Primitive Archer
Main Discussion Area => Bows => Topic started by: Blaflair2 on August 31, 2015, 08:10:51 pm
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What's y'all's method for knowing its dry? Anything besides the time it has been applied? I have this sinew backed yew bow living in my car seeing if the heat will get her to dry faster.
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a few weeks plus is a good idea(depending on humidity where you live), sinew is one of those things usually better not rushed, that being said,, I have started to tiller some bows after one week,, because I am not good at waiting either,, I think the down side of rushing,, is,,, it may not hold as much reflex as when cured properly,, and also the tiller will probably shift on you as the sinew does cure,, and the bow make pick up more weight than you expect,, just based on my experience with " bowyers impatience" ,, :)
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The sinewed bows I made I waited a month between courses, 2 or 3 courses of sinew. I check tiller and work to completion. After the tillering was done I'd add skins over the sinew and give it another few weeks. The skins hold the moisture in longer. I've heard of folks doing it all in a few weeks but if I'm going to put in the effort I can wait.
A lot depends on the R/H of where you live. The higher humidity the longer the wait.
I would store the bow between sessions over the hot water heater in the utility room where the temp and R/H are more constant.
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I've been keeping it in the car. And I don't know if the sinew all in one piece like I applied will dry faster? It seems dry. It hasn't moved reflex wise.
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I've always done sinew in layers so I don't know which is faster drying. Leave the windows opened a crack to let the moisture out of the car...or else you have a sauna. ;)
If you can try weighing it and when it quits loosing weight for a few days it is at equilibrium with the R/H. From there a dryer is necessary to reduce more moisture. Winter works well for me. ;)
You can probably shoot it long before I would without damaging it. Maybe someone else that is familiar with sinew backing will chime in.
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If you want it to dry quickly then you should put it on in multiple thin layers with two weeks or so drying time in between..
1mm of sinew takes about 2 weeks to dry. 2mm 4 weeks, 3mm 9 weeks, 4mm 16 weeks etc.
One thick layer will take much longer to properly dry as the wood also soaks up water from the glue.
One sure way to know when it's dry is to weigh the stave accurately then keep weighing it until the weight loss stops for a week.
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Mike is right on here. Double the thickness and it's gonna take 4x as long to dry at least.
I usually a it way longer than needed. Had one that looked and felt dry, must have been drying for a few months inside the air conditioning, had taken solid reflex, so I filled it out to 45#(didn't have a scale at the time). Came back to it like 6months later and it was up to 56#. Obviously it was not dry.
Now I just wait until it stops losing weight, and a few weeks extra for good measure and to mentally prepare for the next steps. Lol.
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The amount of glue you leave in the sinew plays a huge role.
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I have only sinewed two bows, the first bow I made and one a couple years ago. My first was so poorly made that it blew up after 30 shots in spite of the sinew. The sinew on my second pulled the wood apart when it dried. I knew it was substandard osage when I made the bow but didn't think it would matter with a sinew backing.
(http://img.photobucket.com/albums/v181/ekrewson/bow%20making/failure.jpg) (http://smg.photobucket.com/user/ekrewson/media/bow%20making/failure.jpg.html)
I have never put my moisture meter to a sinewed bow as it dried, has anyone checked the moisture this way?
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If you put the sinew on thick you can pack the bow in salt to pull the moisture out quickly. ;)
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That's interesting Pat, have you tried using salt?
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Of course.
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Eric - people forget that sinew contracts in all dimensions not just length. Although I do suspect that the wood hada flaw in it for that to happen.
Pearl - why do you think the amount of glue matters with reference to drying time?
Pat - I'd rather it dried slowly, look into how collagen bonds are formed.
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Its nearly all water.
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Pat - I'd rather it dried slowly, look into how collagen bonds are formed.
You still have to dry quickly enough to prevent decay of the matrix.
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i would say if you start to tiller the bow,, and the weight does not go up,, it is pretty dry,, you can always stop if you think it is not dry enough ,, and continue at a later time,, it is pretty forgiving,,, I do have a feeling,, that the best performance may come from properly cured sinew,, but have no proof of this,, the bows I started to early,, did gain weight,, but seemed to perform well despite the early start,, a wider design my have the same amount of of sinew as a narrow thick design, but dry quicker cause the sinew is not so thick,,there are lots of variables ,, and we are still re learning many things that have been long forgotten,,,I love sinew backed bows :)
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Leave it twice as long as you want to >:D >:D