Author Topic: Sinew re-glue...  (Read 1389 times)

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Offline Hector

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Sinew re-glue...
« on: November 11, 2013, 04:29:07 pm »
Hello,

Due to a fail on applying 2 layers of sinew onto a 40" oak D bend flatbow I had a perfect one piece removal, the entire backing, glue as well. It left the back of the bow without leaving a single mark on flexing just under an inch.

The stave is untouched outer ring for the back but I had overlooked that i'd burnished oil into it several times years previously. THIS time I grooved with a hacksaw blade, washed with leather dye thinner added tight recurve tips and a slight reflex in the handle, giving overall about 3 or 4" reflex. Thought about deflex handle but I'm pretty sure would not gain much as I understand sinew reflexes the bow more efficiently or to a greater extent than just putting it on a flat stave?  its on now hopefully for good this time..

Anyway, after sizing the grooved and (hopefully by then degreased) back with thickly syrup-consistency glue I put the single piece sinew backing onto a black plastic bag whilst the sizing dried, mist spraying regularly with hot water (1/3 cold 2/3 boiling) over about 2 hours, keeping covered with the bag when possible. This trapped the moisture and yielded a ready to use, fully water-soaked and pliable backing (basically similar to horn-bow glue/sinew prep i suppose?), which then was "blotted" of excess water with kitchen towel, and coated along with the bow in very hot same consistency glue and allowed to become tacky.

Basically on it went, one go, like it "wanted to be there" - no tangles (as anticipated) or bits falling off, in fact was more like slightly more malleable rawhide to apply. Had a few lengths of sinew over so decided to wrap in shallow spiral the whole limb (about 1 twist per 2") with single or double strands just for good measure. Have to post again to see how that turns out. I may end up removing them  but only after its fully cured, and will probably end up rasping or sanding them off the belly side..seemed to hold everything together nicely, especially the tips, have always had an issue of nothing wanting to stay glued at the middle of the recurve. Main reason for this is that I dont like using cord or bandage or anything that I have to remove from the backing when its glued. Also I find it tricky to assess what the backing is doing underneath the bandage, although once it went on it was there, felt like moving or attempting to reposition would definately stretch or break it, as was only two layers thick.

24 hours later its stuck fast and almost non-tacky to touch. Its already gained an inch of reflex give or take, I checked the whole bow over and the only problem is (as usual in my case)
the backing migrating slightly to one side, but apart from that its there I think. The crossed bindings have held everything down well, just got to decide when and if to remove them. Just remembered I forgot to gloss the back over first with cloth warm/water, so might turn out to be a creaky one.

Will post agian when things are drying out a bit, hope some of this has been of use.

H