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Quick question about sinew
WhistlingBadger:
So I've heard the "let it dry a week between layers" method, and I've heard the "get all the layers on then dry the whole thing out for a really long time" method. The latter one actually makes more sense to me, since subsequent layers are going to re-moisten the previous layers. Any thoughts on that? I've got a couple juniper kids' bows about ready to sinew and I'm pondering how to get it done.
superdav95:
WB. The sinew layers of 2 or 3 layers with allowing each layer to dry for 2 weeks will actually save drying time considerably. One big fat layer will take 6 months minimum or more depending on humidity and conditions and such. The last bow I did in layers only took me 2 months before it was dry enough to start bending it some. I ended up waiting 10 weeks in the end to get it covered, sealed up and finished. So in essence it saves time but not only this, it also helps in quality control of your layers of sinew as each one dries you can see any issues the come up whereas with one big thick layer you may not see buried issues or voids and lifts/delaminating. It’s comforting to see a good solid first layer as thin as it may be to solidly adhere well to your bow wood. It’s provides a great foundation for the next 2 layers if that makes sense. This is just my opinion and there may be some that will say one heavy layer is better. In my observation and experience with several sinew bows now is that is not the case. The issues I’ve had with sinew in my builds have been on the one big layer builds. Often I would see the top portion of the sinew exposed to the air would dry much quicker then the fibers underneath and cause air pockets and voids or lifts from the bow wood. Even wrapping it would not always fix this issue. I was able to salvage some but it was hit and miss. I’ve had much better success with the layers laid in 2 week intervals. Sinew is not cheap and it takes a lot of prep to get it ready to lay down too. I got tired of wasting sinew and having to salvage sinew from failed projects. Just my thoughts on this take it for what’s it’s worth.
stuckinthemud:
How do you know when sinew is dry?
WhistlingBadger:
Superdave, that makes sense. Thanks for the explanation.
Stuck, excellent next question.
superdav95:
--- Quote from: stuckinthemud on August 19, 2023, 01:13:40 pm ---How do you know when sinew is dry?
--- End quote ---
Yes it’s a very good question. I know this answer will likley not satisfy but I let it dry 2 weeks. That’s how I know it’s dry😃 In my climate that’s good and dry. You’ll notice an amber Color develop after the first week or so almost translucent. It will be hard and you should see wood underneath the first translucent layer. I guess you could try a moisture meter to be certain perhaps. I’ve never done this and find it unnecessary for this. One thing I’ve noticed as well and this is a little weird but it feels dry and not cool to the touch of that makes sense. When a damp or slightly damp item is drying it will feel cool to the touch. Try this out and you’ll feel it. It will be dry to the touch on the surface but still cool to the touch. Usually by week two it feels room temperature to the touch with my hand. This is my go to method now. Another way I’ve done before is by weight. I don’t use this method much anymore but it’s accurate. I’ll measure before and after sinew. This can be tricky as there are a lot of parts to include in your weight. This could in fact be your most definite way to know for sure. Ive done it before for my first few sinew bows and then stopped as I got a good sense after a while the time line of when it’s dry. If you weigh before and after sinew remember you have to account for the sinew dry weight then the dry weight of the glue and make note of that before mixing up your glue and soaking your bundles of sinew. If you use this method after a while you’ll get an idea when it dry. In my case by the middle of the second week I had gotten within a gram or two of complete water weight loss by drying. Now some variables come into it but it’s pretty close. This is a great way to learn actually for your first couple and gives you the confidence in knowing its dry and how long it takes. So long as you measure everything before in dry weight you should be fine. It’s a little more hassle but like I say it’s good information to have in the experience bank. Sinew may seem daunting but it’s worth it I think. Hope this helps. Cheers
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