It's been many months since I wrote about my recurve bow Hesykhia and to be honest, she's been a little neglected with everything that's been going on. I also ran into a quandary about exactly how I would restore her.
RESEARCHING GLUE ... a LOT
After weeks of researching about recurves and bows in general, I learned that there are only a few glues that are recommended for bowyers to use. Note: I'm not a bowyer so I had no idea about this and the industry standard glues are made in USA. They are very expensive! I had to find out what the glues were so that I could find an alternative that was not as expensive but would do the job (hopefully).
Getting the necessary supplies together and everything disassembled before starting
For lamination, Smooth on EA-40 clear epoxy resin is the best bet, followed by Titebond 3. Urac is also used by many (liquid urea formaldehyde glue). Hide glue is also mentioned as a great option and is a protein colloid glue made from the boiled down connective tissues of animals. I know, it sounds rather gross.
EA-40 is an unfilled low-viscosity epoxy adhesive that dries clear. It takes 24 hours to cure at room temperature and provides a water resistant bond. The safety spec sheet recommends heat curing, but I don't have a heat curing oven that I'm prepared to have fumes in - I'm certainly not doing it in the kitchen!
The crack in the lamination of the riser
I tried to find out what Titebond 2 and 3 are but it seems like a rather well kept secret. The only thing that I could find was that type 3 is a Advanced Proprietary Polymer and type 2 is a crosslink polyvinyl acetate (a type of PVA ie: carpenters glue). So then I decided to go and look up the different types of glues so that I could maybe find an alternative.
Polyvinyl acetate (PVA) is a rubbery synthetic polymer that creates a flexible, permanent bond. This is essentially normal wood glue which is ideal for a wide range of wood and craft projects, especially for nonstructural wood-to-wood bonds. White varieties of PVA are designed for indoor use, while yellow varieties (called carpenter’s glue) are made for outdoor use.
Now I felt like I was headed in some form of a good direction.
Administering glue into the crack from one side to the other before cleanup
The riser after careful and even clamping after cleanup. You can see that the crack has now been closed up
I then looked up what properties polyurethane glue has.
Polyurethane is a synthetic plastic resin that creates tight, lasting bonds. Used for everything from paint to wood floor finishes, polyurethane is a primary ingredient in many wood glues. These wood glues excel when splicing boards together like connecting two lengths of crown molding. It forms flexible, durable joints.
Polyurethane is moisture activated, meaning it relies on the moisture in the air to set, so it bonds very well in humid conditions, unlike other wood glues. It also doesn’t dry out sensitive wood fibers. source
Applying glue to the inside of the delaminated bow limb before clamping
The bow limb clamped up and bound after cleaning up the squeezed out glue
I then spoke to the person who's compound bow I used a few weeks back and he is a flight engineer with a pretty extensive amount of knowledge on a wide range of topics. He recommended trying a polyurethane glue as he thought that normal PVAs would simply not be strong enough for a 40pound recurve's draw strength. I then went and spoke to a salesman at one of the large hardware stores and asked him for his opinion. He also thought that Polyurethane would provide strength but also flexibility. He was very dubious about using a PVA glue.
So after various discussions and a lot of reading, I went with polyurethane. Whether it was the correct choice, I don't yet know.
I didn't use very much at all and applied it slowly into the crack in the riser from one end to the other so that it could sink into the crack completely. I wore protective rubber gloves (which made taking photos a challenge lol) and had a cotton rag at hand to clean up the overspills and squeeze-outs as I went.
The polyurethane glue used
The glue has quite a long set-to-tacky time so I worked methodically and didn't rush anything. Once I was happy that the entire crack had been filled, I brought out the clamps and applied even pressure with them along the riser, cleaning up the excess that squeezed out as I went.
Once I had completed that, I moved on to the split limb. I had to open up the split sufficiently to evenly spread the glue (I used a small wooden dowel for that) and then I used 4 clamps across the limb. I then realised that I didn't have sufficient pressure to seal the joins the way I wanted them sealed, so I used the old bow string to carefully pull the lower lamination of the bow limb into the original curve and provide a good seal.
Both riser and bow limb clamped up to cure for two days
I left the parts to cure for two days before I unclamped them. The joins look great and you can hardly see that there was a crack in the riser, it looks like the original lamination.
As for what happened next, well I had to laugh at myself to be honest.
This is a 40pound draw weight bow and is 58" in length. I'm not very tall and not very well muscled either.
Trying to string this bow is going to require a stringer because there is simply no way that I can do that mad cowboy style stringing thing with my leg and I was way too scared that the thing might go horribly wrong and wound me in the process.
So now that I've glued her up, I'll need to either take her to an archery range and see if she can be strung with a new bow string or if my glue seams will fail and the limbs snap. It's going to be an interesting experiment either way.
Would you have done anything differently? Please let me know in the comments what your thoughts are.