Primitive Archer
Main Discussion Area => Bows => Topic started by: Qwill on November 22, 2009, 03:29:11 pm
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I have a juniper short bow, about 42" long with a mild reflex and recurve. I put sinew on with knox gelatin glue, and the whole thing turned to jelly and pulled off. It was a mess. Has this happened to anyone else? I put the glue on in my basement, and it was fairly cool and dry. after I finished, I took it outside to let it set and keep it out of my wife's way. (all this was done in the laundry room...) Anway, I couldn't help but check on the bow about an hour later, and it was just a mass of jelly. Any help would be greatly appreciated.
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how cold was it where you were applying the sinew ??
If it was too cold it's likely that the glue gelled before it got the chance to adhere properly.
.....sinew is best applied at a comfortable temperature- for you and the glue. ;)
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Hi Quill, Knox ( or other collagen glues) are supposed to jell!!!!! You say it "pulled off" so it obviously didn't adhere to the wood as it should. Hide glue adheres best to a clean, non greasy surface. Actually I think it adheres best to other collagen surfaces. Any dirt or oils from your hands can decrease adhesion. You should degrease the back of your bow. Some people use acetone. I use Grandma's brand lye soap. Scrub lightly and and rinse well. Then after the wood has dried overnight , you should size the wood. Sizing is an application of thin glue ( ie. use less of the Knox per water). Let the glue dry overnight and then when you place your sinew layer you will be gluing to the thin layer of glue that is already adhered to the wood. The sinew bundles are thouroughly wetted in the glue and laid on the bow and then as the glue cools it will jell and hold the sinew in position. Some people wrap the sinewed bow with ace bandages to flatten the sinew and prevent lifting. I don't think that's necessary, but it may help, especially in recurved areas. Working in a warm moist room is an excellent enviroment for applying glue ads the glue takes longer to set. The laundry room was a good choice.
It is probably too late now, but until the glue dries you can reactivate the glue with gentle heat. A blow drier on high or holding over a hot plate, etc. will reliquify the glue and allow you to reposition the sinew.
I know it sounds complicated and adds couple of steps, but if you wanted instant results you could just go to the local archery shop and buy a bow.
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I did degrease the bow with lye soap, and I did size the back before applying the sinew. I did not wrap the bow, but I have heard differing views on the subject. What I need to know is if anyone has had an experience with their hide glue turning to jelly. I know it is gelatine, but it should start to set and then gradually harden, correct? Does cool temperature have that effect? Perhaps I didn't clean the bow of all the lye residue? Did I leave too much glue on the back? I
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Hi, Well yes the glue will always gell, or in other words turn to jelly. Since you did the proper preliminary steps, I'll suggest two other possibilities. One, the sinew itself will shrink from cooling. Perhaps, in moving from the warm laundry room the the outdoors you caused a large enough change to lift the sinew off the bow. The gelled glue is not very strong so it wouldn't take much shrinkage. Two, you may have mixed the glue too strong. Thicker glue means more glue sticks to the sinew and the resulting in a more prominant "jelly" appearance. Ron
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Did you soak your Bundles of Sinew in Warm Water to rehydrate them first...and towel off the excess Moisture before dipping them into the Knox Glue? All Sinew/Hide Glue Jobs will swell after they are applied...then they will take Days to dry and start to Shrink...and they must be kept warm to do so...not Hot...and definitely not Cold either....as for wrapping Sinew...I have had good results doing so....just don't use something that will not Breath....such as Inner Tubes or Saran Wrap....these will hold in Moisture and may promote the Growth of Molds and will further Hamper the Evaporation of the excess Moisture....I have used Ace bandages after the Glue has passed the tacky Stage...also used Jute Twine too.
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From the 3 times ive backed a bow I have always used knox gellatin and it has worked. You might have mixed it to thick, if that wasnt the case then it is probably because you did not use a bandage to wrap it around so it could hold the sinew down. The first thing that happened when I backe the bows was the gellatin turned into jelly for about 2-3 days and it would gradually harden and within two to three weaks it was done. Try to keep it in a dry warm place, under light bulbs or something similar works also.
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The problem I have seen from applying when it isn't warm enough is too much glue. It gets thick and extra sticks to the sinew, or you put extra on trying to make it work right. I never wrap mine. One of the best things about hide glue is that it has strength when it cools, you don't have to wait until it dries. I would advise what has already been said, apply it in a warm location.
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Sounds like you just didn't wait long enough if you were messing with it only an hour later? Like said before - the Knox will be like swelled up jelly at first until it starts loosing moisture. I don't wrap mine either but will not do anything with it for about two weeks.
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yea mate it takes like a day to dry visibly. then a bit longer till it sets some say 3 months.
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I'm not sure if I understood the problem completely, but you could prevent the sinew from lifting up on the back by tieing the bow into reflex after the glue has gelled. That way, pulling the sinew into compression, allowing it to shrink without having it lifting off of the back. - like on a horn/sinew composite.
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Thanks for the help, I think I see my way clear now.
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Qwill, I hope it goes better the second time. The sinew can be re used if you set it aside to dry. You will have to shred it all over again, but then it's pretty much like new. Ron
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All you need to do is soak the Sinew in Warm water and swish it around until the Knox Gelatin dissolves away....take the Sinew out and pull it apart and set it out flat to dry....and whenever you are ready to try again....it will be ready again....believe Me I have reused Sinew a time or two....once on a Bow that Broke....and once the first time I tried it and it turned out like Crap.... ;D
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I always reuse my sinew lay it in warm water and the glue will melt away.I always have the sinew smooth when I first put on the sinew but when it first start to get like rubber it wants to start peaking up and get those rough ridges most times it is to late by then to smooth it back down so if you want to wrap it down do it just as soon as it looses its stickyness with a ace bandage I have used electrical tape with the sticky side out and only leave it on overnight and it will be real smooth after you unwrap it it will still me rubbery and if you want you can put on a ace bandage to make sure it stays down. Some times I will put a weight in the handle area and set the tips on the seats of two chairs and let the weight hold it in a reverse bend for about a month I had a big attic so it was no problem just make sure its setting even if not adjust the limbs on the chair seats so booth limbs are taking the same bend or adjust the weight on the handle area.
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Okay if I chime in? I agree with everything that has been said, however What temp you heat your sinew at I think is very important,just as if you get sinew too hot it will turn up on you. My guess this is what happened along with possibly and some others,such as been said clean and I score the surface a little , And put a prime coat on first, I use a old arrow to smooth the material down, then one more light coat as soon as the tacky state is gone ,done too soon it will lift and gell and glob. Too much glue it will do also. And when you are done it is going to make some cracking noises at first, sometimes.So much for my two cents. Denny
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Whatever you do, don't get discouraged. It took me 5 tries to get sinew-backing right. And I still think I have room for improvement! ;D