completely. The consistency of the glue should be about that of paint or slightly thinner, and the colour will change from the white of the gelatin powder to the dark brown which we know as the colour of the old animal hide glue.
4. Allow to cool a little and bottle the glue or use it immediately. If the glue is to be stored and used again, add just a pinch of Sodium Benzoate to stop bacteria from eating the glue when it is in storage. An Agee preserving jar is suitable for storage.
5. To reuse the glue, just heat it up in the same manner that one used to with the old animal hide glue, i.e. either use a double boiler pot if you have one, or place the jar in a saucepan of hot water until the glue melts and reaches the desired consistency for application.

I have made up glue according to the above recipe, and find that the result is everything I had hoped it would be.